Astronomy

http://www.universetoday.com/30537/w...llanic-clouds/

WHAT ARE MAGELLANIC CLOUDS?

Article Updated: 8 Nov , 2016
by Matt Williams
Since ancient times, human beings have been staring at the night sky and been amazed by the celestial objects looking back at them. Whereas these objects were once thought to be divine in nature, and later mistaken for comets or other astrological phenomena, ongoing observation and improvements in instrumentation have led to these objects being identified for what they are.

For example, there are the Small and Large Magellanic Clouds, two large clouds of stars and gas that can be seen with the naked eye in the southern hemisphere. Located at a distance of 200,000 and 160,000 light years from the Milky Way Galaxy (respectively), the true nature of these objects has only been understand for about a century. And yet, these objects still have some mysteries that have yet to be solved.

The sheer size of phenomena and the huge distances involved are hard to grasp...

http://www.universetoday.com/131879/...-5-times-mass/

Red dwarf stars have proven to be a treasure trove for exoplanet hunters in recent years. In addition to multiple exoplanets candidates being detected around stars like TRAPPIST-1, Gliese 581, Gliese 667C, and Kepler 296, there was also the ESO’s recent discovery of a planet orbiting within the habitable zone of our Sun’s closest neighbor – Proxima Centauri.

And it seems the trend is likely to continue, with the latest discovery comes from a team of European scientists. Using data from the ESO’s High Accuracy Radial velocity Planet Searcher (HARPS) and HARPS-N instruments, they detected an exoplanet candidate orbiting around GJ 536 – an M-class red dwarf star located about 32.7 light years (10.03 parsecs) from Earth.

According to their study, “A super-Earth Orbiting the Nearby M-dwarf GJ 536“, this planet is a super-Earth – a class of exoplanet that has between more than one, but less than 15, times the mass of Earth. In this case, the planet boasts a minimum of 5.36 ± 0.69 Earth masses, has an orbital period of 8.7076 ± 0.0025 days, and orbits its sun at a distance of 0.06661 AU.

I would only add to this that (a) circumstellar habitable zone is far too broad a category to be of use in identifying planets that can be lived on by humans. Note that one restriction would be that the atmosphere is similar to that on Earth.

2.7 light years away is a major technological restriction to Faster the Light (FTS) travel. It means it would take that many years travelling at the speed of light to get there. There is as yet no technology to make travel at the speed of light possible. Even less possible is the idea of a warp drive, such as we know from Star Trek.

We may be at the start of the space age, but we aren't going to the stars, not by a long chalk.

I suspect every star has planets of some sort circling it. We just don't know about them. I agree that we are not going to send people to those planets, but we could communicate with them with a message delay of 2.7 years. I also suspect that life will form where ever it is possible for life to exist.

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Originally Posted by YesNo

I suspect every star has planets of some sort circling it. We just don't know about them. I agree that we are not going to send people to those planets, but we could communicate with them with a message delay of 2.7 years. I also suspect that life will form where ever it is possible for life to exist.

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Assuming there are humans there that are about our level of technology. I doubt very much there are...

So far we haven't been able to find messages from anyone, but we have only started looking. We probably need to focus on those stars with exoplanets who could spot the Earth, if anyone there is looking, as one of their exoplanets. One of your previous posts mentioned doing something like this.

You can also use Lagrange Points to travel the solar system with minimum fuel requirements: http://www.universetoday.com/131953/...sport-network/. Only slightly slower but much more efficient.

"But it turns out there’s another way you can travel from planet to planet in the Solar System, using a fraction of the energy you would use with the traditional Hohmann transfer, and that’s using Lagrange points.

We did a whole article on Lagrange points, but here’s a quick refresher. The Lagrange points are places in the Solar System where the gravity between two objects balances out in five places. There are five Lagrange points relating to the Earth and the Sun, and there are five Lagrange points relating to the Earth and the Moon. And there are points between the Sun and Jupiter, etc.


Three of these points are unstable. Imagine a boulder at the top of a mountain. It doesn’t take much energy to keep it in place, but it’s easy to knock it out of balance so it comes rolling down.

Now, imagine the whole Solar System with all these Lagrange points for all the objects gravitationally interacting with each other. As planets go around the Sun, these Lagrange points get close to each other and even overlap.

And if you time things right, you can ride along in one gravitationally balanced point, and the roll down the gravity hill into the grasp of a different planet. Hang out there for a little bit and then jump orbits to another planet.

In fact, you can use this technique to traverse the entire Solar System, from Mercury to Pluto and beyond, relying only on the interacting gravity of all these worlds to provide you with the velocity you need to make the journey."

http://www.universetoday.com/131970/...ifreeze-ocean/

"The evidence keeps growing for a large subsurface ocean at Pluto, which also provides clues how the iconic ‘heart’ of Pluto was formed.

We reported in early October that thermal models of Pluto’s interior and tectonic evidence suggest an ocean may exist beneath Pluto’s heart-shaped Sputnik Planitia. Now, new research on data from the New Horizons mission shows more indications of an ocean just below Pluto’s surface that consists of a slushy, viscous liquid, kept warm from Pluto’s interior and a hint of anti-freeze.

“As far as we can tell, there’s no tidal heating helping to keep the ocean liquid,” Francis Nimmo from UC Santa Cruz told Universe Today. He is the first author of a paper on the new findings published today in Nature. “The main heat source keeping the ocean liquid is radioactive decay in Pluto’s rocky interior, although it certainly helps if there is an ‘antifreeze’ present.”

Nimmo said he suspects the ocean is mostly water with ammonia acting as an antifreeze. This subsurface ocean is also bulging, similar to the ‘mascons’ on the Moon, putting stress on Pluto’s icy outer shell, causing fractures consistent with features seen in the New Horizons images.

Another paper also published in Nature today from James Keane at the University of Arizona, also shows how a bulging subsurface ocean made Pluto’s heart ‘heavy,’ reorienting Pluto on its axis, so that Pluto’s heart is always pointing away from the moon Charon."

http://www.universetoday.com/107598/...e-kuiper-belt/

Future of the Kuiper Belt:
When he initially speculated about the existence of a belt of objects beyond Neptune, Kuiper indicated that such a belt probably did not exist anymore. Of course, subsequent discoveries have proven this to be wrong. But one thing that Kuiper was definitely right about was the idea that these Trans-Neptunian Objects won’t last forever. As Mike Brown explains:

We call it a belt, but it’s a very wide belt. It’s something like 45 degrees in extent across the sky – this big swath of material that’s just been churned and churned by Neptune. And these days, instead of making a bigger and bigger body, they’re just colliding and slowly grinding down into dust. If we come back in another hundred million years, there’ll be no Kuiper Belt left.
Given the potential for discovery, and what up-close examination could teach us about the early history of our Solar System, many scientists and astronomers look forward to the day when we can examine the Kuiper Belt in more detail. Here’s hoping that the New Horizons mission is just the beginning of future decades of research into this mysterious region!

We have many interesting articles here at Universe Today on the subject on the Outer Solar System and Trans-Neptunion Objects (TNOs).

And be sure to check out this article on the planet Eris, the latest dwarf planet and the largest TNO to be discovered.

And astronomers are expecting to discover two more large planets in our Solar System.

It is interesting that we can detect Kuiper belts around other stars. I wonder how that was done. We can barely detect exoplanets around those stars.

Using the Lagrange points seems like a nice way to move around the solar system for research purposes. The craft should get energy somewhere, perhaps from the Sun so that it could keep sending back data continually. If it is made small enough like those cubesats, research about the solar system could be very inexpensive.

There may be a problem with that, as space telescopes are likely to be located at Lagrange points: Spitzer is likely to be located at one. Traffic congestion? Or perhaps not, I have no idea how large Lagrange points are. They of course move about as they are based on the movement of the planets...

EarthSky often has quite useful information on all things, not just space. See http://earthsky.org/space/what-makes...round-the-moon

What makes a halo around the sun or moon? There’s an old weather saying: ring around the moon means rain soon. There’s truth to this saying, because high cirrus clouds often come before a storm. Notice in these photos that the sky looks fairly clear. After all, you can see the sun or moon. And yet halos are a sign of high thin cirrus clouds drifting 20,000 feet or more above our heads.

These clouds contain millions of tiny ice crystals. The halos you see are caused by both refraction, or splitting of light, and also by reflection, or glints of light from these ice crystals. The crystals have to be oriented and positioned just so with respect to your eye, in order for the halo to appear.

That’s why, like rainbows, halos around the sun – or moon – are personal. Everyone sees their own particular halo, made by their own particular ice crystals, which are different from the ice crystals making the halo of the person standing next to you.

Why is it called a 22-degree halo? Because the ring has a radius of approximately 22° around the sun or moon.

Come to think of it, clouds are mysterious. And they are not all alike which adds to the mystery.

http://dawn.jpl.nasa.gov/news/

The Dawn Mission has been exploring the dwarf planet Ceres for the lat 8 months. Now it will be going higher to get more views of it.

For more details on this study, see:
http://www.nasa.gov/feature/goddard/...s-cryo-volcano

This is the only known example of a cryovolcano that potentially formed from a salty mud mix, and that formed in the geologically recent past," Ruesch said.

For more details on this study, see:
http://www.nasa.gov/feature/goddard/...s-cryo-volcano

Ceres: Between a Rocky and Icy Place

While Ahuna Mons may have erupted liquid water in the past, Dawn has detected water in the present, as described in a study led by Jean-Philippe Combe of the Bear Fight Institute, Winthrop, Washington. Combe and colleagues used Dawn's visible and infrared mapping spectrometer (VIR) to detect probable water ice at Oxo Crater, a small, bright, sloped depression at mid-latitudes on Ceres.

Exposed water-ice is rare on Ceres, but the low density of Ceres, the impact-generated flows and the very existence of Ahuna Mons suggest that Ceres' crust does contain a significant component of water-ice. This is consistent with a study of Ceres' diverse geological features led by Harald Hiesinger of the Westfälische Wilhelms-Universität, Münster, Germany. The diversity of geological features on Ceres is further explored in a study led by Debra Buczkowski of the Johns Hopkins Applied Physics Laboratory, Laurel, Maryland.

Impact craters are clearly the most abundant geological feature on Ceres, and their different shapes help tell the intricate story of Ceres' past. Craters that are roughly polygonal -- that is, shapes bounded by straight lines -- hint that Ceres' crust is heavily fractured. In addition, several Cerean craters have patterns of visible fractures on their floors.

Some, like tiny Oxo, have terraces, while others, such as the large Urvara Crater (106 miles, 170 kilometers wide), have central peaks. There are craters with flow-like features, and craters that imprint on other craters, as well as chains of small craters. Bright areas are peppered across Ceres, with the most reflective ones in Occator Crater. Some crater shapes could indicate water-ice in the subsurface.

The dwarf planet's various crater forms are consistent with an outer shell for Ceres that is not purely ice or rock, but rather a mixture of both -- a conclusion reflected in other analyses. Scientists also calculated the ratio of various craters' depths to diameters, and found that some amount of crater relaxation must have occurred. Additionally, there are more craters in the northern hemisphere of Ceres than the south, where the large Urvara and Yalode craters are the dominant features.

"The uneven distribution of craters indicates that the crust is not uniform, and that Ceres has gone through a complex geological evolution," Hiesinger said.

Distribution of Surface Materials

What are the rocky materials in Ceres' crust? A study led by Eleonora Ammannito of the University of California, Los Angeles, finds that clay-forming minerals called phyllosilicates are all over Ceres. These phyllosilicates are rich in magnesium and also have some ammonium embedded in their crystalline structure. Their distribution throughout the dwarf planet's crust indicates Ceres' surface material has been altered by a global process involving water.

Although Ceres' phyllosilicates are uniform in their composition, there are marked differences in how abundant these materials are on the surface. For example, phyllosilicates are especially prevalent in the region around the smooth, "pancake"-like crater Kerwan (174 miles, 280 kilometers in diameter), and less so at Yalode Crater (162 miles, 260 kilometers in diameter), which has areas of both smooth and rugged terrain around it. Since Kerwan and Yalode are similar in size, this may mean that the composition of the material into which they impacted may be different. Craters Dantu and Haulani both formed recently in geologic time, but also seem to differ in composition.

"In comparing craters such as Dantu and Haulani, we find that their different material mixtures could extend beneath the surface for miles, or even tens of miles in the case of the larger Dantu," Ammannito said.

Looking Higher

Now in its extended mission, the Dawn spacecraft has delivered a wealth of images and other data from its current perch at 240 miles (385 kilometers) above Ceres' surface, which is closer to the dwarf planet than the International Space Station is to Earth. The spacecraft will be increasing its altitude at Ceres on Sept. 2, as scientists consider questions that can be examined from higher up.

Dawn's mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team."

It does look like a volcano, but why only one such volcano on Ceres? Have they found out what those bright spots are?

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Originally Posted by YesNo

It does look like a volcano, but why only one such volcano on Ceres? Have they found out what those bright spots are?

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Yes, they found out what the bright spots were ages ago. Need to go back and look them up.

There is a wikipedia website on this: https://en.wikipedia.org/wiki/Bright_spots_on_Ceres

Mostly salt, it seems.

The Dawn probe will now go into perpetual orbit round Ceres even after its lost all its capabilities.

Sometimes Earth/Sky comes up with some interesting posts. Here is one on Cassini, the probe of Saturn: http://earthsky.org/space/saturn-spa...-to-ring-graze.

Lots to learn and discuss here.

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Originally Posted by Dreamwoven

There is a wikipedia website on this: https://en.wikipedia.org/wiki/Bright_spots_on_Ceres

Mostly salt, it seems.

The Dawn probe will now go into perpetual orbit round Ceres even after its lost all its capabilities.

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I checked that site, but it seems that they don't really know. They mentioned: "...it is material with a high level of reflection, and suggested ice and salt as possibilities." It still appears to be speculation.

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Originally Posted by Dreamwoven

Sometimes Earth/Sky comes up with some interesting posts. Here is one on Cassini, the probe of Saturn: http://earthsky.org/space/saturn-spa...-to-ring-graze.

Lots to learn and discuss here.

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While it’s easy to feel nostalgic about the coming end of NASA’s wonderful Cassini mission to Saturn (source of so many incredible images), excitement is now building as the mission prepares to enter its grand finale year in 2017. NASA engineers have been pumping up the spacecraft’s orbit around Saturn this year to increase its tilt with respect to the planet’s equator and rings. On November 30, 2016, following a gravitational nudge from Saturn’s moon Titan, Cassini will go into an orbit that’ll send it just past the unexplored region at the outer edge of Saturn’s main rings. It’ll continue grazing the rings between November 30 and April 22, 2017, circling high over and under the poles of Saturn, diving past the rings every seven days, a total of 20 times. Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, California, said:

We’re calling this phase of the mission Cassini’s Ring-Grazing Orbits, because we’ll be skimming past the outer edge of the rings.

And that’s only the beginning of Cassini’s grand finale in 2017.

First, though, why is the mission ending? Cassini has been in space for nearly 20 years. It launched from Earth in 1997 and has been touring the Saturn system – weaving among the planet’s rings and moons – since 2004. Its discoveries include a global ocean within Enceladus and liquid methane seas on Titan, but even those amazing discoveries pale next to the dramatic consciousness shift space fans have experienced over the years of this mission. Prior to Cassini, we had only glimpsed Saturn and its rings and moons. Now we see them, in all their intricate and profound beauty.

But, now, the Cassini spacecraft is running low on fuel. And so the mission must end, but not before it run through a year-long lists of “firsts” at Saturn. That’s following a series of “lasts,” by the way, related to Saturn’s moons, in 2016.

Simply put, before its end, Cassini has more science to do. For example, on many of the upcoming passes through the ringplane, Cassini’s instruments will attempt to sample ring particles and molecules of faint gases close to the rings, directly. Linda Spilker said:

… we have two instruments that can sample particles and gases as we cross the ringplane, so in a sense Cassini is also ‘grazing’ on the rings.

During the first two orbits, the spacecraft will pass directly through an extremely faint ring produced by tiny meteors striking the two small moons Janus and Epimetheus. Ring crossings in March and April will send the spacecraft through the dusty outer reaches of the F ring. Earl Maize, Cassini project manager at JPL, said:

Even though we’re flying closer to the F ring than we ever have, we’ll still be more than 4,850 miles (7,800 km) distant. There’s very little concern over dust hazard at that range.

The concern about dust will increase, though, after April, as Cassini executes the later phases of its grand finale. Ultimately, Cassini will pass as close as 1,012 miles (1,628 km) above Saturn’s cloudtops as it dives repeatedly through the narrow gap between Saturn and its rings.

The mission’s planned end will come on September 15, 2017, when the spacecraft will plunge into Saturn’s dense atmosphere.

For now, though, NASA says, some preparatory work remains:

To begin with, Cassini is scheduled to perform a brief burn of its main engine during the first super-close approach to the rings on December 4. This maneuver is important for fine-tuning the orbit and setting the correct course to enable the remainder of the mission…

To further prepare, Cassini will observe Saturn’s atmosphere during the ring-grazing phase of the mission to more precisely determine how far it extends above the planet. Scientists have observed Saturn’s outermost atmosphere to expand and contract slightly with the seasons since Cassini’s arrival. Given this variability, the forthcoming data will be important for helping mission engineers determine how close they can safely fly the spacecraft.

Bottom line: The Cassini spacecraft has been shifting its orbit throughout 2016, preparing for the mission’s grand finale in 2017. On November 30, it’ll begin a series of 20 orbits that fly high above and below Saturn’s poles, plunging just past the outer edge of the main rings.

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Originally Posted by YesNo

I checked that site, but it seems that they don't really know. They mentioned: "...it is material with a high level of reflection, and suggested ice and salt as possibilities." It still appears to be speculation.

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In that case, everything in space research is just speculation. At some point we have to accept that. There just is no 100 percent confirmation of much space exploration.

Nevertheless, I shall continue to observe.

Thi is from nature.com:
The typically dark surface of the dwarf planet Ceres is punctuated by areas of much higher albedo, most prominently in the Occator crater1. These small bright areas have been tentatively interpreted as containing a large amount of hydrated magnesium sulfate1, in contrast to the average surface, which is a mixture of low-albedo materials and magnesium phyllosilicates, ammoniated phyllosilicates and carbonates2, 3, 4. Here we report high spatial and spectral resolution near-infrared observations of the bright areas in the Occator crater on Ceres. Spectra of these bright areas are consistent with a large amount of sodium carbonate, constituting the most concentrated known extraterrestrial occurrence of carbonate on kilometre-wide scales in the Solar System. The carbonates are mixed with a dark component and small amounts of phyllosilicates, as well as ammonium carbonate or ammonium chloride. Some of these compounds have also been detected in the plume of Saturn’s sixth-largest moon Enceladus5. The compounds are endogenous and we propose that they are the solid residue of crystallization of brines and entrained altered solids that reached the surface from below. The heat source may have been transient (triggered by impact heating). Alternatively, internal temperatures may be above the eutectic temperature of subsurface brines, in which case fluids may exist at depth on Ceres today.

This is how I am reading the paragraph from nature:

When they say that the surface is "punctuated by areas of much higher albedo", we all know that since we can see the spots. It is just a fancy way to say there are bright areas on the dwarf planet. However, we wouldn't know about those spots without that mission going there in the first place.

The spectra data showing sodium carbonate (https://en.wikipedia.org/wiki/Sodium_carbonate) is new information. There's a mysterious "dark component" and then apparently spectra evidence for phyllosilicates, ammonium carbonate or ammonium chloride. So they have found out something about those spots.

The theory of how it got to the surface of Ceres is unknown, however, they suspect it came from within Ceres. That would require a heat source to move it to the surface. That heat source could come from the energy of an impact or Ceres' own internal temperature.

I guess I wouldn't expect them to know much more than what they can get from electromagnetic waves since they didn't land on Ceres and do some drilling into the dwarf planet.

The Fermi Paradox tries to understand the absence of extra-terrestrial intelligent life in the universe. See also http://www.universetoday.com/39804/fermi-paradox/.

We live in a big Universe, billions of light years across. There are hundreds of billions of galaxies, and each one contains hundreds of billions of stars. Life happened here on Earth, and with countless other stars out there, you would think life would have arisen somewhere else. And yet, we have no evidence there’s any other life in the Universe. If life is common in the Universe, where are all the aliens. This is the Fermi paradox.

The Fermi Paradox was first described by the physicist Enrico Fermi. Even if we aren’t visited by aliens, we should see some evidence for them out in the Universe, or be able to detect their radio transmissions. And yet, scientists haven’t found a single piece of technology that wasn’t created by humans, or found a life form doesn’t share a common heritage with all life on Earth. There hasn’t been a single intelligent signal detected from the Universe.

There is a thirty-minute broadcast you can listen to here.

There are several intriguing possibilities, including the fear of being discovered by ET intelligent life that is too underdeveloped to understand that they can destroy a civilisation which is quite capable of implementing Mutually-Assured Destruction.

A final thought. It is quite likely that we remain a poorly developed civilisation merely because we have barely begun to explore the universe. Even our own solar system is incompletely explored (I am thinking here of Planet 9). The Kuiper Belt has been preliminarily explored by New horizons (Pluto and one other object not yet visited) and the Oort Cloud remains a vast unexplored area beyond the Belt. We of course also have telescopes located in space like WISE and Spitzer, Hubble, and James Webb Space Telescope.

There are a lot of ways communication with potential ET life this might happen. The links above should be read/listened to by anyone thinking of replying to this post, especially the 30 minute astronomycast link. Thank you.

http://www.universetoday.com/130230/...roid-belt-sun/

Its been very quiet, I've not found anything I thought worthwhile to add to my astronomy thread in the last 11 days.

Structure and Composition:
The Asteroid Belt consists of several large bodies, along with millions of smaller size. The larger bodies, such as Ceres, Vesta, Pallas, and Hygiea, account for half of the belt’s total mass, with almost one-third accounted for by Ceres alone. Beyond that, over 200 asteroids that are larger than 100 km in diameter, and 0.7–1.7 million asteroids with a diameter of 1 km or more.

It total, the Asteroid Belt’s mass is estimated to be 2.8×1021 to 3.2×1021 kilograms – which is equivalent to about 4% of the Moon’s mass. While most asteroids are composed of rock, a small portion of them contain metls such as iron and nickel. The remaining asteroids are made up of a mix of these, along with carbon-rich materials. Some of the more distant asteroids tend to contain more ices and volatiles, which includes water ice.
Despite the impressive number of objects contained within the belt, the Main Belt’s asteroids are also spread over a very large volume of space. As a result, the average distance between objects is roughly 965,600 km (600,000 miles), meaning that the Main Belt consists largely of empty space. In fact, due to the low density of materials within the Belt, the odds of a probe running into an asteroid are now estimated at less than one in a billion.

While many spacecraft have been to the Asteroid Belt, most were passing through on their way to the outer Solar System. Only in recent years, with the Dawn mission, that the Asteroid Belt has been a focal point of scientific research. In the coming decades, we may find ourselves sending spaceships there to mine asteroids, harvest minerals and ices for use here on Earth.

We’ve written many articles about the Asteroid Belt here at Universe Today. Here’s What is the Asteroid Belt?
In the 18th century, observations made of all the known planets (Mercury, Venus, Earth, Mars, Jupiter and Saturn) led astronomers to discern a pattern in their orbits. Eventually, this led to the Titius–Bode law, which predicted the amount of space between the planets. In accordance with this law, there appeared to be a discernible gap between the orbits of Mars and Jupiter, and investigation into it led to a major discovery.

In addition to several larger objects being observed, astronomers began to notice countless smaller bodies also orbiting between Mars and Jupiter. This led to the creation of the term “asteroid”, as well as “Asteroid Belt” once it became clear just how many there were. Since that time, the term has entered common usage and become a mainstay of our astronomical models.
How Long Does it Take to get to the Asteroid Belt?, How Far is the Asteroid Belt from Earth?, Why Isn’t the Asteroid Belt a Planet?, and Why the Asteroid Belt Doesn’t Threaten Spacecraft.

To learn more, check out NASA’s Lunar and Planetary Science Page on asteroids, and the Hubblesite’s News Releases about Asteroids.

Astronomy Cast also some interesting episodes about asteroids, like Episode 55: The Asteroid Belt and Episode 29: Asteroids Make Bad Neighbors.

I am surprised to hear that the entire asteroid belt contains only about 4% of the Moon's mass. However, I don't see why we would mine material on these asteroids. There is the cost of getting there and getting back.

I found this procedure of galaxi "feeding" interesting and it is related to the current theme of star composition:
http://www.astronomy.com/news/2016/1...-later-in-life

"Super-Galaxies Don’t Become Cannibals Until Later in Life
In their early years, the largest galaxies in the universe feed on recycled material from dead stars.
Before they turn to cannibalism, massive galaxies spend their infancy gobbling up recycled gas from earlier generations of star formation.

The Spiderweb Galaxy is actually more of a galaxy-in-progress. One day, it will be an enormous elliptical galaxy at the heart of a galactic cluster, but at the moment – technically, at a moment ten billion years away whose light is only just reaching us on Earth – it’s a group of about a dozen small proto-galaxies, slowly falling together and merging amid a vast halo of cold gas. At the center of that spiderweb of gas and merging galaxies sits a larger radio galaxy, which will one day form the core of the giant elliptical galaxy.

At 10 billion light-years away, the Spiderweb Galaxy offers astronomers a window into the formative years of the largest galaxies in the universe. It turns out that the birth of a super-galaxy is a more complex process than previously thought."

http://www.astronomy.com/news/2016/1...-later-in-life

I have noticed a lot of "feeding" metaphors used to describe what happens in galaxies. Before there was the idea of a black hole at the center of our galaxy which was supposed to eat some dust cloud a while back (it didn't happen) and now there are cannibals on an even larger frame.

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4


Here is the latest round-up of news from the Society for Popular
Astronomy.


"MARS ICE DEPOSIT HOLDS AS MUCH WATER AS LAKE SUPERIOR
NASA/Jet Propulsion Laboratory

Researchers using the Mars Reconnaissance Orbiter have discovered
that, frozen beneath a region of cracked and pitted plains on Mars,
lies about as much water as is contained in Lake Superior, largest of
the North-American Great Lakes. Scientists examined part of Mars'
Utopia Planitia region, in the mid-northern latitudes, with the
orbiter's ground-penetrating Shallow Radar (SHARAD) instrument.
Utopia Planitia is a basin with a diameter of about 3,300 km,
resulting from a major impact early in Mars' history and subsequently
filled. Analyses of the radar data from more than 600 overhead passes
reveal an ice deposit more extensive in area than the British Isles.
The deposit ranges in thickness from about 80 to 170 metres, with a
composition that is 50 to 85% water ice, mixed with dust or larger
rocky particles. At the latitude of the deposit -- about 45 degrees
-- ice cannot persist on the surface of Mars today; it sublimes into
water vapour in the thin, dry atmosphere. The Utopia deposit is
shielded from the atmosphere by a covering of soil, estimated to be
about 1 to 10 metres thick. Mars today, with an axial tilt of 25
degrees, accumulates large amounts of water ice at the poles. In
cycles lasting about 120,000 years, the tilt varies to nearly twice
that much, warming the poles and driving ice to middle latitudes.
Climate modelling and previous findings of buried mid-latitude ice
indicate that frozen water accumulates away from the poles during the
long high-tilt periods.

The newly surveyed ice deposit spans latitudes from 39 to 49 degrees
within the plains. It represents less than 1% of all known water
ice on Mars, but it more than doubles the volume of thick, buried
ice sheets known in the northern plains. Ice deposits close to the
surface are being considered as a resource for potential astronauts.
The deposit described here is probably more accessible than most water
ice on Mars, because it is at a relatively low latitude and it lies in
a flat, smooth area where landing a spacecraft would be less hazardous
than in some of the other areas where there is buried ice. The
Utopian water is all frozen now. If there were a melted layer --
which would be significant for the possibility of life on Mars -- it
would have been evident in the radar scans. However, some melting can
not be ruled out during different climate conditions when the planet's
axis was more tilted."

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4

NEW FAMILY OF STARS IN CORE OF MILKY WAY
Liverpool John Moores University

Astronomers have discovered a new family of stars in the core of our
Milky Way galaxy, providing new insights into the early stages of the
Galaxy's formation. The discovery, made from the Sloan Digital Sky
Survey, has shed new light on the origins of globular clusters. One
of the projects of this collaboration is APOGEE (the Apache Point
Observatory Galactic Evolution Experiment), which collects infrared
data for hundreds of thousands of stars in the Milky Way. It was
through observing stars in the infrared towards the Galactic Centre
that the discovery was made of a new population of stars, the like
of which had been seen before only inside globular clusters. That
intriguing new family of stars could possibly have belonged to
globular clusters that were destroyed during the violent initial
formation of the Galactic centre, in which case there would have been
about 10 times more globular clusters in the Milky Way in its early
stages than there are today. That could mean that a substantial
fraction of the old stars inhabiting the inner parts of the Galaxy
today may have been formed initially in globular clusters that were
later destroyed.

The finding helps astronomers address fascinating questions such as
what is the nature of the stars in the inner regions of the Milky Way,
how globular clusters formed, and what role they played in the
formation of the early Milky Way -- and by extension the formation of
other galaxies. The centre of the Milky Way is poorly understood,
because it is blocked from view by intervening dust. Observing in the
infrared, which is less absorbed by dust than visible light, APOGEE
can see the centre of the Galaxy better than other methods. From the
observations the chemical compositions of thousands of stars could be
determined; among them was a considerable number of stars that
differed from the bulk of those in the inner regions of the Galaxy,
owing to their very high abundance of nitrogen. While not certain, it
is suspected that those stars resulted from the destruction of
globular clusters. They could also be the by-products of the first
episodes of star formation taking place at the beginning of the
Galaxy's history.

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4



NEW FAMILY OF STARS IN CORE OF MILKY WAY
Liverpool John Moores University

Astronomers have discovered a new family of stars in the core of our
Milky Way galaxy, providing new insights into the early stages of the
Galaxy's formation. The discovery, made from the Sloan Digital Sky
Survey, has shed new light on the origins of globular clusters. One
of the projects of this collaboration is APOGEE (the Apache Point
Observatory Galactic Evolution Experiment), which collects infrared
data for hundreds of thousands of stars in the Milky Way. It was
through observing stars in the infrared towards the Galactic Centre
that the discovery was made of a new population of stars, the like
of which had been seen before only inside globular clusters. That
intriguing new family of stars could possibly have belonged to
globular clusters that were destroyed during the violent initial
formation of the Galactic centre, in which case there would have been
about 10 times more globular clusters in the Milky Way in its early
stages than there are today. That could mean that a substantial
fraction of the old stars inhabiting the inner parts of the Galaxy
today may have been formed initially in globular clusters that were
later destroyed.

The finding helps astronomers address fascinating questions such as
what is the nature of the stars in the inner regions of the Milky Way,
how globular clusters formed, and what role they played in the
formation of the early Milky Way -- and by extension the formation of
other galaxies. The centre of the Milky Way is poorly understood,
because it is blocked from view by intervening dust. Observing in the
infrared, which is less absorbed by dust than visible light, APOGEE
can see the centre of the Galaxy better than other methods. From the
observations the chemical compositions of thousands of stars could be
determined; among them was a considerable number of stars that
differed from the bulk of those in the inner regions of the Galaxy,
owing to their very high abundance of nitrogen. While not certain, it
is suspected that those stars resulted from the destruction of
globular clusters. They could also be the by-products of the first
episodes of star formation taking place at the beginning of the
Galaxy's history.

If they found more stars at the center of the galaxy that would suggest to me that they have identified new sources of mass. This would reduce the need for dark matter or a black hole at the center of our galaxy.

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4

EXTREMELY FAINT SATELLITE GALAXY OF MILKY WAY
National Astronomical Observatory of Japan

Astronomers have found an extremely faint dwarf satellite galaxy of
the Milky Way. The satellite lies in the direction of the constellation
Virgo and has accordingly been named Virgo I. At an absolute
magnitude of -0.8 in the optical waveband, it may well be the faintest
satellite galaxy yet found. Its discovery suggests the presence of a
large number of yet-undetected dwarf satellites in the halo of the
Milky Way, and provides important insights into galaxy formation
through hierarchical assembly of dark matter. Currently, some 50
satellite galaxies of the Milky Way have been identified. About 40
of them are faint and diffuse and belong to the category of 'dwarf
spheroidal galaxies'. Many recently discovered dwarf galaxies,
especially those found in systematic photometric surveys such as the
Sloan Digital Sky Survey (SDSS) and the Dark Energy Survey (DES), are
very faint, with absolute luminosities in the optical waveband less
than -8 magnitude. They are called 'ultra-faint dwarf galaxies'.
However, previous searches made use of telescopes of apertures 2.5 to
4 metres, so only satellites relatively close to the Sun or those with
brighter magnitudes were identified.

The combination of the large aperture of the 8.2-m Subaru Telescope
and the large field of view of the Hyper Suprime Cam (HSC) instrument
is very powerful for this study. It enables an efficient search to
be made for very faint dwarf satellites over large areas of the sky.
The first step in searching for a new dwarf galaxy is to identify an
over-density of stars in the sky, using photometric data. Next is to
assess that the over-dense appearance is not due to line-of-sight or
accidental juxtapositions of unrelated dense fields, but is really a
stellar system. The standard method for doing that is to look for a
characteristic distribution of stars in the colour-magnitude diagram
(analogous to the Hertzsprung-Russell diagram). Stars in a general
field show no particular patterns in this diagram. The team examined
the early data of the Subaru Strategic Survey with HSC and found an
apparent over-density of stars in Virgo with very high statistical
significance, showing a characteristic pattern of an ancient stellar
system in the colour-magnitude diagram. It is indeed a galaxy,
because it is spatially extended with a radius of 124 light-years --
larger than a globular cluster with comparable luminosity. The
faintest dwarf satellites identified so far are Segue I, discovered by
SDSS (-1.5 mag) and Cetus II in DES (0.0 mag). Cetus II is yet to be
confirmed, as it is too compact as a galaxy, so Virgo I may turn out
to be the faintest one so far discovered. It lies at a distance of
280,000 light-years from the Sun, and such a remote galaxy with such a
low luminosity has not been identified in previous surveys. It is
beyond the reach of SDSS, which has previously surveyed the same area
in the direction of the constellation Virgo.

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4

DO EXTREMELY REDDENED QUASARS EXTINGUISH STAR FORMATION?
University of California - Riverside

Galaxies formed and grew thousands of millions of years ago by
accumulating gas from their surroundings, or colliding and merging
with other young galaxies. Those early stages of galaxy assembly are
believed to be accompanied by episodes of rapid star formation, known
as starbursts, and rapid growth of a single super-massive black hole
in each galactic centre. A popular paradigm for such evolution has
the black holes growing mostly in obscurity, buried deep within the
dusty gas in the centres of the galaxies. Those are rich star-forming
galaxies, until a blowout of gas and dust (outflow) extinguishes the
star formation and halts further growth in the black holes. At that
stage there is revealed the luminous material in the immediate
vicinity of the rapidly growing black hole in the galactic nucleus.
Such objects are known as quasars. Quasars can eject material at
high speeds, possibly helping to drive the blowout and regulate star
formation in their host galaxies. However, many aspects of that
evolutionary scheme are not understood. Quasars that are partially
obscured by dust, which reddens their light in a way that is similar
to the apparent reddening of the Sun as it approaches sunset on
Earth, might provide windows into galactic evolution during the brief
transition stage when the starburst is winding down and the visibly
luminous quasar is first being revealed in the galactic centre. New
research describes the discovery of the new population of extremely
red quasars detected in the Baryon Oscillation Sky Survey (BOSS) of
the Sloan Digital Sky Survey (SDSS).

The main goal of that study was to determine the size of the
population of extremely red quasars, and to characterize its basic
properties in comparison with the much larger population of quasars
in the BOSS--SDSS survey overall. The extremely red quasars were
selected for study because of their extreme colour, but the analysis
reveal a number of peculiar properties consistent with a unique and
possibly young evolutionary stage. In particular, they have an
exceptionally high incidence of powerful quasar-driven outflows that
could be involved in galaxy-wide blowouts of gas and dust. Overall,
the gaseous environments around the black holes appear to be more
extended and more energetic than the environments of normal quasars,
which might occur at specific times when young gas-rich host galaxies
are dumping prodigious amounts of matter into the central black holes,
creating an extreme variety of quasars. More work is needed now to
examine the population of extremely red quasars further and understand
its relationship to the general phenomenon of quasars and, perhaps, to
a particularly violent phase of quasar-galaxy evolution.

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4

LARGE NUMBER OF DWARF GALAXES FOUND IN EARLY UNIVERSE
University of California at Riverside

A team of researchers has found a large population of distant dwarf
galaxies that could reveal important details about a productive period
of star formation in the Universe thousands of millions of years ago.
The findings build on a growing body of knowledge about dwarf
galaxies, the smallest and dimmest galaxies in the Universe. Though
relatively diminutive, they are very important for understanding the
history of the Universe. It is believed that dwarf galaxies played a
significant role during the 're-ionization era', in transforming the
early Universe from being dark, neutral and opaque to one that is
bright, ionized and transparent. Despite their importance, distant
dwarf galaxies remain elusive, because they are extremely faint and
mostly beyond the reach of even the best telescopes, so the current
picture of the early Universe is incomplete. However, gravitational
lensing, which was predicted by Einstein from his general theory of
relativity long before it was actually observed, causes a massive
object such as a galaxy located along the line of sight to another
distant object to act as a natural lens, concentrating the light
coming from the background source. The phenomenon sometimes allows
us to discover distant dwarf galaxies that would otherwise be too
faint to detect.

As a proof of concept, in 2014 the team targeted one cluster of
galaxies that produces the gravitational-lensing effect and got a
glimpse of what appeared to be a large population of distant dwarf
galaxies. The team used the Wide-Field Camera 3 on the Hubble Space
Telescope to take deep images of three clusters of galaxies. They
found the large population of distant dwarf galaxies from a time when
the Universe was between two and six thousand million years old.
That cosmic time is critical, as it was the most productive time
for star formation in the Universe. In addition, the team obtained
spectroscopic data from the Multi-Object Spectrograph for Infrared
Exploration (MOSFIRE) on the Keck telescope, and confirmed that the
galaxies belonged to that important cosmic period. Those dwarf
galaxies are 10 to 100 times fainter than galaxies that had been
previously observed from that period of time. Though faint, the
galaxies are far more numerous than their brighter counterparts.

The study demonstrates that the number of dwarf galaxies changed
during that important time period in such a way that they were
even more abundant at earlier times. In fact, the researchers had
unveiled a population of dwarf galaxies that were the most numerous
galaxies in the Universe during those times. Despite their individual
faintness, the dwarf galaxies produced more than half of all ultra-
violet light during that era. As ultraviolet radiation is produced
by young hot stars, dwarf galaxies evidently hosted a significant
fraction of newly-formed stars at that period of cosmic time. Those
results suggest that dwarf galaxies played a prominent role in the
re-ionization era; they will be among the primary targets of the next
generation of telescopes, particularly the James Webb Space Telescope,
scheduled to be launched in 2018.

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4


MARS PROBE RETURNS FIRST PICTURES
BBC Online

Europe's and Russia's new satellite at Mars has sent back its first
images of the planet. The Trace Gas Orbiter (TGO) arrived on October
19, putting itself into a highly eccentric elliptical parking orbit,
which must be circularized over the coming year before the mission
can become fully operational. Scientists have, however, taken the
opportunity of some close passes to the planet in recent days to check
out the TGO's instrumentation. They are delighted at the quality of
the pictures returned from the camera system, CaSSIS (the Colour and
Stereo Surface Imaging System). Two of TGO's sensors - NOMAD and ACS
- also came through their early tests. Those are the sensors that
will make a detailed inventory of Mars' atmospheric gases. In
particular, they will go after the components that constitute less
than 1% of the planet's air -- chemical species such as methane, water
vapour, nitrogen dioxide, and sulphur dioxide. Methane is the main
focus. From previous measurements, its concentration seems to be low
and sporadic in nature, but the mere fact that it is detected at all
is really fascinating.

Methane (CH4) is the simplest organic molecule, and ought to be
destroyed easily in the harsh Martian environment, so its persistence
-- and the occasional spikes in its signal -- indicate a source that
replenishes the gas. The speculation is that it could be coming from
microbial life somewhere on the planet. It will be CaSSIS's job to
look for possible topographical forms on the surface that might tie
into methane sources. A fourth instrument, FREND, will sense hydrogen
in the near-surface. Those data can be used as proxy for the presence
of water or hydrated minerals. That again is information that could
yield answers to the methane question. TGO was the unspoken success
on the day that ESA's Schiaparelli lander crashed onto Mars. The
surface probe had been dropped off by TGO and was making its ill-fated
descent just as the satellite took up its parking orbit, and the
successful insertion went almost unnoticed in the fuss over
Schiaparelli. TGO is the first phase in a joint venture at Mars that
Europe is undertaking with Russia. The second step in the project,
known as ExoMars, is to put a robot rover on the planet in 2021. It
needs a lot of money from the European side to go forward, however --
just over 400m Euros. Research ministers from ESA member states are
meeting this week in Switzerland to try to resolve the budget problem.

It is interesting that a probe can do more than get evidence from the electromagnetic spectrum, but can actually collect samples from the atmosphere. I wonder why the rover on the planet is not doing that already.

I had thought they would have detected evidence for microbial life on Mars by now.

Sorry for the long delay in my reply!

I doubt whether a rover on the surface could undertake atmospheric measurements, you clearly need a satellite for that. This is just the first phase. As stated in their wiki post: https://en.wikipedia.org/wiki/ExoMars the second step will need to be done, to put a robot rover on the planet in 2021:

TGO is the first phase in a joint venture at Mars that
Europe is undertaking with Russia. The second step in the project,
known as ExoMars, is to put a robot rover on the planet in 2021. It
needs a lot of money from the European side to go forward, however --
just over 400m Euros. Research ministers from ESA member states are
meeting this week in Switzerland to try to resolve the budget problem.

After this they need to do phase 2 Exomars (Europe and Russia combined) in 2012, if it is approved.

It must be difficult co-ordinating all this. Especially as Russia has not done this before (no space projects since the USSR). See the wikipedia post on this: https://en.wikipedia.org/wiki/ExoMars. NASA has done all the Mars exploration up till now using land-based rovers.

I think we need to spend some time to catch up on this. Its been 3 months since your reply, YesNo.

It is good to see someone besides NASA doing this research. There should be permanent robotic bases on Mars and the Moon if for no other reason than to test and improve the technology.

Today I got my first issue of the Swedish equivelent of Popular Astronomy: Populär Astronomi. I will be interested to compare it with the British version. It only comes out quarterly, though, not bi-monthly.

Today I was in Bollnäs Library and reading the journals. Popular Astronomy had an article on the space photometry revolution in which Hubble played a pioneering part. Now, new generations of space telescopes are becoming more and more prominent. The Spitzer infra-red space telescope is just one of a whole range of space telescopes deploying or under development.

This will radically improve our ability to study so-called goldylocks planets around other stars. There is an article on this in the current issue of The Swedish magazine Popular Science (Populär Vetenskap) has one on the search for life in other worlds. Some 3,000 worlds have been found that are classed as Goldylocks Worlds, possible harbouring life in some form or another.

Much of this - for now all of it - is speculation, but it will be interesting to see whether any life (e.g. micro-organisms) will be found on other exo-planets going around "near-by" stars.

It looks like we still haven't found a Goldilocks planet yet, but "transit spectroscopy" sounds promising if a Goldilocks planet is ever discovered especially nearby.