Astronomy

The Journal Popular Astronomy has auroras as one of its special topics. I looked it up on 20 December when there was a lot of aurora activity on our latitude of 61 north. That morning at 5 am there had been a false dawn on the horizon due north of our house, a strip of clear sky, so it could have been that we saw. Dawn here in midwinter is around 9 am. There was probably colourful aurora activity, which was seen over all of Britain, even in the far south. But aurora are transitory phenomena so demand patience to watch and identify them. I can't do that as it means staying up for long hours, sacrificing sleep. This NASA page is also about auroras.

This link from your NASA link shows an aurora from space: http://www.nasa.gov/content/goddard/...uses-an-aurora

They called this "space weather" and a "geomagnetic storm". I wonder why there are always in northern latitudes? Perhaps they are in southern latitudes as well.

There are aurora at both poles - aurora australis is the other one.

Happy astronomical new year!

Thank you prendelemick! Happy astronomical year to you too.

This morning at 8 am it was still dark but the sun was soon going to rise. Before it did I was looking eastward out of the window at the sky lightening and for the first time I noticed the noctiluscent clouds, presaging the dawn. They were very beautiful, and I spent several minutes admiring them. Tonight had been the shortest day of the year, so it was especially welcome.

Happy Winter Solstice. Here is some information about what people do around Stonehenge during this time that I found by accident: http://www.telegraph.co.uk/news/scie...tice-2015.html

I didn't realize there were things like noctiluscent clouds. From the pictures I can see how they might confuse them with regular clouds early in the morning or late in the evening.

Yes, they are, of course, ordinary regular clouds, but very high in the sky (at 85 to 76 km high) and so very cold, forming ice crystals, which reflect direct sunlight. They were only discovered (or publicly noticed) in 1885.

At first I didn't "notice" these clouds as being noctilucent, they were just pretty. But when I thought about it further and looked up noctilucent clouds it confirmed to me that this is what they are. The sun shines on them from below the horizon so it takes a specific combination of circumstances to see them. And then to classify them as a distinct phenomena. Now I know, I will keep an eye out for them in future.

The Kuiper Belt is where many of the minor planets (like Ceres, Pluto, Makemake, and Haumea and some of the Moons like Neptune's Triton and Saturn's Phoebe) are thought to have originated. Ceres is the most recent planet thought to have originated here.

We clearly know relatively little about the Kuiper belt and KBOs (Kuiper Belt Objects). See this extract from the Wikipedia item on it:

The Kuiper belt /ˈkaɪpər/ or /'køypǝr/[1] (as in Dutch), sometimes called the Edgeworth–Kuiper belt, is a circumstellar disc in the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun.[2] It is similar to the asteroid belt, but it is far larger—20 times as wide and 20 to 200 times as massive.[3][4] Like the asteroid belt, it consists mainly of small bodies, or remnants from the Solar System's formation. Although many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia and water. The Kuiper belt is home to three officially recognized dwarf planets: Pluto, Haumea, and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, are also thought to have originated in the region.[5][6]

See the posts of 12 16 2015 on this, earlier in this thread.

The Wikipedia article on KBOs continues and shows by its language how little we know of the Kuiper Belt:

The Kuiper belt was named after Dutch-American astronomer Gerard Kuiper, though he did not actually predict its existence. In 1992, 1992 QB1 was discovered, the first Kuiper belt object (KBO) since Pluto.[7] Since its discovery, the number of known KBOs has increased to over a thousand, and more than 100,000 KBOs over 100 km (62 mi) in diameter are thought to exist.[8] The Kuiper belt was initially thought to be the main repository for periodic comets, those with orbits lasting less than 200 years. However, studies since the mid-1990s have shown that the belt is dynamically stable, and that comets' true place of origin is the scattered disc, a dynamically active zone created by the outward motion of Neptune 4.5 billion years ago;[9] scattered disc objects such as Eris have extremely eccentric orbits that take them as far as 100 AU from the Sun.[nb 1]

I might as well continue with the references to the last and most distant area of solar influence, the Oort Cloud. The language degenerates further as the Oort Cloud is described in hypothetical language, like "thought to be..." and "thought to comprise..." and "astronomers conjecture that...". The Oort Cloud is thought to define the outer limits of the gravitational dominance of the sun, and the origins of a whole class of comets (like Halley's) that pass close to Earth at intervals.

This is a quote from the item:

The Oort cloud is thought to comprise two regions: a disc-shaped inner Oort cloud (or Hills cloud) and a spherical outer Oort cloud. Objects in the Oort cloud are largely composed of ices, such as water, ammonia, and methane.

Astronomers conjecture that the matter composing the Oort cloud formed closer to the Sun and was scattered far into space by the gravitational effects of the giant planets early in the Solar System's evolution.[3] Although no confirmed direct observations of the Oort cloud have been made, it may be the source of all long-period and Halley-type comets entering the inner Solar System, and many of the centaurs and Jupiter-family comets as well.[6]

It is striking how little we know of this area of space within the sun's sphere of influence!

We don't know as much as I thought we did either, but I am glad they hesitate to say something definitely. They could have said, "The Oort cloud comprises two regions." I would have been more gullible and believed them. I am probably still too gullible.

One thing I didn't realize until reading the various links in this thread is that objects can be pushed away from the Sun by the gravitational effects of larger planets. I previously imagined that everything was doing its best to avoid falling into the Sun or one of the planets.

The Oort Cloud has continued to fascinate me. It is so far way that even Voyager 1 (which is the furthest out of the Voyager probes) will not reach it for another 300 years:

Space probes have yet to reach the area of the Oort cloud. Voyager 1, the fastest[53] and farthest[54][55] of the interplanetary space probes currently exiting the Solar System, will reach the Oort cloud in about 300 years[4][56] and would take about 30,000 years to pass through it.[57][58] However, around 2025, Voyager 1's radioisotope thermoelectric generators will no longer supply enough power to operate any of its scientific instruments, preventing any meaningful exploration by Voyager 1. The other four probes currently escaping the Solar System either are already or are predicted to be non-functional when they reach the Oort cloud, however it may be possible to find an object from the cloud that has been knocked into the inner solar system.

One proposal for exploration is to use a craft powered by a solar sail that would take around 30 years to reach its destination.[59] In the 1980s there was a concept for probe to reach 1000 AU in 50 years called TAU, among its missions would be to look for the Oort cloud.[60]

Other probes are in preparation, notably the Whipple Mission, and the Whipple Discovery Mission.

I didn't realize the Oort Cloud was that far away. The solar sail technology looks promising.

Looking at the morning sky, I see that Jupiter and Venus are getting further and further apart in the sky. Supposedly Saturn is above the horizon but I haven't seen it yet.

Mercury is also above the horizon at this time, after sunset. An opportunity to see it. Planet shine with a steady light, they don't twinkle like stars. See http://earthsky.org/tonight/mercury-...y-after-sunset

The headline at the 7.30 pm SVT news last night was that we may get to see the Northern Lights all over Sweden. I doubt we will from our home at least, just a glimpse at 5 am on the northern horizon. See this Space.com item.

Based on the link it is interesting that these sunspot cluster eruptions affect us in two ways. First there is the "flare", which I assume comes at the speed of light and causes an "ionization event" which may cause radio blackouts. The second is the "coronal mass ejection" which takes time to reach us and appears as the northern lights a few days later.

I have been able to see Saturn in the morning sky, but not yet Mercury in the evening sky because of clouds.

I am gradually learning about the aurora (borealis and australis). We never see the full glory of curtains of shimmering blue, shifting and changing, not at our latitudes. You have to be inside the polar circle when the conditions are right. At 61 degrees north we see the light in the northern sky but no more. the australis must be even harder to see, as there is no continental land even at 60 degrees south, apart from Antarctica. There is an old Aberdeen song about the northern lights.

Here's a YouTube link to that song: https://www.youtube.com/watch?v=-SNODgG0Fd4

While watching the Sun rise this morning it occurred to me that the planets and finally the Moon are the last that can be seen in the sky as it brightens. The stars have long disappeared. The planets reflect the Sun and are nearer to us than the stars and it seems to make sense that they should remain visible longer than the stars. When I turned my back to the Sun I could see the entire landscape slowing increase its ability to reflect the Sun. Sharp shadows began to appear. I know all that is obvious. I just didn't quite realize it before.

The u-tube link has shots in it that make it clear that the northern lights (as shifting blue curtains) can be seen from Aberdeen, at 58 degrees north. So they can be seen in Southern Norrland at 61 degrees north, you just have to catch it at the right time, presumably staying up all night in clear weather. That was very useful to know.

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 413 2016 January 3


GIANT COMETS COULD ENDANGER EARTH

RAS

A team of astronomers reports that the discovery of hundreds of giant comets in the outer regions of the Solar System over the last two decades implies that those objects pose a much greater hazard to life than asteroids. The giant comets, termed centaurs, have unstable orbits crossing the paths of the massive outer planets Jupiter, Saturn, Uranus and Neptune. The planetary gravitational fields can occasionally deflect the objects towards the Earth. Centaurs are typically 50 to 100 kilometres across, or larger, and a single such body has more mass than the entire population of Earth-crossing asteroids found to date. Calculations of the rate at which centaurs enter the inner Solar System indicate that one will be deflected onto a path crossing the Earth's orbit about once every 40,000 to 100,000 years. Whilst in near-Earth space, they are expected to disintegrate into dust and larger fragments, flooding the inner Solar System with cometary debris and making impacts on our planet inevitable.

Known severe upsets of the terrestrial environment and interruptions in the progress of ancient civilizations, together with our growing knowledge of interplanetary matter in near-Earth space, indicate the arrival of a centaur around 30,000 years ago. That giant comet would have strewn the inner planetary system with debris ranging in size from dust all the way up to lumps several kilometres across. Specific episodes of environmental upheaval around 10,800 BCE and 2,300 BCE, identified by geologists and palaeontologists, are also consistent with the new understanding of cometary populations. Some of the greatest mass extinctions in the distant past, for example the death of the dinosaurs 65 million years ago, may similarly be explained on the giant-comet hypothesis. In the last three decades scientists have invested a lot of effort in tracking and analysing the risk of a collision between the Earth and an asteroid. But we need to look beyond our immediate neighbourhood too, and look out beyond the orbit of Jupiter to find centaurs. Those distant comets could be a serious hazard. The researchers have also uncovered evidence from disparate fields of science in support of their model. For example, the ages of the sub-millimetre craters identified in lunar rocks returned in the Apollo programme are almost all younger than 30,000 years, indicating a vast enhancement in the amount of dust in the inner Solar System since then.

This from earth/sky: http://earthsky.org/earth/four-new-e...periodic-table

I thought they found all the elements already. It looks like there is no end to the number of these provided we can build the technology necessary to fuse them. I like how the article called them "superheavies".

I've been watching the morning sky more recently along with the sunrise. Nothing unusual to report except that it is all amazing.

Beth Moon has a collection of photographs of stars and old trees: http://www.bethmoon.com/DiamondNights.html

In her artist's statement she mentioned two experimental results from the University of Edinburgh and Lawrence Edwards correlating changes in plants and changes in our solar system and galaxy.

Some astronomers in our South Island got a much longer session than they expected at Mt St John Observatory: http://www.stuff.co.nz/the-press/757...le-force-winds

The AstroCafe with glass roofs is a great idea. Can see part of the Milky Way from it.

An enclosure with glass roofs is all I really need.

And minimal light pollution, which the sit also has. Seems to have clear skies, too.

I am also new to this forum and hope it will be useful for me.

Welcome to the forum and the astronomy thread. Would you like to tell its a bit about yourself and your interest in astronomy?

Welcome, swathisharan! One of the things I've found useful about this thread is I started looking at the planets and the Moon. I even know some constellations now.

How sofia flight revealed Pluto secrets.

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Originally Posted by The Atheist

Nebulae and planets, mostly. The prettiest bits, which is all any shop-bought amateur scope is good for. The moon is really cool through a good 'scope as well.

I'm inheriting $350,000,000 from Nigeria in a couple of weeks' time and I've decided I'm going to buy the Mt John observatory! One of the darkest places on the planet which is easily accessible.

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I've been checking some of the details on this Observatory. Here are some links:

Canterbury on NZ South Island seems to be a good location for a major observatory. Mt. John Observatory has its own wikipedia page, and here is more info on it (including a fine 360 degree view from it.).

Loopy String theory ? a possibility: https://www.quantamagazine.org/20160...antum-gravity/ ... or not.

Quote:

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But a number of factors may be pushing the camps closer together. New theoretical findings have revealed potential similarities between LQG and string theory. A young generation of string theorists has begun to look outside string theory for methods and tools that might be useful in the quest to understand how to create a “theory of everything.” And a still-raw paradox involving black holes and information loss has given everyone a fresh dose of humility.

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Quote:

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Herman Verlinde, a theoretical physicist at Princeton University who frequently works on string theory, finds it plausible that methods from LQG can help illuminate the gravity side of the duality. In a recent paper, Verlinde looked at AdS/CFT in a simplified model with only two dimensions of space and one of time, or “2+1” as physicists say. He found that the AdS space can be described by a network like those used in LQG. Even though the construction presently only works in 2+1, it offers a new way to think about gravity. Verlinde hopes to generalize the model to higher dimensions. “Loop quantum gravity has been seen too narrowly. My approach is to be inclusive. It’s much more intellectually forward-looking,” he said.

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I tried to watch the video which I think depicts the "2+1" model ( flatland ! ) expanding to a higher order of dimensionality, but my bandwidth cap gaks it (I'll be able to watch during a 2am - 8am pst stint later Monday morning {good grief it's only 23 seconds long !!!})

I haven't the math nor knowledge to fully grasp either theory, but I still find it fascinating that we may be able to better understand black holes and gravity, and the universe in general, better some day.

Ta ! (short for tarradiddle),
tailor STATELY

This is very interesting, I have looked up Quanta Magazine and the Simons Foundation, and your post combines the interest in Astronomy and parts of another thread on this forum that I also subscribe to, on Cosmology whose two main contributors are desiresjab and YesNo.

I wasn't aware of Quanta Magazine, nor of the Simons Foundation before reading your post, but will keep myself better informed on this in future: thanks!

Today's Dagens Nyheter has an article on black holes in association with the award of the Crafoord Prize for 2016 on Mathematics and Astronomy (this is in English). The prize is awarded to those who develop research that is not covered by the Nobel Prize).

One of the things I found interesting in the reference Tailor STATELY cited was another article claiming that supersymmetry had been falsified: https://www.quantamagazine.org/20121...eek-new-ideas/ This makes me wonder if string theory itself makes any sense, but I don't know enough about it.

I don't know whether there are black holes or not or what metaphysical difference it would make but I am beginning to doubt they exist, not just because theoretically "information" can't be lost in the black hole, whatever that information happens to be, but because we did not see the black hole that supposedly exists at the center of our galaxy "eat" a cloud last year as predicted. If we can't get predictions right at such close range, how can we trust data coming from other galaxies that black holes exist?

The whole thing about information is puzzling. On the one hand it implies that reality may have no substance in the usual sense, which I think is the case. One the other it implies information is still a form of unconsciousness, a reality that can be swallowed up in a black hole, which is something I doubt.

I admit that I'm a philosophical idealist which implies that I don't believe in the existence of unconscious matter. The position is the opposite of a philosophical materialist. So I have a bias that could be falsified if some unconscious matter could be found, but is information or waves of potentiality forms of unconsciousness? These metaphors are moving in the right direction, as I understand the word "right", but they still seem faulty to me.

I have to admit I missed that article in Quanta Magazine. It does, as you say, raise issues concerning the whole matter.

Solid evidence for a 9th planet: http://earthsky.org/space/solid-evid...ch-astronomers

10 times more massive than the Earth. It is amazing what we might have missed. I wonder if it's discovery would eliminate the need for dark matter in our solar system?

Today space.com has an item on the next space telescope, WFIRST, due operational 2014. It may be this will do what you are looking for?

Quote:

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Originally Posted by YesNo

10 times more massive than the Earth. It is amazing what we might have missed. I wonder if it's discovery would eliminate the need for dark matter in our solar system?

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No, even a planet 10X larger than Earth would be a midget against Jupiter and its gravitational impact would be negligible, which is why it's been hiding for so long.

The planets we do know about are putting on a stunning display at the moment, with Saturn, Jupiter, Mars & Venus in line with the rising sun. We've been waiting for a clear morning and were up at 4 to have a look.

Saturn in particular was sensational, with the moons gleaming like they'd been polished.

Best of all was as we were showing the 6 year old the Southern Cross, a meteor flitted past.

Yes, the mornings can be very nice. I was up early this morning but it was overcast.