Astronomy

From a Popular Astronomy email update:
METEORITE MAY REPRESENT BULK OF MARS' CRUST

Brown University

NWA 7034, a meteorite found a few years ago in the Moroccan desert, is like no other rock ever found on Earth. It has been shown to be a 4.4-billion-year-old piece of the crust of Mars and, according to a new analysis, rocks just like it may cover vast swaths of Mars. In a new paper, scientists report that spectroscopic measurements of the meteorite are a spot-on match with measurements from orbit of the Martian dark plains, areas where the planet's coating of red dust is thin and the rocks beneath are exposed. The findings suggest that the meteorite is representative of the 'bulk background' of rocks on the Martian surface. When scientists started analyzing the meteorite in 2011, they knew that they had something special. Its chemical make-up confirmed that it came from Mars, but it was unlike any other Martian meteorite. Previously, all the Martian rocks found on Earth were classified as SNC meteorites (shergottites, nakhlites, or chassignites). They are mainly igneous rocks made of cooled volcanic material, but the new object is a breccia, a mash-up of different rock types welded together in a basaltic matrix. It contains sedimentary components that match the chemical make-up of rocks analyzed by the Mars rovers. Scientists concluded that it is a piece of Martian crust -- the first such sample to be found on the Earth.

I realize I didn't know what a breccia was, but now it makes sense. I don't see why this particular type of black beauty does not occur on Earth.

Since it is Chinese New Year, I thought I'd try to figure out what that meant. It seems that it is first based on the winter solstice, a solar phenomenon. The second new moon after that is Chinese New Year with the celebration lasting three days.

In the process of looking that up, I found http://live.slooh.com/ which supposedly offers astronomical events for view. I'll try to make it for the new crescent moon event tomorrow.

Europa, one of the moons of Jupiter (the one with surface seas) may be explored for signs of life: http://www.space.com/28614-nasa-euro...l?cmpid=559074.

The Europa Clipper is one of the projects under consideration, a probe that sails around Euro in its atmosphere taking measurements.

Interesting observation about there being no threads (but this one) on astronomy. Is mainstream literature anti-astronomy? Here's some quotes to back up my thesis:

Tennyson:

"Storm, and what dreams, ye holy Gods, what dreams!
For thrice I waken'd after dreams. Perchance
We do but recollect the dreams that come
Just ere the waking. Terrible: for it seem'd
A void was made in Nature, all her bonds
Crack'd; and I saw the flaring atom-streams
And torrents of her myriad universe,
Ruining along the illimitable inane,
Fly on to clash together again, and make
Another and another frame of things
For ever. "

Whitman:

WHEN I heard the learn’d astronomer;
When the proofs, the figures, were ranged in columns before me;
When I was shown the charts and the diagrams, to add, divide, and measure them;
When I, sitting, heard the astronomer, where he lectured with much applause in the lecture-room,
How soon, unaccountable, I became tired and sick; 5
Till rising and gliding out, I wander’d off by myself,
In the mystical moist night-air, and from time to time,
Look’d up in perfect silence at the stars.

William Blake was critical of reductive scientific thought. In his famous picture "Newton", the straight lines and sharp angles of Newton’s profile suggest that he cannot see beyond the rules of his compass.

http://www.tate.org.uk/art/artworks/blake-newton-n05058

Behind him, the colourful, textured rock may be seen to represent the creative world, to which he is blind.

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Originally Posted by free

I looked through a telescope only once. I saw Saturn with its ring. It was a beautiful feeling.

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I was obsessed with astronomy, for a period, as a kid, and young adult. Seeing Saturn's rings was certainly a highlight, along with seeing Jupiter's moons and some of the Messier objects. This seems like a Whitmanesque response, "In the mystical moist night-air ... Look’d up in perfect silence at the stars." But I found, on getting heavily into it, it becamet rather tedious, "When the proofs, the figures, were ranged in columns before me; When I was shown the charts and the diagrams, to add, divide, and measure them;..., I became tired and sick".

Whitman makes astronomy, here, sound like filling in tax return. Astronomy is strange! Part poetry and part accountancy.

Note Tennyson's "illimitable inane". He has a point - I mean what's up there really? Not Gods or even humans, just a bunch of inane rocks. But then again, these rocks are playing in a vastness beyond comprehension, within endless time; which leads to incomprehension, awe, and terror. Maybe issues too big and difficult for literature to comprehend and cope with? On one side, the most extreme inanity, on the other, the highest sublimity. Strange subject!

I agree with you, it is a strange subject, very technical yet very dramatic. Of course, this website is about literature so I couldn't expect a lot of interest in astronomy. Thats why this is only one thread out of hundreds or even thousands of threads.

I too saw the moons of Jupiter through a friend's telescope and only became interested in astronomy today where the internet covers it pretty well. Your quoting of Tennyson and Whitman shows that poetry is written inspired by the night sky.

YesNo, thanks for yet another link! Ive added it to my astro bookmark. There are now several people dropping by with posts: Gilliat Gurgle, NikolaiI, 108 Fountains, Calidore, so it is a topic of wide interest.

We are also now in a fascinating era for space exploration.

That there might be life under the ice of Europa sounds intriguing. It is so far from the sun.

I tried to see the moons of Jupiter with my binoculars two nights ago and was not able to. Another part of the problem may be with the way I am focusing the binoculars. One part surely is that I am not using a tripod.

Regarding literature, science fiction has some interest in astronomy. What I have discovered is that prior to this thread I didn't realize that I didn't know anything about astronomy or even astrology. It is only recently that I understood what Jupiter's retrograde motion even meant. Then looking at the sky, even I can see Jupiter with all the light pollution getting in the way. I can see why this planet stood out in the past.

As you say, Jupiter is very easily seen now, but by the time it get warm enough for me to go out and look with my binoculars it may be too light for viewing.

I've started to visit the New Horizons website almost daily. It is still 1 Au to Pluto (that's about the distance of Earth to the Sun) but the probe is flying extremely fast. There are now images of two of the small moons of Pluto, Nix and Hydra. There were found by Hubble space telescope recently.

I follow this thread with great interest, but, unfortunately, I have not enough knowledge about astronomy to post any comment. Maybe it would be interesting to remind that Newton's laws of motion written in 'Principia', in 17th century, are basical for today's cosmic exploration.

I forgot about New Horizons. It looks like Pluto has at least five moon and Charon is tidally locked with Pluto meaning both Charon and Pluto show each other the same side like the moon shows us its same side.

If you have a smart phone, free, you can download one of the sky apps. They are just maps, but one can watch the relative positions of the planets change through them and then know where to look when the sky is transparent enough to view them. Although I am interested in the current discoveries, I am even more interested in how we got to where we are in our understanding and the different views people had in the past including astrological views. We should be able to use Newton's laws and astronomical data that he would have had available to be able to predict where a planet will be. I still don't know how to connect those dots.

I don't have a smart phone.

I discovered a new kind of cloud: lenticular clouds, they look odd and spaceship like. You can read about it on EarthSky. One of the comments is by a pilot and he said in a comment that they can be dangerous to fly into, because they cause a lot of turbulence. The last picture is particularly dramatic catching the red setting (or rising?) sun!

Clouds could be a subject of its own to view and take pictures of, the way sunlight catches them, etc. Tornadoes and even minor whirlwinds are also interesting.

I know you don't have a smart phone. I'm still trying to figure out how to use mine although I've had it long enough. Because the map changes daily I am able to see Jupiter move to the west (retrograde). One of the things I noticed using it is that the sun is still in Aquarius but astrologically we are supposed to be in Pisces. I realize this is due to the Precession of the Equinoxes, but I didn't really understand (and probably still don't) what that meant until just recently. With so much stuff spinning around it is hard to know which direction is prograde and which is retrograde or "precessing". I expect the sky to move from east to west because my limited experience only sees the diurnal motion, but planets move from west to east across the sky.

One of the things I am trying to make sense out of, which I know is not of great astronomical importance, are these lyrics by James Rado and Jerome Ragni from the Hair musical: http://en.wikipedia.org/wiki/Aquariu...he_Sunshine_In

When the moon is in the Seventh House
And Jupiter aligns with Mars

I understand the alignment part. The planets are in conjunction. But what is this moon being in the seventh house?

The lenticular clouds do look like ufos although what they remind me of are the clouds on Jupiter that seem to flow in lines across the planet. I don't know how clouds can do something like that on Jupiter nor how clouds can move like those lenticular examples on earth.

I think I'm beginning to understand what a "house" is. Correct me if I'm wrong.

The precession of the equinoxes has been known for over 2000 years. http://en.wikipedia.org/wiki/Axial_precession What it means is that when the equinox occurs the sun will actually be in a slightly different position with respect to the stars than it was last year. It looks as if the stars are moving westward (retrograde, precession) with respect to the vernal equinox. If one goes beyond the obvious diurnal motion, one expects the stars to move eastward.

Around 500 BC, the sun was in Aries. Today it will be on the beginning edge of Aquarius. So that is why people talk about the "age of Aquarius" because at the time of the equinox the sun will be this year around Aquarius however one defines its boundaries, but not Aries any more. Each year beginning with the vernal equinox is divided into twelve units of 30 degrees each. These are the "houses" and they correspond to constellations starting with Aries and ending with Pisces. However, these are not the constellations that the sun is actually going through at the time, but just a name for a different division of the sky referencing back to the order of these constellations in the zodiac.

What I wonder is how did Hipparchus discover this? What tools did he use to see that there was a difference at the vernal equinox?

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Originally Posted by YesNo

What I wonder is how did Hipparchus discover this? What tools did he use to see that there was a difference at the vernal equinox?

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Read on:

http://en.wikipedia.org/wiki/Axial_p...ion#Hipparchus

"According to Ptolemy's Almagest, Hipparchus measured the longitude of Spica and other bright stars. Comparing his measurements with data from his predecessors, Timocharis (320–260 BC) and Aristillus (~280 BC), he concluded that Spica had moved 2° relative to the autumnal equinox."

For tools check out:

http://en.wikipedia.org/wiki/Astrolabe#Ancient_world

http://en.wikipedia.org/wiki/Dioptra

Precession is an interesting phenomenon, another example is the precession of the perihelion of Mercury. The measurements of this were found to disagree with the predictions of Newtonian theory. Einstein's general theory of relativity explained them, and this was perhaps the first significant proof of this theory.

Yes, I missed the comparison between Hipparchus' measurements and those over 100 years prior to his measurements. I may try making an astrolabe out of paper: http://www.joh.cam.ac.uk/library/lib...strolabe/build

I looked at the moon through my binoculars thinking of what Galileo's arguments might have been. Everyone knew the moon was not a uniform color, but they didn't think there were mountains on the moon which Galileo tried to show by pointing to the shadows. If I step back and pretend that I don't know there are craters on the moon and just looked would I actually see the evidence for a non-uniform surface?

I've always understood "Houses" to refer to astrology rather than astronomy. Having said that, the ancients especially in India and China, were working with houses at the time when the distinction between astronomy and astrology was not made. Not sure about that, though...

I'm trying to figure out how the Indian astrology differs. I think they used the the stars more than the Sun during the Spring equinox as a starting point. The "house" is just a 30 degree region of the sky from a starting point. There are also "decans" or 10 degree regions of the sky putting three of these in each house.

With Galileo, I understood he found it difficult even getting those on his side to see what he saw through his telescope and I am beginning to see the difficulty by looking through the binoculars. I think I can see the evidence for the non-uniform lunar surface and the Milky Way being composed of stars, but I am having a hard time seeing the moons of Jupiter. One would have to see them clearly enough to notice that they change position around Jupiter.

It also seems obvious that Venus and Mercury should be circling the Sun because they switch from morning to evening stars and do not stray too far from the Sun. This was clear to Martianus Capella in the fifth century, but went against Ptolemy's authority: http://en.wikipedia.org/wiki/Martianus_Capella

I know very little about astrology, I'm afraid. Once I tried to cast a horoscope, but I didn't trust my judgements!

The first big event is very soon, when the Dawn mission approaches the dwarf planet of Ceres on 6th March.

I was amused by the fact that there is a rather vicious debate over Pluto's status and a clique of pluto-haters. Funny how even in astronomy you still get the most emotional debates.

It looks like we will learn more about Ceres and Pluto this year. That they have not cleared their environments seems to be the major reason they are not considered "planets". Those bright spots on Ceres have caught my interest.

I found Nick Lomb's "Transit of Venus" in the library. There are rare events when Venus crosses in front of the sun. They would be evidence that Venus is circling the Sun along with the phases of the planet. The first time this was seen was in 1631 and I guess the prediction of when it occurred is due to Kepler. Prior to sending radio signals to get the distance from Earth to Venus, the transit was supposed to be a way to determine what that distance was and then using Kepler's laws determine the distance form the Earth to the Sun to use as a basis for measuring other distances.

The definition of the IAU is odd. Too detailed and with too many ifs and buts. Has Earth cleared its orbit? Depends how you define it. See this post on a new astro website I found yesterday.

If Earth completely cleared its neighborhood there wouldn't be any fear of an asteroid hitting earth. I didn't know there were five dwarf planets: Ceres, Eris, Pluto, Makemake, and Haumea. I hadn't even heard of the other three. Why isn't Pluto's largest moon Charon included in the list of dwarf planets? They are tidally bound and similar in size that they could be said to be orbiting each other as they orbit the sun. The idea of a lost planet or two way out there that we haven't found is also interesting.

I believe Pluto's large moon is classed as well a moon. Your comment highlights the ludicrous nature of the definition of a planet. Pluto-Charon is a new phenomena as far as I know. We have seen it before in suns that are locked together in other galaxies, and sometimes planets going round one of the double stars is thrown over to going round the other. I saw a post on this in Astronomy Now a year or two ago. If that is not having an "uncleared orbit" I don't know what is! IAS is still very bound to a solar-centric view of the universe. There may even be more dwarf planets in orbit around Pluto.

I also agree that the possibility of a large planet going around the sun is intriguing. Pluto takes 3-and-a-half centuries to make one circuit the sun. How long would an even more remote planet/dwarf planet take?

We should know what those whit spots are on Ceres are within the next few days when Dawn goes into orbit around Ceres.

The Dawn Probe has ion propulsion, so it can use it as a brake to slow it down such that it can be gently captured into Ceres orbit. Then it will stay in orbit for a period to examine Ceres more closely.

That electric, ion propulsion is interesting. From the link you provided it can make a space craft go ten times faster than chemical propulsion using energy from the sun. I wonder why xenon is used and not some other element? Also I wonder if there is a way to harvest elements in space or around atmospheres of planets to replenish the xenon?

Xenon is an inert gas, like Helium and Neon, but heavier. Maybe it's used because it will not react with any of the materials in the spaceship, (e.g., it will not explode like hydrogen and oxygen!) Because it's heavier you can store a greater mass in your fuel container. Anyway, I'm jut guessing - get googling or ask on physics forum.

I did find that the fuel has to be easy to ionize and have a high mass/ionization ratio (that doesn't make sense to me) along with the contamination issue. Any material could be used as a propellant.

http://en.wikipedia.org/wiki/Ion_thruster#Propellants

I plan to observe Leo constellation. It is most visible from the late March, through April and May. This constellation seems interesting to me. :)

Back in the 1980s, at least, liquid metals were being considered as sources of ions for thrusters. I'm not sure what the situation is today. You would get gallium, or some other metal, to flow along a tungsten needle and generate ions coming off at the point using an electromagnetic field that would then keep the metal-gas ions in line and get them moving at speed. One would think it would be easier to mine metals than extract Xenon from (say) Jupiter's atmosphere, and they would (surely) be easier to store. Check out "liquid metal ion sources" of you want to read up on this.

Based on the Google Sky Map, both the moon and Jupiter are near Leo. I have only identified Algieba and Regulus in Leo while watching Jupiter. I should be able to see Denebola if the sky is clear enough.

Xenon is supposedly hard to get, but it is apparently easy to ionize. From the article argon is more common. I like the idea of getting energy from the sun and atoms from the atmosphere of the planets one visits for these space probes.

Last night I saw Orion constellation. It is easily recognized by its three bright stars close to each other called 'Orion's belt'.

I don't really know either how ion propulsion works, so join the club…
:)
Dawn is getting really close to Ceres, now some 35,000 miles, and retro- ion propulsion is slowing down a bit more. It should enter orbit around Ceres in a couple of days (March 6). I understand that it will be orbiting Ceres but starting on its dark side so we will not get any pictures or other images, until Dawn re-emerges on the other side into the sunlight. The following website is the one to watch for future info: http://dawn.jpl.nasa.gov/mission/status.asp. The two white spots that are so intriguing are seen on the image at the above link and there is a third image on the far left near the edge of the screen. There may even be others.

Ion propulsion works slowly, takes weeks to build up in space, so is useless for launching to escape velocity, but perfect for the delicate operation of going into orbit around Ceres.

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Originally Posted by free

Last night I saw Orion constellation. It is easily recognized by its three bright stars close to each other called 'Orion's belt'.

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Alnitak, Alniram, and Mintaka - I used to memorise such things when I was 12 :) Just below the belt is the famous Orion Nebula. It's a "fuzziness" that can be seen by the very sharp eyed, and should be obvious in binoculars. It's a vast cloud of gas from which stars are forming as you look - the closest region of massive star formation to Earth.

Might be a good place to send our ion powered robotic self-reproducing spacecraft on their first journey to the stars. Lots of material floating around for them to use!

Orion is a fascinating constellation - it also has two of the top ten brightest stars in the sky. One is Betelgeuse a red supergiant, on the top left shoulder. The other is Rigel at bottom right leg - a blue-white supergiant.

I agree about Orion constellation, it is very easy to identify by the three stars in a line and the two stars you identify: Betelgeuse and Rigel. Orion is the hunter and its easy to see the Hunter with her bow.

The link for the Dawn mission called Vesta a "giant asteroid". With Ceres being a "dwarf planet", there must be something that distinguishes these two names. Why is one a dwarf planet and the other a giant asteroid?

I think that a dwarf planet is round, planet-shaped, while an asteroid of any size is not.

It isn't very round, but Vesta apparently went through differentiation where the interior heated up and heavy elements sank while lighter elements rose to the surface.

In this video, there is a suggestion that it should be classified as the smallest "terrestrial planet". I also found it interesting that Jupiter's gravity stopped the rest of the asteroids from joining together. It "stirred them up" somehow. http://www.space.com/13902-vesta-ast...rf-planet.html

I'm afraid I have really no idea. I didn't even know Jupiter was not part of the solar system until what? something happened. But you can obviously choose yourself how to define vesta, a terrestrial planet or a large asteroid.

I don't either. But I had never thought of Ceres being a planet before. Or Vesta. Maybe the criteria of having an interior that heated up at one point would quality. However, then the Moon would be a planet.

Although I have not seen the retrograde movement of Jupiter outside, I was able to note the change on the app. I am looking forward to trying to make out Leo outside. The moon is quite bright now and past Leo.

I agree, except that the moon - perhaps Luna is a better name - is a moon, that is it is captive in the orbit of another planet, Earth.

It was full moon yesterday, I saw it near Jupiter a couple of days before. I am not well up on constellations, Orion and the Plough are the only two I can identify with any confidence.

The first constellation I could identify was Big dipper. My father showed it to me when I was a child. It is best visible in Apil.

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Originally Posted by YesNo

I don't either. But I had never thought of Ceres being a planet before....

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Ceres isn't a planet, it's an asteroid. Don't listen to those who call it a micro-planet, or whatever, you'll just encourage them. Probably the same people who say Pluto isn't a planet. They are trying to destroy my childhood certainties, and historical precedent, and that's not nice. Don't rock my world by unnecessary reclassification of rocks :)