Astronomy

[Dreamwoven]

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.

[YesNo]

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.

[Dreamwoven]

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.

[free]

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.

[YesNo]

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.

[Dreamwoven]

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.

[YesNo]

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.

[YesNo]

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?

[mal4mac]

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?

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.

[YesNo]

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?

[Dreamwoven]

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...

[YesNo]

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

[Dreamwoven]

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.

[YesNo]

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.

[Dreamwoven]

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.