Ask MetaFilter questions tagged with astronomy

Where can I go stargazing in the Boston area?

Plutor — Mon, 09 Nov 2009 09:03:09 -0800

Where can I go stargazing in the Boston area? I want to take my wife to see the Leonids next week. Where can we go in the area that's as dark as possible but is convenient, comfortable, and legal?

Please help me find when the moon disappears, so I can watch it.

Kickstart70 — Fri, 23 Oct 2009 22:27:55 -0800

Back about a decade ago, I happened to be watching in early evening as the moon went from thin sliver to complete disappearance. It was one of those unexpected and somewhat wondrous moments of my life (due to many circumstances of the time, and the unplanned coolness of it). I'd like to see it again. Is there some schedule for me to tell when this is going to happen again visible from my area? 53N,-122.36W, if that helps.

Is there a perfect orbit?

doublehappy — Fri, 16 Oct 2009 16:56:05 -0800

Is there a distance at which a satellite will orbit a body indefinitely? Is this distance a universal constant? As I understand it, satellite bodies are generally getting closer or further away from the body they orbit. Our moon, for example, is getting further away.

This morning I was reading a great essay by Amy Leachin the Best American Essays 2009.

In the second paragraph, it is noted that unless you [a satellite] happen to roll onto a track precisely 18,254 miles above your planet, the law ejects you or dashes you down. One moon in our solar system has achieved synchronous orbit, being pledged forever to its planet--Pluto's moon Charon. The other 168 moons have not.

According to google, 18,154 miles = 29,216 kilometers.

The wikipedia article about Charon cites a distance of 17,536 ± 4 km to system barycenter, 19,571 ± 4 km to the center of Pluto
. The radius of Pluto is, apparently, 1,153 ± 10 km. 19,571-1,153=18,418, which is close to 18,254 (though not 'precisely'), but nowhere near 29,216.

Am I missing something obvious (I'm not very good at space, so I am pretty sure this must be the case) or is Leach using poetic license, or is it a bit of both?

I find it hard to believe that there would be a universal perfect orbit distance, as celestial bodies are of varying mass, and there are also external tidal forces acting on them. However, I also find it hard to believe that there are big balls of rock and ice in mutual orbit, and that these systems are, themselves, in orbit around a huge ball of gas.

Uh...hang on, just give me a minute.

Demogorgon — Mon, 12 Oct 2009 10:34:31 -0800

What is the most important scientific question of our time? I volunteer at an observatory for a local amateur astronomers' society and one of the guests at a recent star party came up and asked, "What do you think is the most important question science has to answer right now?" Obviously, there is no right or wrong answer, but after the party was over a lot of us were still talking about this question and I ended up learning a great deal from my fellow club members that I might otherwise not have.
The next time this question gets asked I want to be prepared to offer a variety of answers from differing fields and opinions. I don't expect to represent every answer as an expert, but I'd like to be able to give a few more examples than I was able to, and then correlate them to some book recommendations from the answers in this thread about introductions to your field.
I also think it is important to frame the question in a way that can be meaningfully answered, i.e. "What is the most important scientific discovery about to be made?" or something like that.
Of course, I had my own answer in mind, but as a relative layperson to that branch of study I had a really hard time articulating why it was so important to "science." Therefore, if you are uniquely affiliated with a specific field that you think will produce a game-changer, feel free to get as technical as you're comfortable doing.

Thanks!

I want to be a scientist in my spare time!

adverb — Tue, 06 Oct 2009 07:32:01 -0800

How can I be use my spare time to advance a scientific cause? I always thought I'd be a scientist when I grew up, but it hasn't worked out that way. I'm happy with what I'm doing now, but something still gnaws at me to get involved with something scientific - astronomy and other physical sciences, mostly.

I'm looking for something that I can do to help a scientific cause or project - something more involved than SETI@Home, but is not too demanding on what little leisure time I have. Any ideas?

Online Astronomy course?

OlderThanTOS — Mon, 14 Sep 2009 10:07:51 -0800

Can someone recommend an online introductory college-level Astronomy course? I am training to be a high school biology teacher. My state (Minnesota) requires me to have a slightly broader education than I do. The gap is Astronomy. Best would be an Astronomy/Earth Science course.

I need to have an introductory Astronomy class before I take the Praxis II exam. The class needs to be online as I am already committed with student teaching and my practicum work.

Has anyone had great (or terrible) experiences? Cheaper gets extra bonus points!

Four of the clock it was, so I as I guesse

zvs — Wed, 05 Aug 2009 12:57:54 -0800

How can I estimate the time that a photo was taken? I'm working on a rephotography project (the link is my profile website, if you want an idea of what I'm dealing with). I've gotten the hang of many of the common problems I encounter when duplicating photos, but one thing still gets me -- time of day. I try to estimate based on the angle of a shadow, but that usually only gets me within a three hour window, and I hate sitting around waiting for the sun to move.

I'm a good enough geometer that I can usually figure out what the angle of a shadow is relative to true north using Photoshop, a street map, and a protractor. I have the date each photo was taken. I know NYC is about 15 minutes off of true noon for the time zone, and I know the angle varies seasonally. How can I do the math?

into a black hole

mwhybark — Tue, 04 Aug 2009 11:17:14 -0800

Any Cloudy Nights folks on MeFi? I am googling around in getting going with backyard astronomy and Cloudy Nights appears to be (or to have been) a decent resource, but it has been nothing but failed MySQL connections and php pathing errors since I started digging. Any info? Is it dead, Bones? I did find this older AskMe which includes a bunch of good info, btw.

http://ask.metafilter.com/13386/quality-astronomytelscope-websites

It's a podcast about something!

Dreamcast — Wed, 22 Jul 2009 23:57:03 -0800

What are some educational (yet interesting) podcasts? I'm looking for some "educational" podcasts. Specifically, I'm interested in subjects like history, astronomy (preferably geared more towards laymen), mythology, and just random trivia in general.

I'm interested in hearing any favorites you might have.

Previously, of course, but that's a couple of years old.

Was the entire universe created by the Big Bang, or is the space/time generated by the Big Bang part of a larger universe?

Lownotes — Tue, 23 Jun 2009 10:55:20 -0800

Was the entire universe created by the Big Bang, or is the space/time generated by the Big Bang part of a larger universe? I was astounded recently to discover that the known universe has been measured from end to end, and it is 165 billion light years wide.

So, if you look at it that way, all of space/time is now a big egg-like ovoid of matter and energy.

If all the matter and energy generated by the Big Bang is now a gigantic ovoid:

1. Where is the Milky Way located in that ovoid?

2. If we are closer to one end than the other, do the photos we have of the most distant reaches of the known universe depict the far end or the near end?

3. Is this giant egg the entire universe, or is there space/time beyond the ovoid in which other Big Bangs could have occurred.

4. If there are other ovoids, will we ever be able to detect them?

How much detail could the Hubble telescope see?

crazyray — Tue, 12 May 2009 20:35:38 -0800

What resolution would the Hubble Telescope be able to discern, if we pointed it at my back yard instead of into the stars? Would it be able to pick up individual blades of grass? Would it be able to see bacteria or anything not visible to the naked eye? Could it see the illuminated dial of my watch at night? For the sake of argument, assume that there is zero cloud cover or atmospheric interference. Also assume the camera and mirrors etc. would even work pointed towards the earth instead of away. Bonus points if you can show how you calculated the resolution.

So ET won't be picking up the Olympic Games in 1936 Berlin?

MrMulan — Tue, 12 May 2009 11:18:32 -0800

Do radio waves attenuate and become noise or do they go on forever? In Carl Sagan's Cosmos and his novel Contact, he writes how radio waves go on forever. I just finished seeing the Discovery Planet special "Life after People", where in the closing segment, the narrator states that new research has shown that radio waves probably attenuate after 4 light years to become nothing more than noise. This occurs because of cosmic dust, radiation, planetary systems, asteroids, ect.

I thought radio waves go on indefinitely in a vacuum, and space is mostly a vacuum because of the distances involved, even with all the cosmic dust and whatnot.

So has another cherished belief of mine hit the dustbin?

Hydrogen coalescence in formation of solar system?

Spoonman — Tue, 31 Mar 2009 09:04:38 -0800

I've been rewatching Carl Sagan's Cosmos since I found out it's available on Hulu. Last night, I was watching the episode in which Carl describes how the solar system was formed via the coalescence of particulate matter. But, something struck me as rather odd: if hydrogen and helium are lighter than the heavy elements (duh!) why is it that THEY coalesced into the center of the solar system to become the Sun? It seems to me the heavier elements would migrate towards the center of the maelstrom a bit faster than the lighter ones. Haven't been able to find out the reason for this, hoping the hive can help.

A Pail af Air

dustsquid — Thu, 26 Mar 2009 01:05:45 -0800

I recall reading a thread years ago on alt.astronomy or one of the similar news groups regarding the, "Pail of Air" scenario. The basic idea is, if the sun were to go out tomorrow how long would life on earth survive? The thread had hundreds, perhaps thousands, of posts and lasted for months. Does anyone have a link to a copy of that discussion?

What time should our sunset wedding ceremony start?

dansays — Sat, 21 Mar 2009 11:43:10 -0800

How can I determine at what time the midtown Manhattan skyline will be lit up at sunset on June 20th, 2009? My fiancee and I will be married on June 20th of this year. The ceremony, weather permitting, will be held on a terrace that has a gorgeous view of the midtown skyline, including the Empire State Building.

Assuming clear skies, what time should we plan for the ceremony to start so that the ESB looks like this in our photos?

Unusual music for beautiful space images? No electronic space music, please?

Jennifer S. — Tue, 24 Feb 2009 13:00:56 -0800

Attention music lovers: I’m looking for music to accompany a gorgeous planetarium show about philosophy, cosmology, perception and the known universe. Know any good instrumental music that’d making an interesting and unusual choice to accompany images of distant space? Something Carnatic, Persian…beyond airy space music or Philip Glass?

***

A colleague is doing a talk inside a sort of planetarium (a GeoDome, actually) with a program that models the known, observable universe to its limit.

Here’s some Flickr sets of the visuals accompanying the talk.

He’s currently using airy electronic music which works fine. But I wonder if there isn’t another approach.

I’ve heard that Sergei Eisenstein was inspired to juxtapose images in his movies by seeing Japanese ideograms. An ideogram showing a knife and a heart together, for instance, does not mean murder or violence, but sorrow.

I would like to try to find music that creates a similar effect, and provides a richer context for my colleague’s ideas.

I first thought of Carnatic music, with its ties to ancient Hindu religion, so much more in touch with cosmic timeframes than Western religions. But most of the instrumental Carnatic violin music I’ve found has changes in tempo that don’t make it a good choice for background music.

Ideally, the music should be instrumental, relatively unobtrusive and not have jarring percussion/dissonance/changes in tempo/etc. that would distract listeners significantly away from the speaker. Also, ideally, it’d be downloadable and in the public domain or created by an artist willing to let it be used.

Any ideas? Love to have them! Thanks!

Help a newb astronomer see Comet Lulin from Maryland!

RobotNinja — Mon, 23 Feb 2009 06:49:19 -0800

I am going crazy trying to get a sighting of Comet Lulin, and I don't want to blow the best chance tonight! I live east of Rockville, MD, and there is a fair amount of light pollution in the area. I just got a 6" Dobsonian Telescope (Orion XT6), but know very little about finding my way around the sky. I'm sure I'm looking in the right place, as I've consulted sky charts from spaceweather.com. In early February, I tried waking up around 4am a few times to get a view of the comet in the south-east of Virgo, with no success. Last night I tried at 1am, the current recommended time. I found Saturn and looked a few degrees down and east. Through my binoculars I can see a very, very faint patch of gas, so dim I would pass right over it if I didn't know I was looking for a comet. Through my telescope I see nothing, though. I had a hard time finding focus because I don't know whether that faint patch was really the comet.

Is the core obvious? Will it really look green? I'm not seeing anything like the pictures that are posted on spaceweather. Can anyone give me an idea of what the comet will look like to my eyes through the telescope? Has anyone successfully seen it from a location like mine? Any other generic viewing/finding/focusing tips? I have a Orion XT6 Dobsonian with 25mm and 10mm eyepieces. Can you help a newbie astronomer?

It's not the end of the world...

jasondbarr — Tue, 10 Feb 2009 07:29:34 -0800

Reading this article (and a USA Today story linked in it) this morning, and I'm curious about an astronomical event mentioned in it. So, all of the silliness surrounding the end of the world in 2012 seems to be predicated on the fact that the end of this particular "long cycle" in the Mayan calendar occurs on a winter solstice, and the fact that our sun will align with the center of the Milky Way galaxy on the same day. Apparently, this type of alignment occurs only once every 26,000 years.

What does that mean? I'm not a mathematician or an astronomer, but my understanding is that in Euclidian geometry, two points can be connected to form a line at all times. So, technically, the sun and the center of the galaxy are always "aligned" from this standpoint. And, if we're dealing with this as the sun and the center of the galaxy aligning from the perspective of Earth, it seems like it should happen more often. Since the Earth revolves around the Sun, and the Sun revolves around the center of the galaxy, there have to be plenty of times (once a year, at least) where these three points (Earth, Sun, and Center of Galaxy) line up.

What am I missing? I'm not worried about a cosmic catastrophe, but this seems to me like it should be a fairly common occurrence, and not justification for losing your mind about the apocalypse.

"It was a quarter past two when Moses parted the waters..."

np312 — Tue, 03 Feb 2009 00:32:08 -0800

Are specific times of day ever mentioned in the Old Testament or in its apocryphal writings? I know that somewhere in the New Testament it talks about Jesus doing something on the "9th hour of the 14th day of " etc.

But specifically in the Old Testament, are there any mentions of "noon" or "three hours past dawn" or anything like that? My google-fu is plumb tuckered out.

I'm also interested in any Biblical references to time that come from an astronomical perspective, like if the Old Testament references a particular arrangement of constellations overhead when something was happening.

The more specific you can be, the better! Thanks!

How to calculate positions of stars?

zackola — Wed, 19 Nov 2008 16:11:16 -0800

How do I calculate x,y values for a celestial body using a gnomonic projection? OK, I'm writing some software displays constellations, stars, and other celestial bodies. I have delved into the domain enough that I have a semi-working program. I am able to display the correct stars, at the correct point in time, at a given lat/lng on the Earth. (Sidenote: geez, Mean Sidereal Time is some wacky stuff)

My problem arises though when, given horizontal and vertical field of views, mapping the calculated Altitude and Azimuth (which I've verified is correct) to X,Y points on a 2d screen. Right now, as Altitude of stars increase, there is significant weirdness about what happens to the constellations higher in the sky because right now, I am just mapping straight to the screen using a standard ratio of screen size and fov

I've looked around a bit, and found there are different projections (I think I'm on the right track) that can be used to do this, the most common of which is a Gnomonic Projection (also known as a tangential projection?) but I am not really sure how to apply this to celestial bodies...Maybe I need a geometry lesson...

Any help on where to find equations to calculate these projections would be much appreciated, or advice on what routes to explore...

Leaving Academia after my Phd in Astrophysics

gradstu1980 — Sun, 09 Nov 2008 23:38:01 -0800

Wanting to leave academia after astrophysics PhD (oscillations in atmospheres of rotating starts, planets and discs). Need some feedback, tags, hints, keywords, that I should search in google and some suggestions of where my skills (look in the extended explanation) would be appreciated. After searching the net, there are some jobs I can apply to but given my lack of experience in the industry I'm afraid I won't be able to get any job in few months (before starting to die of hunger).

So I'm gonna mention some of my skills and I would like just few words, hints, whatever, I can type on google and I can see if I may be good doing that in the industry, R&D, IT, NGOs, government, hospitals, you name it.

1.- You give me a differential equation (PDE) and I solve it numerically either using spectral methods (expanding the solution in set of polynomials), or finite differences.

2.- I Program in Fortran (i know, it is obsolete in the industry but my research group used to work on it), C (I used it during my undergrad and before my qualifying exam for everything I needed), perl, mathematica. I guess I am very confident about making any algorithm, so moving towards other program languages could be easy if needed and if employers give me a week or so to study on my own any other.

3.- Used computer clusters; I did basic proccesor2processor communication algorithms, I mainly used the clusters to use lots of processors at the same time thou,without letting them know each other.

4.- As any PhD graduate (I'm being humble :) )from the physical sciences I have strong analytic skills, very strong. I didn't work with statistics, but I can get into them in no time, I understand all the basics, and since I'm good with calculus and algebra and interpretation I think I can get into any statistician job.

5.- Following 4, I can give talks, and work in groups and by mylself.

6.- I know the very basic IT knowledge (although I always had problems remembering the technical terminology), like Linux, Windows (Office, webpage making, excel, etc), latex, hardware, and I can create nice 3d animations using different software.

7.- 3 publications in astrophysics (theory), + thesis, so I guess I can write.

8.- Bilingual (Spanish, English).

Well, that's pretty much it.

I would also want to know if I should apply to entry-level jobs to gain some experience and not to suffer the big crush of the transition. But I'm quite convinced that some of the techniques I was using may be appreciated in the R&D sector, like computational fluid dynamics (aerospace and car industries).

I am really sure to leave Academia, there is no go back, although my research turns out to be a very good contribution for science, I don't have the strength to keep pushing and relocate for a badly payed postdoc, that maybe be working as hard as anyone in the industry. I've been living in poverty since I left high-school and I'm tired of it (I'm 28). I don't feel like I need to be doing science to be happy, just I need to use my brain and I will be happy in any work (that pays reasonably well, but I am not as greedy in order to go to wallsteet and get crazy making money with no life).

And I am very flexible to go everywhere in the world for a job (I am currently in Canada).

So guys, please, where do I start searching.

Thank you very much.

p.d.: I am not willing to get more education (I did educate myself in many areas, my supervisor and colleagues helped very little, so I guess I gain too much confidence in my own learning skills), so no MBA, law or MScs for me, I need to do stuff. After my PhD, degrees means nothing to me (and I guess for employers they mean nothing too), I did it cause I used to love science, but as many others, I got burned, and I got pragmatic with time.

A less Rude planisphere? (southern hemisphere)

jet_silver — Thu, 09 Oct 2008 09:22:36 -0800

What planisphere would you recommend for 15 degrees South latitude? My gf is going to the tropical southern hemisphere. She would like to carry along a planisphere, preferably with constellations and stars +2 magnitude and brighter labeled. The Celestron one appears to be the standard but I cannot tell from online descriptions whether it has the southern hemisphere's stars at all. The Rude Starfinder is too awkward for her to use comfortably. Ideally the planisphere would be plastic since the environment is pretty damp. Have you a recommendation?

the sun sets here

thenormshow — Mon, 29 Sep 2008 08:11:00 -0800

When is Torontohenge? Some of you might be familiar with Manhattanhenge, the phenomena where the sunset is in line with the east-west streets in Manhattan. Much of Toronto's downtown core is on such a grid, although on a different angle, and I'm wondering wether a similar thing will happen here. I tried to calculate this once, but could never get all the variables sorted. Is there an astronomy geek who can help me out?

Fire in the sky

dydecker — Tue, 16 Sep 2008 07:27:03 -0800

This week I saw something very strange in the sky - maybe you can identify what it was. First things first: I am not a nutjob & my girlfriend saw it too so I wasn't imagining things.

The thing came from the west about 30 degrees above the horizon and it took about 3 minutes to fly overhead and then disappear off into the distance the other way. 3 minutes to cross the whole sky. It didn't seem to be falling, more like orbiting. When it was right overhead it was on fire really bright, and pretty big, about the size of a small plane flying at 2000m.

My question is was it a meteor or an asteriod or something else? Also is it common to see things like this? I looked in the newspaper (in Berlin) but there was no mention of it (maybe because it happened at around 4 in the morning)

Is the amount of matter in the universe infinite?

borkingchikapa — Wed, 20 Aug 2008 06:31:31 -0800

Is the amount of matter in the universe infinite, too? How does that work? So, okay, say our universe is infinite (current data supports this, right?). Since there are a finite number of ways that particles can be arranged, that must mean that if you go far enough you'll run into an identical earth with an identical history, identical population, an identical you. Even though that's hella weird and I could probably never explain it to my parents, I think I get it.

I'd heard all that before, but I was listening to this Radiolab podcast (which is really very good!) and it doesn't mention the one thing I never understood - doesn't that mean that the amount of matter in the universe must also be infinite?

Honestly, in light of all this other nonsense, that tidbit wouldn't be that hard to swallow if it didn't directly contradict other weird stuff I've heard. For example, according to this episode of Astronomy Cast (maybe I shouldn't be getting all my information from podcasts), the Big Bang created slightly more matter than anti-matter, resulting in a mostly-matter universe. But how could it be more if matter is infinite? They even give a number, I think it's something like ten billion particles of antimatter to ten billion and one of matter.

Now what? Is matter actually infinite? Is one of those wrong? Are they both supported, and there's something I'm missing?