The science dealing with objects and phenomena located beyond Earth. In particular, this applies to observations and data. At its core, astronomy is the physically informed cataloging and classifying of the contents of the universe in order to better understand what is out there.

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November 25th 2011 partial solar eclipse visibility from Christchurch, New Zealand

Where can I find a site that will give me an indication of coverage for the November 25th 2011 partial solar eclipse as viewed from Christchurch, New Zealand tonight, as well as local times for the ...
6
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1answer
93 views

Detecting dim objects

What are the minimum conditions (switching times, sensitivity ...) for a camera to detect dim objects, e.g. Oort cloud or Kuiper belt objects, passing by in front of a star in the background? I've ...
6
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1answer
131 views

Is the Apophis asteroid a concern?

I was watching the TED lecture How to defend Earth from asteroids , and the speaker Phil Plait spoke of the possibility of this asteroid hitting Earth. He also said something about a Mayan legend. He ...
6
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1answer
33 views

Liquid Water in “mid-ice” on Europa. Mechanism?

Recently I read this entry by Dr. Phil Plait (a.k.a. The Bad Astronomer). He is talking about a lake of water contained within the ice layer of Europa. the lake is completely embedded in the ice ...
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1answer
531 views

Calculating position using shadows

Suppose, we know the length of the shadow of an object at some known time. Can we use the this information to find position of the object (the longitude )?
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1answer
90 views

Shadow of a Jovian moon over the Great Red Spot

Where can I find pictures of the shadow of any of the Jovian moons partially covering the Great Red Spot? A series of such pictures over time would even be better. The idea is to learn more about the ...
2
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2answers
148 views

Best time of the year to see the star Alpha Centauri in Chile, Santiago

If I'm in Chile, Santiago, what is the best time of the year to see the star Alpha Centauri at the beginning of the night?
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1answer
62 views

Is it possible to check from the EM waves(basically Light rays)?

Is it possible to check from the EM waves(basically Light rays), if there are any extraterrestrial objects interference/passage during its travel from the Sun? I mean, can these EMs from the Sun be ...
10
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2answers
247 views

Why did population III stars lack planets?

Jay Wacker1 (professor of physics at the SLAC National Accelerator Laboratory) stated: The first stars (known as Pop III) were made out of hydrogen and helium. They had no planets. Why couldn't ...
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2answers
226 views

How do I find the time for Pleiades to be at Zenith today

I am looking for a way find the time when: Pleiades will be at the Zenith today (11th November 2011) Pleiades will conjunct with the Moon The Moon will be at the Zenith today How do I find those ...
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3answers
2k views

Use of advanced mathematics in astronomy, like topology, abstract algebra, or others

I know that topology, abstract algebra, K-theory, Riemannian geometry and others, can be used in physics. Are some of these areas used in astronomy, and are some astronomical theories based on them? ...
9
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2answers
514 views

Where does the dust on the moon come from?

From the Apollo missions we know that the moon is covered with dust. Where does it come from? Is it from the erosion of the moon rock? By what? Or by accretion of dust from space? Which comes from ...
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1answer
61 views

Transit of Mercury: how did he see it?

On November 7, 1631 Pierre Gassendi saw the transit of Mercury across the face of the Sun. How did he see it? I mean what instrument was used to reduce the apparent brightness of the Sun?
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1answer
19 views

Are there trends in the number of meteors in a shower year on year?

Some years the Leonids are amazing, other years there are very few - are these predictable at all, following trends or at least reasonably accurate predictions?
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3answers
43 views

Where can I find a list of when I can see something in the sky?

My son is very keen on Astronomy but I don't know when there are meteor showers or something else that would be worth going out to the country to see. Last year we went to see a meteor shower, but I ...
4
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2answers
39 views

How bright will an asteroid be?

In the news, it has been stated that there will be a fairly large asteroid passing fairly close to Earth soon. I've been trying to find a good observation guide, including determining how bright it ...
7
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1answer
109 views

What's the most accepted theory for Blue Stragglers These Days?

I'm working on a post against a recent creationism article about blue stragglers. From when I was in undergrad, the general explanation was that they were likely second generation stars within ...
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2answers
948 views

What is a good introductory text to astronomy [closed]

What is a good and easy to read introductory text for an adult with limited basic scientific knowledge to astronomy for someone without a telescope and lives in a big city and why do you think that ...
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2answers
61 views

Does Mercury have a balmy spot?

From Wikipedia: Although the daylight temperature at the surface of Mercury is generally extremely high, observations strongly suggest that ice exists on Mercury. Does that mean there could be a ...
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3answers
1k views

Why is this radio telescope's reflector spherical and not parabolic?

This is the Arecibo Observatory in Arecibo, Puerto Rico. Its reflector is spherical, measuring 1,001 ft. in diameter. It is considered the most sensitive radio telescope on Earth, but the fact that ...
4
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1answer
224 views

Why isn't sunset time in sync with solstice?

The winter solstice in the Northern Hemisphere in 2011 is on December 22. But if I look at the sunset times for a location such as Washington, DC on the USNO site, the sunset time starts reversing ...
2
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1answer
144 views

Get time from sun Azimuth

I want to know if I can determine the time where the sun's azimuth is at a given value. In other words, I want a function that takes the sun azimuth along with longitude or time zone and outputs the ...
16
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1answer
4k views

Which way do spiral galaxies rotate?

Is it known whether spiral galaxies typically (or exclusively?) rotate with the arms trailing or facing? Intuitively it feels weird to think of the arms as facing the direction of rotation, but ...
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2answers
342 views

How fast is the Cosmic Microwave Background Radiation (CMBR) changing?

I know that the Cosmic Microwave Background Radiation (CMBR) is the leftover radiation from the "surface of last scattering". However, at every instant the surface is changing (at the rate of flow ...
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0answers
187 views

Parallax Cloud Displacement - Angular Distance from Geostationary Satellite

When observing clouds from a geostationary satellite, they appear displaced because of the parallax effect. The satellite looks at the clouds "at an angle" and it projects them on a point of the earth ...
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1answer
112 views

How is the atmosphere composition of astronomical objects in solar system determined?

How is the atmosphere composition of astronomical objects, for example triton, the moon of neptune, determined?
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2answers
4k views

How much of sky can be seen on a typical night from a mid-latitude location?

I'm at about 40deg north so, assuming a clear southern horizon, I can't see things below about -30 or so (I actually don't know how far south). I also have a large portion that is circumpolar so it's ...
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1answer
77 views

What could this very dark planet be made of?

I was reading about the planet TrES-2b which is less reflective than charcoal. What could possibly be its composition?
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3answers
528 views

Pleiades through a 15x 76 mm telescope

How clearly can the stars of the Pleiades cluster be seen through a 15x telescope (for example, FunScope)?
7
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1answer
2k views

What are the minimum telescope requirements to view a nice spiral galaxy?

I would like to view some spiral galaxy. However, I would prefer not to spend lots of $$$. What are the minimum specs a telescope must have to resolve detail in a spiral galaxy?
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3answers
274 views

Name for celestial “Prime Meridian”?

Is there name for the line that goes from celestial pole to pole at RA 0 degrees 0 minutes 0 seconds? On Earth we would call it the Prime Meridian. Is it called the "Celestial Meridian"?
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2answers
3k views

Density of stars near the center of the Milky Way

At night, I can look up and see the Milky Way across the sky. My question is, supposing our solar system was, instead of way out on an 'arm' of the galaxy, if we were near the galactic center. Would ...
14
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5answers
4k views

Telescope for 6 year old and dad new to astronomy

What's a good telescope for my 6 year old? We're both brand new to telescopes in general, but love space, stars, planets, cosmology, etc. Happy to spend up to $200 to start. Maybe more for a good ...
6
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1answer
1k views

Is there a simple yet accurate formula for where on Earth the Sun and Moon are directly overhead?

I'm trying to improve a site that shows the region of the Earth currently under daylight, and I need a formula that, given the current time, tells where (latitude/longitude) the sun and moon are ...
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2answers
98 views

Tropical year is 27s/year off from Gregorian year?

http://hpiers.obspm.fr/eop-pc/models/constants.html states the tropical year is $365.242190402$ days. The Gregorian calendar's average year is $365.2425$ days (every 4th year a leap year, except ...
4
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1answer
27 views

What demonstrations for a five-hour optical and radio astronomy workshop? [closed]

I volunteer at a group that has restored the oldest German radio telescope. We are now at a point where we want to invite interested amateur astronomers and school children to workshops. I'm currently ...
20
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2answers
618 views

Why don't stars in globular clusters all orbit in the same plane?

Globular clusters like Omega Centauri certainly don't seem to be very coplanar at all. In other words, why doesn't the explanation at Why are our planets in the solar system all on the same ...
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1answer
47 views

Where to get hard historical and trend data related to reentry of satellites like UARS [closed]

NASA is providing very brief updates on the reentry of the UARS satellite. They also published an extensive study of the Re-entry and risk assessment for the NASA Upper Atmosphere Research Satellite ...
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3answers
754 views

What is the minimum magnification needed for an instrument to see all the Messier objects?

I know someone that wants to buy a 60cm (1.5 inch) refractor and I thought about recommending what to look at the Messier objects. And I was wondering, can he see all these objects with that refractor ...
0
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3answers
239 views

Why is it hard to write a computer program to detect patterns which planethunters is asking us to figure out? [closed]

I recently came across this site http://www.planethunters.org. It shows brightness observed for a star vs time. It asks questions like if star is exhibiting variable or fixed pattern. Later it asks if ...
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3answers
574 views

“Reverse engineering” of a horoscope?

I'll start with a disclaimer -- this is not a question about astrology itself, I'm neither trying to refute nor to defend astrology. I'm interested in purely technical things, which are mostly ...
4
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3answers
259 views

Fall/Winter Viewing

I live in Seattle and am thinking of purchasing a telescope. Is fall/winter a decent time of year for viewing (aside from summer)? Are there any major viewings/events during that this of year? I know ...
-1
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2answers
5k views

Celestron NexStar 6 SE vs. Orion XT8 [closed]

I'm interested in purchasing a new telescope and have narrowed it down to the NexStar 6 SE vs. the Orion XT8. I'd like to be able to get into astrophotography and read that having the Go-To ...
3
votes
3answers
148 views

Photographs of galaxies many light years far from the Earth

Using ground-based telescopes or the Hubble Space Telescope, astronomers take photographs of galaxies which are many light years from the Earth. Does it mean those photographs are as old as the ...
8
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3answers
1k views

Are planetary orbits measured from the Sun's surface or centre?

I would imagine planetary orbits are measured from the Sun's centre and not its surface. Is that true? I can't find anywhere that actually states this.
0
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3answers
66 views

Why can't Jupiter be seen over Thanksgiving break?

As of these past few days, Jupiter can be seen in the sky, correct? Around Thanksgiving, why can't it be seen?
2
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2answers
55 views

What physical interactions actually make single stars leave their binary companions at formation?

From an interesting ScienceDaily article, I read this Before the groups of stars disperse, binary stars move through their birth sites and the group studied how they interact with other stars ...
0
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1answer
277 views

Is water necessary for forming the sedimentary rocks found on Mars' surface?

So, I've just been reading a recent ScienceDaily article, and came across this interesting quote "Clays form in more neutral, less acidic conditions than the sulfate-rich sandstones we've been ...
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1answer
2k views

How vacuous is intergalactic space?

You often hear intergalactic space is an example for a very good vacuum. But how vacuos is space between galaxy clusters and inside a huge void structure? Are there papers quoting a ...
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2answers
707 views

What percent of planets are in the position that they could be viewed edge-on from Earth? (and thus able to undergo transits)

Star number 12644769 from the Kepler Input Catalog was identified as an eclipsing binary with a 41-day period, from the detection of its mutual eclipses (9). Eclipses occur because the orbital ...