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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4
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2answers
159 views

Is there a good explanation for the observation of Martian canals?

Martian "canals" have been observed by independent observers after their first description. Now, they are attributed to "optical illusion", but I think that this is not a good choice of word, because ...
8
votes
10answers
172 views

Are there websites or programmes that permit a simulation of the night sky in the past and the future on an ordinary computer?

Are there websites or programs that permit a simulation of the night sky in the past and the future on an ordinary computer? (For the past, I would be content with objects visible to the naked eye.) ...
6
votes
1answer
114 views

How dark does it have to be to see the gegenschein?

I know I've seen zodiacal light, especially at my old club's best dark-site. However, I'm pretty sure I've yet to see the gegenschein. How good does the seeing have to be to be able to see that?
8
votes
1answer
88 views

What size aperature would I need to find and see the supernova in M51?

On June 2, 2011, a new supernova was identified by an amateur French astronomer in M51. What size telescope aperture would one need to have any chance of seeing this? Given the right sized scope, ...
5
votes
1answer
18 views

What criteria were used to set the “useme” flag in the NOMAD astrometric catalog?

How was the value of the "useme" flag in the NOMAD astrometric catalog set? The readme just describes the field as "Recommended astrometric standard," but says nothing about the basis on which that ...
9
votes
2answers
136 views

What are the prerequisites for considering any other planet to be habitable?

Well, there is a measure of how a planet could be considered like Earth, called Planetary habitability. Based on this measure, what are the prerequisites needed to consider a planet to be a habitable ...
7
votes
6answers
2k views

Can any telescope be used for solar observing?

Can any telescope, such as a 8" reflector, that is normally used at night to look at planets be used or adapted for solar observing? What kind of adapters or filters are required or is it better to ...
22
votes
3answers
2k views

How to determine what size telescope to buy

A couple of years ago my son showed an interest in astronomy and we bought a 6" reflector telescope. We use it pretty regularly and have enjoyed it immensely. Lately we've both been wishing we had ...
6
votes
2answers
645 views

Optimal Angular Field of View (AFOV)

Given the rather huge price differences between eye pieces at the same focal length. How exactly does the AFOV affect the view seen through the eyepiece? Are higher / lower AFOV better for certain ...
29
votes
4answers
565 views

Telescopes to avoid as a beginner? [closed]

I've heard people talk about "department store scopes" or "trash scopes". How do I know what to avoid in a beginner scope? How can I know that I'm not getting something we will be more frustrated with ...
11
votes
2answers
108 views

Who should I contact if I see an unknown object in the sky?

Who should I contact if I see an unknown object in the sky? Should I contact the nearest observatory? Or is there some official place run by, say, NASA or ESA that take in observations in their ...
12
votes
5answers
5k views

Does Earth have a code name?

Everything we discover in the sky get eventually a code name, like NGC 7293, Simeis 147, etc. Does Earth/Moon have a code name too? Or it is just Earth/Moon, etc.?
4
votes
2answers
422 views

Resources and requirements for amateur spectroscopy

If I wanted to move beyond just looking through my eyepieces and taking photographs of astronomical objects, what can I do do move into astronomical spectroscopy? Are there any good resources for ...
8
votes
2answers
874 views

Is there any evidence for the claim that the moon was once part of the Earth?

There is a hypothesis that says a part of the Earth was split away and became the Moon. Is there any scientific evidence for this claim?
4
votes
1answer
939 views

What are the pros and cons of a german equatorial mount vs. a fork mount?

Not much more to add. Why pick one over another?
7
votes
1answer
103 views

What is a backlit CCD sensor, and why might I prefer it to other kinds?

I've heard Astronomers talking about backlit CCD sensors, and talking about how much better they are than other types. What are they, why might I want to get one, and what are the pros/cons of this ...
7
votes
1answer
20 views

What tools do I need to track an orbit of a mystery object?

A while back I was observing Uranus with my 6" dob and a moving object tracked across my field of view. I was at about 90x at the time, and the object was pretty bright but slow moving. I dropped down ...
6
votes
2answers
42 views

Scientific value of timing total lunar occultations

Is there still scientific value in timing and reporting total lunar occultations? Why would I time total lunar occultations (grazing occultations are out of the question)? When I reported ...
15
votes
3answers
4k views

Observing lunar lander and footprints on the moon?

After Apollo 11 first landed on the Moon in 1969, there have been conspiracy theories that this never really happened and that it was all a hoax. In 2010 NASA released photos from its Lunar ...
5
votes
1answer
271 views

A method to estimate the relative magnitude of a star using nearby stars

I remember a method to make a reasonable estimate of the magnitude of a given star X by using two other stars of known magnitude as references. The method used evaluation phrases like "the star X and ...
13
votes
5answers
4k views

Where can I find public domain astronomical pictures?

Where can I find public domain astronomical pictures of nebulae, stars, etc. that can be freely used?
2
votes
2answers
65 views

What objects look best in an O-III filter?

I've heard that an O-III (Oxygen III) filter is great for planetary nebulae. Is this true for all planetary nebulae, or just some or most? What other target types are often improved with an O-III ...
9
votes
3answers
30 views

What are good resources for someone looking to become an amateur astronomer?

What resources would you consider to be essential for an amateur astronomer?
-1
votes
3answers
390 views

What age to start kids with astronomy [closed]

My son is getting interested in astronomy. I was thinking about getting him a scope when he gets a bit older, he is 4 now. At what age have other people gotten their kids telescopes? (I have a 10" dob ...
7
votes
3answers
5k views

How are Cepheids used to evaluate their distance?

Cepheids are used to evaluate distances. What is the math and physics behind their use?
10
votes
3answers
238 views

Why is M42 red in the pictures, but green when observed at the eyepiece?

I saw magnificent images of the Orion Nebula (M42) in pictures from Wikipedia, However, when observed with a telescope, the nebula appears green hued, and I can't see any of the characteristic red ...
8
votes
1answer
1k views

For observing planets what kind of telescope offers the best view?

I've heard that using a refractor is better than a reflector when it comes to planets to best reproduce their colors. But perhaps other factors can weight in too? For example, do you want a slow or ...
12
votes
3answers
90 views

Which is the strongest meteor shower expected in the next years in the Northern hemisphere?

Which is the strongest meteor shower expected in the next years in the Northern hemisphere? Is it possible to give good predictions for this?
6
votes
2answers
144 views

How can I judge a globular cluster on the Shapley & Sawyer scale?

Globular clusters were classified by Shapley and Sawyer as being on a scale from 1 to 12 where 1 is very loosely packed central area and 12 is highly packed central area. As a visual astronomer, it ...
8
votes
2answers
1k views

What is exactly a Dobsonian, and what are the differences when compared with Schmidt-Cassegrain or Newtonian?

What is exactly a Dobsonian telescope, and what are the differences between this technical choice over a Schmidt-Cassegrain or a Newtonian configurations?
0
votes
4answers
2k views

What is the typical career path to become a professional Astronomer? [closed]

Here is a typical question which I have been asked many times while giving public lectures in various places. While I know one of the paths like Diploma, Masters and PhD but sometimes this is not so ...
11
votes
4answers
8k views

What does f/4.6 mean in a telescope and how important is this value? [closed]

In some specifications for telescopes, I saw a value marked as f/4.6. What does it mean exactly, and how important is when it comes to choosing a telescope?
8
votes
1answer
148 views

Best periods to observe Magellanic Clouds?

When is the best period of the year to observe the LMC and SMC in the Southern hemisphere, so that I can observe them at a reasonable time (e.g. around 10 in the evening?). I am in Sydney.
0
votes
2answers
196 views

Gyrochronology, the formula is empirical ?

The formula used in Gyrochronology that relates a star's Period of Rotation-Mass-Age is empirical? This news How to Learn a Star’s True Age "“A star’s rotation slows down steadily with time, ...
2
votes
3answers
222 views

What is the strange event in this simulation of a galactic collision?

I was watching this video on YouTube: 2 Spiral Galaxies w/Supermassive Black Holes Collide Around half way, and again almost at the end, the black holes seem to suddenly give off some sort of force ...
4
votes
2answers
145 views

What really are some distant astronomical bodies that seems like dust clouds?

Looking at pictures like this I bet it is a picture of a giant cloud of dust, bigger than a galaxy and made of asteroids and planets (instead of stars). But probably I'm wrong. What is that?
2
votes
1answer
556 views

IRIS alternative on mac?

I need to process some images taken from a telescope to determine the intensity of an astroid. This way I can determine the rotation period of this asteroid. The pictures were taken the usual way ...
3
votes
2answers
4k views

Glycerol: refractive index & absorption spectra in 0.2-0.4um range

Could anyone suggest where can I find absorption spectra & refractive index of Glycerol? I am specifically interested in UV range, 200-400nm, everything I was able to find out was for standard ...
0
votes
1answer
174 views

What is 656 Beagle?

What kind of object is 656 Beagle (1908BU)? I know it's a minor planet, but that includes a large array of different stuff. Specifically, I am looking at the general chemistry/geology of the object.
2
votes
2answers
884 views

What is meant by positive and negative gravity/energy/spactimecurvature?

I have recently come across some cosmological assertions (based on empirical data) about the universe being self contained in the sense that it is entirely capable of coming into existence from a ...
7
votes
3answers
517 views

Are there planetary systems where the planes of orbits vary greatly?

Inspired by this question, are there any known planetary systems with largely varying planes of orbit? For example a system where two planets have perpendicular planes?
5
votes
1answer
156 views

Oort Cloud Detection

The hypothetical Oort cloud is an explaination for long period comets. It presumably is made up of icy bodies orbiting up to 50,000 AU from the Sun. If so, shouldn't the Spitzer IR telescope have ...
1
vote
0answers
226 views

Is the conclusion that the cosmic burst observed in the Draco constellation from gamma rays that are streaming towards a massive black hole correct?

Referencing this news article: http://www.smh.com.au/technology/sci-tech/cosmic-burst-in-far-away-galaxy-puzzles-nasa-20110408-1d6kz.html It also references an event id: (GRB) 110328A The article ...
2
votes
1answer
126 views

Solar Cycle UV Variation

The average energy we receive from the Sun is 1,366 w/m^2, and this only varies by 0.1% from the activity peak to trough of its 11 year cycle. About 9% of the energy comes from wavelengths less than ...
-2
votes
5answers
288 views

Does the rotational speed of a planet consistently become faster and faster given that there are no conflicting events? [closed]

Does the rotational speed of a planet consistently become faster and faster given that there are no conflicting events?
4
votes
1answer
1k views

Gravity and Planetary Differentiation

During solar system formation, many bodies achieved hydrostatic equilibrium, a spherical shape where their self gravitational force was balanced by internal pressure. Many also achieved ...
11
votes
4answers
5k views

Why does Venus rotate the opposite direction as other planets?

Given: Law of Conservation of Angular Momentum. Reverse spinning with dense atmosphere (92 times > Earth & CO2 dominant sulphur based). Surface same degree of aging all over. Hypothetical large ...
7
votes
1answer
227 views

Mass Needed to Clear an Orbital Neighborhood

In 2006 the IAU deemed that Pluto was no longer a planet because it fails to "clear" the neighborhood around its Kuiper Belt orbit. Presumably, this is because Pluto (1.305E22 kg) has insufficient ...
5
votes
2answers
308 views

Does the math work out for there being enough time for the formation of the heavier elements and their distribution as seen in today's universe?

Currently accepted scientific theory says that all elements heavier than hydrogen, helium, and a little lithium have been created in supernova explosions. My questions, specifically, is has anyone ...
1
vote
4answers
9k views

How does the moon reflect light?

We can see the moon in the night because it reflects sunlight. But the light is incident on the opposite side of moon with respect to the observer in the night. In this case, how does the moon ...