6
votes
1answer
68 views

Calculation of Horizontal Coordinates

Given a fixed coordinate location on Earth (i.e. a latitude and longitude), and a fixed equatorial coordinate location of a particular astronomical object in the sky (i.e. right ascension and ...
6
votes
1answer
72 views

What are the current accepted theories of the formation of the Uranian moon Miranda?

Miranda, a moon of Uranus is unique in that it has a very fractured surface Source: University of Oregon The surface is said to be jagged and fractured, with comparatively large disjointed cliffs ...
5
votes
3answers
127 views

Is there a ceiling for stable L4 or L5 masses?

L4 and L5, the Lagrange points 60 degrees leading and trailing an orbiting body, are famous for being stable. A well known example are the Trojan aseroids at the Sun Jupiter L4 and L5. Nodding to ...
5
votes
1answer
192 views

What's a good step up from 7x50 binoculars?

I own a Nikon OceanPro 7x50 pair of binoculars, but I find that when I look at the moon, I would like more magnification. My requirements are: costs less than $400 weighs less than 10kg the length ...
4
votes
4answers
1k views

Would an exoplanet without axial tilt have no seasons?

Would an Earth analog exoplanet which rotates around a solar analog, but without axial tilt, have no seasons? Would it be similar to how Los Angeles does not have very noticeable seasons compared to ...
4
votes
3answers
199 views

Is there enough hydrogen left after a star dies so another star will have enough to light up?

A star consumes quite a lot of hydrogen in its life, and is pretty much "vacuuming" everything in its vicinity. After it dies (eventually by supernova which will spread all its composition over light ...
4
votes
1answer
294 views

When will the Milky Way “arrive” at the Great Attractor, and what all happen then?

The Great Attractor is described as a location to towards which the Milky Way, along with all other galaxies in the Laniakea Supercluster are moving. How long will it take for the Milky Way to ...
4
votes
1answer
108 views

Any cheap (less than 100 euro) telescope for observing Jupiter? [closed]

The moon is not challenging. I would like to observe the big planets and their rings.
3
votes
1answer
119 views

Where did this famous Planetary Precession Formula come from?

The following equation (which I shall term the Planetary Precession Formula, PPF for short) famously appeared in a 1915 publication by Einstein where he indicated how it could be derived from his ...
3
votes
2answers
1k views

How to calculate Longitude from Right Ascension?

Considering that a star of certain declination is crossing the local meridian at the observer's zenith at an unknown location on the earth. Here, the declination of the star is equal to the observer's ...
2
votes
1answer
39 views

brown dwarfs and planets

As far as I know, a brown dwarf is a 'star' whose core never underwent a fusion reaction, so it never became a star. So I was wondering if, appart from orbiting a star, is there any difference between ...
2
votes
4answers
70 views

Can objects enter hydrostatic equillibrium through processes other than the influence of gravity?

Wouldn't a droplet of liquid (say water) floating around in space become spherical and "in hydrostatic equilibrium" due to surface tension but not gravity?
2
votes
1answer
52 views

Star System Formation questions

I'm making a game in which I'd like to randomly generate star systems. Which is cool. The trouble I'm having is working out exactly what limits I need to place on the generation. So far, the ...
2
votes
1answer
49 views

What is the ratio of cosmic microwave background radiation to normal radiation?

I would like to know the ratio of cosmic microwave background radiation to normal radiation in the universe. I am considering cosmic microwave background radiation to include the microwave, and any ...
1
vote
2answers
119 views

Is it possible that the Sun has a binary partner (the Nemesis Theory) that has eluded detection?

I just recently learned about the theory that our Sun has a small companion star with a 26 million year orbit. This theory came about when it was realized that mass extinction events happened ...
1
vote
3answers
166 views

Can there be an infinity of stars in the Universe?

I have a mind puzzle. Can there be an infinity of stars in the Universe ? I have 2 opposed reasonings, yet I don’t find any flaw in them. Can you help me here ? Answer A : No, the number of stars ...
1
vote
1answer
156 views

Please Guide me to buy my first Telescope [duplicate]

I am a beginner and I've planned to buy a telescope(Newtonian reflector)for viewing planets and deep sky objects. As far as I know the most important factor to get a brighter view is that the ...
1
vote
2answers
139 views

Contradict the expansion of the universe?

Lets say that we observe in a distant galaxy cluster, which in all the galaxies move far away from us. and here we see in the same cluster a galaxy that move away from us in a much lower velocity ...
-2
votes
3answers
158 views

Does the Sun turn around a big star?

The moon turns around the Earth. The Earth turns around the Sun. Does the Sun turn around a big star? If so, does this big star turn around a very big star? ... etc ... What are all the intermediate ...
16
votes
4answers
4k views

If Jupiter is a gas-giant then why don't its features change?

A naive question. When we look at Jupiter, we see that its features didn't change largely over many years, for instance, the red-spot. If it is composed of gases and liquids, then why aren't the ...
14
votes
1answer
684 views

What does it mean for a star to go nova or supernova? Can I safely observe these?

What does it mean for a star when people say it goes 'nova' or super nova, what are the differences? More importantly, can I safely observe these with an amateur telescope? I imagine they would be ...
14
votes
1answer
150 views

Why is the Sun's atmosphere (the corona) so hot?

The visible surface of the Sun is 6000 degrees Celsius but the gas in the solar corona is at least 1 million degrees. What heats the solar corona?
12
votes
1answer
281 views

Why did the Comet Shoemaker-Levy-9 fragments cause such large explosions on Jupiter?

In July 1994, the comet Shoemaker-Levy 9 (D/1993 F2) tidally fragmented and these fragments collided into Jupiter, as per the image below. Image source The question is, what mechanisms resulted in ...
12
votes
2answers
2k views

Does the Moon have any oxygen in its atmosphere?

Since the moon has gravity, it's almost impossible that there aren't some gasses trapped on the surface by the moon's gravity. Has any free-floating oxygen been found on the Moon? If so, in what ...
11
votes
2answers
762 views

Do other planets in our solar system experience eclipses or is this unique to Earth?

Here on Earth we get to experience lunar and solar eclipses. Is this pure coincidence that everything happens to line up? Do other planets in the solar system experience this phenomenon or is this ...
10
votes
2answers
145 views

Might Oort cloud comets be exchanged between solar systems?

Considering their distance from their parent stars, might Oort cloud object such as comets be exchanged between passing stars (assuming that other stars have similar Oort clouds)?
10
votes
2answers
146 views

What is radiation pressure and how does it prevent a star from forming?

This is a follow up to: Is there a theoretical maximum size limit for a star? The answer there talks about the radiation pressure preventing a star from forming. What reaction is causing this ...
10
votes
1answer
316 views

Determining effect of small variable force on planetary perihelion precession

Is there an analytical technique for determining the effect of a small variable transverse acceleration upon the rate of aspides precession (strictly not a precession but rotation of the line of ...
10
votes
1answer
117 views

What are the current observational constraints on the existence of Nemesis?

Nemesis is a hypothetical companion to the Sun on a very eccentric, long-period orbit. The star supposedly returns every few tens of millions years, driving comets into the inner solar system and ...
10
votes
1answer
131 views

Why does the Moon seem larger when it is close to the horizon? [duplicate]

I've noticed that when I look into the sky at night, sometimes the moon appears very large near the horizon. Sometimes it also looks like it has a yellow tint. Is this the light rays bouncing off ...
10
votes
2answers
161 views

What is the upper and lower limit of temperatures found on stars?

What are the most extreme temperatures (both hot and cold) stars have been detected at? Is there an upper and lower limit for the detected temperature of stars?
9
votes
8answers
979 views

What's the largest non-spherical astronomical object in the universe?

Some asteroids and comets are non-spherical. But is the nature of big things and gravity so that large things in the universe are always spherical? What is the biggest astronomical object in terms of ...
9
votes
1answer
123 views

What is the predominant element in the dust of the Sombrero Galaxy?

The Sombrero Galaxy contains a rather peculiar ring of dust orbiting it (seen as the dark ring on the outer edge). What is the prevalent element in this dust? Carbon?
9
votes
1answer
158 views

Parking a telescope at a Lagrange point: is this a good idea from a debris point of view?

The James Webb space telescope is supposed to be located at the Earth-Sun L2 Lagrange point. Do we expect the region around that point to have a higher concentration of space debris, asteroids, ...
8
votes
3answers
199 views

Planets and Pluto? Neptune?

If one of the rules to be a planet is that it needs to clear ALL objects from their orbit, does this also make Neptune a non-planet? Since it has thus far failed to clear Pluto (and based on an answer ...
8
votes
3answers
452 views

Where does the Milky Way end?

I was reading this article and it says the following: Researchers measured the mass of the Milky Way and found that our galaxy is approximately half the weight of a neighbouring galaxy known as ...
8
votes
2answers
196 views

Why are most lunar maria on the visible side?

Is there any reason why the Earth side of the Moon has enormous plains and mountains, while the far side contains just few small ones inside largest craters?
8
votes
1answer
177 views

How do we know Milky Way is a 'barred' spiral galaxy?

In reference to the question, "How can we tell that the milky way is a spiral galaxy?" The answers there clearly sum up the question asked. But Milky Way is not just a spiral galaxy. It is further ...
8
votes
1answer
90 views

What implications do younger Earth and Moon have on Late Heavy Bombardment genesis hypotheses?

The Late Heavy Bombardment (LHB) or the Lunar Cataclysm is when the inner solar system, including the Earth and the Moon, underwent multiple and sustained heavy impacts early in their history (around ...
7
votes
1answer
109 views

Is Earth's orbital eccentricity enough to cause even minor seasons, without axial tilt?

I was reading the answers to this question about an exoplanet having seasons without axial tilt, and several responders mention that orbital eccentricity could cause a similar effect, but that the ...
7
votes
2answers
947 views

Can two comets travel together as one?

If two comets come together in space, will they bounce apart, merge into a single body, or could they travel together through space, either touching or orbiting a shared center of gravity?
7
votes
1answer
259 views

Why does Pluto's Orbit underlap Neptune's Orbit

Why does Pluto's Orbit underlap inside of Neptunes Orbit. Clearly Neptunes Orbit is not overlapping on Pluto's. Yet, they fail to maintain the symmetric banding appearance all the other Planets ...
7
votes
1answer
38 views

Long term development of Comets

When an exocomet passes by our Sun in a trajectory that leads it to establish a Solar Orbit what eventually happens to it? In addition to its original inertia and vector being altered what are the ...
7
votes
1answer
92 views

Effect of Charon on Pluto

Even though Pluto is not known as a planet anymore, theroetically it has/had a moon, called Charon. I've heard about something that their size are so close to each other that while Charon rotates ...
7
votes
1answer
639 views

How does moonrise/moonset azimuth vary with time?

In my tenacious attempts to observe moonrise (surprisingly difficult in a poor weather heavily urbanized hilly area with frequent bad smog, with busy work schedule and a bicycle) I was frequently ...
7
votes
1answer
260 views

Why does the moon sometimes appear giant and a orange red color near the horizon?

I've read various ideas about why the moon looks larger on the horizon. The most reasonable one in my opinion is that it is due to how our brain calculates (perceives) distance, with objects high ...
7
votes
3answers
143 views

What qualifies as a good place for stargazing, i.e. with least light pollution?

I know that minimal light pollution is a must for stargazing, and a place which is away from civilization is better. Does altitude of a place matter for light pollution? Does it affect the quality ...
7
votes
1answer
101 views

How many stars can stay close to each other without collapsing?

Is it possible for two stars to exist close to each other? "Close" is relative; let's assume that two stars are close to each other if they are at the center of the same solar system. It's ...
6
votes
3answers
214 views

Can you explain the pattern of Hill sphere sizes of the objects of the Solar system?

I found this image on calculations of Hill sphere for planets/dwarf planets of the Solar system. From http://en.wikipedia.org/wiki/File:Hill_sphere_of_the_planets.png I found it interesting that ...
6
votes
4answers
231 views

The Existence of Natural Satellites in Geostationary Orbits

While browsing through Physics SE, I noticed a question about satellites in geostationary orbit (unrelated to the one I'm asking here), and for a moment I interpreted it as referring to natural ...

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