1
vote
2answers
60 views

L4 and L5 stability

For what I know, L4 and L5 are high points. Although, they are stable points. Why? I thought it was the same being a high point and being a unstable point. If I'm off-topic, please let me know where ...
1
vote
1answer
60 views

How is the heat production inside moons compliant with Conservation of Energy?

A Nova episode said that during stages of some moons' elliptical orbits, the moon is stretched, and friction causes the inside of the moon to heat up. I do not understand how this is compliant with ...
0
votes
1answer
67 views

Which force makes planets to continuously revolve around their parent star?

We know that planets revolve around their parent star (or specifically Barycenter), they maintain a specific speed of revolution so that they don't end up smashing into their planet star. Which force ...
5
votes
1answer
141 views

What if our galaxy didn't have a SMBH?

From my understanding, it is believed that almost every big galaxy and especially spiral galaxies have supermassive black holes (SMBH's) at the center. Also, from what I've read, a SMBH isn't required ...
2
votes
1answer
42 views

What measure should I use to help optimise the design of a telescope in a cubesat?

I have started a project in Melbourne, Australia called nanosat eye in the sky to put a telescope in a cubesat and put it in LEO. The idea is then to add the telescope to itelescope. I need to learn ...
-1
votes
1answer
69 views

Radial Density Profile Equation [closed]

The Virgo Galaxy Cluster has a mass of $10^{14} M_{\odot}$ and its centre is $16Mpc$ from Earth. The large elliptical galaxy $M87$ lies at the centre of the Virgo cluster. $M87$ has a supermassive ...
1
vote
1answer
29 views

Meteors made of differing substances. Will they all burn up?

If an object enters Earth's atmosphere, what determines whether it burns up or not? Example A feather is released from a space-ship 30,000 km away from Earth and falls under the influence of Earth's ...
1
vote
1answer
30 views

Elemental abundances in the crust of exoplanets and accessibility to them

Suppose I am orbiting a rocky planet (density = 4.4 g/cm3) two-thirds the mass of Mars in the Habitable Zone of Gliese 251. This planet has a thin atmosphere, presumably from out-gassing, still has ...
2
votes
1answer
217 views

What is the largest hydrogen-burning star?

I am wondering what is the largest known core hydrogen-burning star? A look at the list of largest known stars on Wikipedia seems to indicate VV Cephei B (at the bottom of the list), but I would like ...
4
votes
2answers
118 views

Gravitational lensing in Newtonian physics

Famously, when Eddington attempted to measure gravitational lensing during the Eclipse, it was the measured magnitude of the lensing that gave gravity [pun, obviously, intended] to General Relativity ...
1
vote
1answer
436 views

What is a Galactic Eclipse?

It is said that when our solar system passes through the dark rift of galaxy (what is it exactly?), a phenomenon named 'Galactic Eclipse' happens, when our solar system witnesses 3 days of darkness. ...
2
votes
1answer
110 views

Are galaxies moving away with constant acceleration?

Suppose that we could measure the current acceleration with respect to us of a distant galaxy chosen at random in our observable universe (Ignore the peculiar motion of the galaxy). Is the ...
1
vote
1answer
66 views

What's the significance of finding neon on lunar atmospehere? new explanation of moon light?

Now that NASA's LADEE spacecraft has confirmed the presence of Neon in the moon's atmosphere could the official explanation of the moon's light end up being change from reflecting the sun's light to ...
3
votes
1answer
29 views

Standard conditions for a heliacal rising

I imagine there are several possible conditions for determining the time of a helical rising of a star, the elevation of the star at sunrise, the latitude of the observer, and the azimuth of the star. ...
1
vote
3answers
71 views

Is it just the observable universe that is expanding?

Is it possible that it is just our observable part of the universe that is expanding, in the time that we exist, and other parts are both expanding and contracting at different rates and times? Would ...
0
votes
1answer
115 views

Did Big Bang sound as loud as we think?

As we all know, There is no sound in space, because sound waves don't travel in a vacuum. But even if Big Bang did sound, what was the main source of it's cause?
1
vote
1answer
146 views

Looking for planetary position calculation

In Hindu astrology, for creating horoscopes (birth charts), I am looking for calculations of planetary positions. So, how could I calculate planetary positions according to given date, time and place? ...
1
vote
1answer
49 views

What is the mass limit in a stellar accretion disc?

I became curious about the maximum mass in a star's accretion disc while watching an episode of Star Trek involving a Dyson Sphere. I wondered if some maximum amount of stellar material would limit ...
1
vote
2answers
80 views

How does 'centre of mass' concept work?

We know that two celestial bodies rotate around a center of mass. How does this concept work in case of solar systems where there are several planets versus one/two stars? (Even if the center of mass ...
4
votes
1answer
89 views

What's the distribution curve for meteor sightings?

I know that meteor showers have a "peak" observation time. What does the distribution in time look like? Is one side of the peak steeper/shallower or longer/shorter than the other side, and if so, ...
3
votes
0answers
22 views

Why is the E-mode polarization spectrum out of phase with the Temperature spectrum?

The E-mode polarization power spectrum of the Cosmic Microwave Background displays the same acoustic peaks that can be seen in the (more famed) temperature power spectrum. However, they are out of ...
1
vote
1answer
27 views

attractors of Mercury's spin-orbit relation

Mercury rotates at such a rate that the Sun appears to stand nearly still at perihelion, when the tide is strongest. Is there a mechanism that tends to adjust the orbital eccentricity to improve the ...
0
votes
1answer
109 views

If earth were the size of a marble would it be smoother than a marble? [closed]

As the title states, If earth were the size of a marble would it be smoother than a marble?
2
votes
1answer
85 views

If oxygen were pumped into space where would it go?

If an astronaut went into space with a sealed container of oxygen and opened it up in space and let all the oxygen go, what would happen to it? would it all just dissipate into some other particle or ...
4
votes
2answers
167 views

Why do objects all orbit in the same direction?

In a solar system or a planet that has many moons, why do their orbiting objects all orbit in the same direction? Is it possible for two orbiting masses to orbit in the opposite direction of each ...
3
votes
1answer
113 views

How did the moon's orbit become eccentric?

The Moon's orbit is more eccentric, 0.0549, than most planets. I can understand that planets get eccentric by disturbing each other like under the late heavy bombardment. And likewise for multiple ...
6
votes
2answers
181 views

Are those noise or stars?

So there is this huge picture by Hubble. Better yet, with the zoom tool And if you zoom to the maximum level, you can see a seemingly uniformly distributed dots of orange and blue. Are those ...
1
vote
1answer
38 views

How could eclipse happen on the same day in a different calendar? (45 AD)

According to the eclipse calculator I use (Alcyone), a partial eclipse 0.314 magnitude occurred August 1, 45 A.D. in Rome starting at 8:35am local time. This would seem to correspond to an eclipse ...
1
vote
1answer
72 views

Is there some upper limit in the moon size distribution?

The planets range hugely in sizes, Jupiter is more than 300 times as massive as Earth. But the sizes of the large moons seem to be uncorrelated with the sizes of the planets they orbit. Why doesn't ...
-1
votes
2answers
92 views

Southern hemisphere is short of radio telescopes? [closed]

In northern hemisphere, we have GBT, Arecibo, Parkes, Jodrell and VLA, while in southern hemisphere, only Australia has big radio telescopes. ALMA is in Chile, but it is in submm. It is not ...
6
votes
2answers
243 views

How can we be 13.2 billion light years from another galaxy?

How did we get 13.2 billion light years from the faraway galaxies being discovered with Hubble? If we all started near each other at the Big Bang, and we all travelled slower than the speed of light, ...
3
votes
2answers
98 views

The universe is dying vs the universe is ever expanding

How does the idea that the universe is dying (trumpeted as some big new revelation the past few days on several new sites I keep seeing pop up on google news) square with the idea that the universe is ...
2
votes
1answer
62 views

Configuration required to tidally heat Earth-like rogue planet

Could it be possible for Earth-like rogue planet to maintain large bodies of liquid water on the surface without a sun by relying mostly on tidal forces of a moon (or multiple moons). How big/far/fast ...
2
votes
1answer
108 views

Is it possible to have a part of space devoid of matter?

I have recently read this article and I am finding it a little hard to believe that there would be a place that is without matter. So, if there is a galaxy at the other side of the void, we would be ...
4
votes
3answers
201 views

Are there heavenly bodies between galaxies?

I do understand that galaxies were formed in the famous Big Bang. However, I also understand that if such an explosion occurs in empty space it will never form distinct galaxies, it should more or ...
2
votes
3answers
95 views

How do we know that other planetary systems aren't composed of antimatter? [duplicate]

How do we know that other planetary systems aren't composed of antimatter? If they never touch matter, then they don't annihilate. All their observable physics (spectra) are the same as matter, right? ...
0
votes
1answer
87 views

Help plotting a trip to the Moon! [closed]

Take me to the moon! I know this is literally rocket science but, I would like any sources or formulas that would help me plot a trip to the Moon. I'm not sending anything, nor do I ever plan to, I ...
2
votes
1answer
130 views

What particles does a black hole emit when it evaporates itself?

Due to Hawking Radiation, after a very long time, a black hole will eventually disappear. But where does this "evaporation" go? What is this made of?
9
votes
2answers
3k views

What are the differences between matter, dark matter and antimatter?

I thought dark and anti matter were kinda the same, but after saw a video, they mention that dark matter is not antimatter but their explanation is a little fast so I got doubts. What are the ...
1
vote
1answer
387 views

Earth Rotation and Orbit Geometry

Let Line A be the projection of the axis of Earth's rotation onto the plane of the eliptic. Let Line B the line connecting the center of the Earth and center of the Sun. At what times during the ...
1
vote
1answer
56 views

Calculate Atmospheric Extinction Using Source Altitude Angle

I am trying to code up the following article http://dl.acm.org/citation.cfm?id=2349512 (alternative free access version) to calculate the light reflected from the moon to a given point on earth at a ...
3
votes
2answers
298 views

Is the ratio between earth's distance from the sun and the speed of light just a coincidence?

I was doing some calculations to see how hard it would be to observe the speed of light and discovered an interesting correlation between the speed of light and the average distance from the earth to ...
3
votes
1answer
153 views

How much illumination do the background stars provide?

I'm trying to get a better understanding of what things look like in "outer space." The main problem I'm trying to solve right now, is how much illumination is provided by the background stars. Is it ...
4
votes
2answers
115 views

Why are so many sun-like stars found in multiple systems? How do planets form in such a situation?

It has been reported that perhaps half of nearby sun-like stars are found in multiple systems. Why is this so common, and how do planets form in such a situation? Kaitlin M. Kratter, “Sibling ...
7
votes
1answer
73 views

Has New Horizon's data updated Charon's orbital elements?

For years I've been fascinated with the mutually tide-locked bodies Pluto and Charon. In July 2012, The Astronomical Journal published an article The Orbit of Charon Is Circular by Buie, Tholen and ...
1
vote
0answers
47 views

Why would it matter to us if space is infinite versus being finite? [closed]

More specificlly, what are some of the differences for contemporary sciences and humanity if there are multiple universes versus just one? I ask because I'm writing a story and I want to put into ...
1
vote
1answer
59 views

What's the difference between the Julian and the Julian Ephemeris Day?

I'm making a code where I calculate the sun position in a given time. But I also want to learn astronomy with it. I'm following a .pdf to make the program, and in this .pdf it says The Julian Day ...
1
vote
0answers
24 views

What is the term for the point between a star and planet where a 3rd object will cast the largest shadow on the planet?

Is there a particular orbital configuration that would allow an object to orbit a planet while casting a stable shadow on a planet in said position? I would also be interested to know if there is a ...
4
votes
3answers
175 views

What types of signals is SETI (and other such efforts) looking for?

This seemed to be the closest group for this question. Every few months there are a few articles asking "Are we alone in the universe" which focus on the Fermi Paradox, the Drake Equation, and end by ...
4
votes
2answers
370 views

Do all planets have a van Allen radiation belt?

Earth has the van Allen radiation belts. Which other planets have one? Can it be determined if distant planets in other solar systems have one?

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