4
votes
2answers
887 views

Will Earth lose the Moon before the Sun goes into supernova?

Ive read on some sites and saw on youtube videos that the moon is getting away from earth by 1-3 cm a year. Is this enough to make the Earth lose the Moon before the Sun goes into Supernova? Im ...
3
votes
1answer
48 views

Are there many faint meteors that are too faint to see with the naked eye?

I remember one time a while back looking at the night sky through night vision goggles. One interesting thing I noticed is that there appeared to be many very faint meteors in the sky practically all ...
3
votes
1answer
51 views

Leonid meteor showers and the Tempel-Tuttle comet

I've been reading about the Leonid meteor showers and am struggling to understand one piece of information. On Wikipedia (Tempel-Tuttle), it states: The orbit of 55P/Tempel–Tuttle intersects that ...
1
vote
1answer
121 views

What are the azimuths of the planets' orbits?

I am creating a virtual solar system model and I want it to be as realistic as possible (e.g. orbits are ellipses, not circles, and orbits are oriented correctly, not all coplanar). In order for me ...
-1
votes
1answer
114 views

How can there be anything “beyond” the CMB?

Two things we take, for this purpose, to be axiomatic: The CMB is the oldest thing we can observe directly The cosmological red shift tells us how "old" something we are observing is Yet we also ...
3
votes
1answer
70 views

Is broadcasting the location of Earth to potential extraterrestial civilization regulated?

How many times have we broadcast the location of Earth to the outer space? Are there any regulation in doing so? I know so far we have send the Arecibo Message, and any receiver can trace the message ...
1
vote
3answers
107 views

Does the Moon have an aurora?

If the Moon has a magnetic field and can possibly receive solar wind, then does it have an aurora? If Earth has an aurora, and Saturn has an aurora, then could the Moon possibly have an aurora?
11
votes
1answer
173 views

Why Jupiter's Great Red Spot is Reddish?

The Great Red Spot is a persistent anticyclonic storm, 22° south of Jupiter's equator, but why is it reddish? From Wikipedia: It is not known exactly what causes the Great Red Spot's reddish ...
1
vote
2answers
34 views

What are some applicable problems with the correct usage of G?

In some fields of astrophysics, where distances are measured in parsecs (pc), velocities in kilometers per second (km/s) and masses in solar units (), it is useful to express G as approximately 4.302 ...
3
votes
4answers
274 views

Hulse Taylor Binary Pulsar - How is “Cumulative Periastron Time shift” calculated?

Following on from a previous question about the interesting Hulse Taylor Binary Pulsar. BACKGROUD Weisberg & Taylor, 2004 present a graph showing the change in "Cumulative Periastron Time Shift" ...
7
votes
3answers
127 views

What is the long term fate of the gas giants?

If I'm not mistaken, it is believed that the reason for such turbulent weather on the 4 outer gas giant planets is that the internal pressure is so great that it is generating heat, which is causing ...
4
votes
1answer
75 views

Is the dark energy between the moon and Earth measurable in any capacity?

What are the experiments, or measurements, that can detect, or account for, dark energy involved in making calculations concerning Earth and its only natural satellite?
8
votes
2answers
520 views

Why all the photos from 67p are black and white?

I was wondering why every picture we saw on internet about Rosetta's landing on 67p just black and white ? Is there something i should know ?
3
votes
2answers
85 views

Standard practices and models for generating the ephemerides of the solar system

I am familiar with the theory on generating the positions of the members of the solar system, but have been unable to find out the standard practices and methods of professional astronomers in ...
13
votes
3answers
131 views

Why is the Oort cloud presumed to be spherical?

Most descriptions of the Oort cloud depict it as a mostly spherical distribution of planetesimals, with occasional allowance for an inner component that is more donut-shaped. This is slightly at odds ...
2
votes
2answers
120 views

The defintion of star/planetary/solar system

In many science fiction stories, we hear the term star system that mostly refers to a star and its planets. This is often used interchangeably with the term solar system. But after some research I ...
3
votes
1answer
67 views

Hulse-Taylor binary pulsar - what is the rate of mass/energy loss from the source?

Following on from an earlier question about the very interesting Hulse-Taylor binary pulsar. The high-frequency (radio) beam from the spinning pulsar sweeps across Earth about 17 times per second. ...
4
votes
1answer
186 views

From what distance can one object influence gravity of another object?

Each object in the universe has its own gravitational influence on all other objects in the universe. What distance do they have to be from each other to create only one gravitational influence? ...
2
votes
1answer
99 views

Where is the center point for the Supergalactic coordinate system?

Im trying to build a 3D visualization of the Supergalactic coordinate system and couldnt find any reference to where the center point should be (sun, galactic center, earth, etc). Also I already ...
3
votes
3answers
136 views

Strong force and metric expansion

If the expansion of the universe (the metric) continues (and perhaps is accelerating), in a very large but finite time the expansion of the metric will clash with the effects of the strong nuclear ...
4
votes
1answer
132 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 ...
5
votes
1answer
145 views

Given a date obtain latitude and longitude where is the sun zenith

Searching is easy to find terminator line (frontier between day and night) or the position of the sun in the sky given a position on the earth and a time; but I can't find how to obtain where is the ...
1
vote
2answers
96 views

Is a Wormhole a tunnel? [closed]

In films such as Interstellar, 2001: A Space Odyssey, and Contact (and also Star Trek Deep Space Nine) wormholes are depicted as tunnels along the edges of which fantastical colours and shapes lie. ...
2
votes
3answers
176 views

How is the universe bordered?

This answer says that some models describes the universe as finite. How do those models describe the universe's border? Does the border (theoretically) exist? Is it a solid border? Do they predict ...
1
vote
1answer
94 views

Instrumental magnitude to “real” magnitude - Photometry with not enough data?

I have a lot of data taken in R, B, V, Luminance and Halpha-bands which I want to analyse photometrically (one target in the frame). The frames are already reduced (with flats, darks etc.) and have a ...
3
votes
2answers
161 views

What should I look for in an astronomy tripod?

I have a Celstron SkyMaster 20x80 binoculars, and a tripod — Vanguard 263AT with a SBH-100 head. The binoculars weighs 2.2kg, while the head is rated to a loading capacity of 10kg, and the legs to a ...
3
votes
1answer
81 views

Number density of stars on the Galactic plane

The number density of stars (e.g. the number of stars per cubic parsec) is given by $$N(z) = N(0) e^{-|z|/h}$$ where $z$ is the height above the Galactic plane, $h$ is the scale height for a specific ...
1
vote
1answer
120 views

Can General Relativity indicate phase-dependent variations in planetary orbital acceleration?

In a previous question about differences in Newtonian and GTR gravitional force for the case of star-planet gravitational interactions an approximate relationship was noted between the expressions for ...
4
votes
1answer
178 views

At what density does helium burning start in a star?

I have seen several references that say that helium burning begins in a star once the core temperature reaches $10^8$K (such as here) but nowhere that says what density that corresponds to. Does ...
2
votes
1answer
60 views

How many observations does it take to determine the orbit of a TNO

Several observations of a distant solar object must be taken before determining its orbit, but in the case of objects discovered beyond Neptune's orbit, just how many are required over what period of ...
1
vote
0answers
29 views

VSOP for exosatellites? (Io, Titan, Ariel, etc)

VSOP87 (and the subsequent VSOP2000 and VSOP2013) provide reasonably accurate planetary positions while still maintaining a small file size compared to the Chebyshev polynomial files. VSOP ...
3
votes
1answer
102 views

What is the degree of ionization is the solar photosphere?

I am wondering how many free electrons per baryon and how many free electrons per atom there are in the solar photosphere. This number depends on the abundances of the various atoms found in the ...
6
votes
2answers
567 views

How deep and shaped is the depth of a black hole?

A common representation of a black hole is a black circle which if I'm correct, indicates its breadth. This representation depicts it as a 'plate', so a really small depth compared to its breadth. ...
4
votes
1answer
101 views

How bright are the outer planets, when at close range?

Seven probes have passed by or orbited outer planets. I wonder how their photos differ from the naked eye view one would have if one were actually there. Saturn is 10 AU from the Sun, which means ...
7
votes
1answer
162 views

Explanation for the mathematics behind Venus' retrograde motion

I've always been interested by the pattern within Venus' orbit around the sun. I found this image and formula of its retrograde motion in the upper right hand corner which confused me. What does it ...
6
votes
3answers
253 views

Which stars did the Sun form with?

The Sun formed 4.5 billion years ago, in a molecular cloud. I assume that there were other stars in the vicinity (as is common in molecular clouds). Which stars are they? Where are they now? Are they ...
2
votes
1answer
54 views

Could supermassive black holes form in dwarf galaxies?

Supermassive black holes often exist in large galaxies (e.g. the Milky Way, Andromeda). They make up a fair portion of the galaxy's mass. Is it possible for a supermassive black hole to form in a ...
1
vote
0answers
74 views

How do we know the big bang expanded space and not the other way around?

Whenever we hear an explanation about the big bang, it is always phrased in such a way that it was an explosion which used some kind of pressure to expanded the universe out. I wonder, however, would ...
0
votes
3answers
314 views

Why did the big bang not just produce a big black hole?

Questions I've often wondered about: 1) If all the matter and energy were concentrated at a single point at the big bang, why wasn't that a black hole, or why didn't it form one? 2) If the reason #1 ...
2
votes
2answers
208 views

Orbiting supermassive black hole or galactic center of mass?

One of the ways they measure the (supposed?) supermassive black hole at the galactic center of the milky way is to measure those tens of stars right at the galactic center that are orbiting what ...
2
votes
3answers
163 views

What happens if you fail to reach escape velocity for the galaxy?

I was listening to Skeptics Guide to the Universe the other day, and Steve Novella mentioned that the escape velocity for the galaxy is 544 km/s. If an object fails to reach escape velocity on Earth, ...
1
vote
0answers
32 views

Super massive black hole mass estimation in literature

What is the most accurate method for SMBH mass estimation? In the literature I could find 5 methods : (1) Marconi & Hunt 2003, (2) Hu 2008, (3) Gultekin et al. 2009, (4) Graham 2007, (5) McLure ...
1
vote
0answers
36 views

Synthesising types of galaxies using various stellar spectra

I have asked this on Physics Stack Exchange but Astronomy is probably more appropriate. I have been given the task of synthesising an elliptical galaxy, a starburst galaxy and a spiral galaxy ...
5
votes
2answers
135 views

Can a gas giant have an other gas planet as satellite?

Is it possible for a gas giant (A very big one) to have an other smaller gas planet as satellite?
1
vote
2answers
79 views

Is gravity a source of infinite energy at a cosmological scale

As I understand it, gravity cannot be attenuated by any medium (in the way that EM radiation can be, for instance). Does this, then, not make it a source (theoretically, I am not talking of ...
6
votes
1answer
85 views

What is the reason for high lithium concentrations in Sun-like stars?

In reading the European Space Organisation paper Lithium depletion in solar-like stars: no planet connection (Baumann et al. 2010), several conclusions based on their observations include: Lithium ...
3
votes
2answers
198 views

time on earth compared to completely stationary in space

I recently started trying to understand the theory of relativity and I have the following question. Because earth is orbiting the sun at approx 67,000 mph (and its my understanding time slows down ...
-2
votes
1answer
618 views

How many meteors hit the moon every day or in how many days does a new meteor hit the moon?

What is the frequency of meteor strikes on the moon per day?
3
votes
1answer
75 views

Why does Jupiter break comets apart?

I understand that there are magnificent tidal forces that come with getting too close to Jupiter, but what is causing comets like Shoemaker-Levy to get torn apart? I wouldn't expect that the ...
3
votes
1answer
155 views

What would happen if a Black Hole and White Hole Collided?

Given our understanding of both black holes and white holes, what would be the outcome if they were both to suddenly collide? Black Holes: A black hole is a region of spacetime from which gravity ...

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