All Questions

2
votes
1answer
7 views

How do I calculate the positions of objects in orbit?

In a model of the solar system, given the Sun is at the point $(0, 0, 0)$, an given the six orbital elements for each object in orbit ($a$, $\epsilon$, $i$, $\Omega$, $\omega$, $M_0$), how can I ...
1
vote
1answer
25 views

Humans surviving in space

To my (admittedly limited) understanding a human being in outer space wouldn't last very long, mainly due to three factors: the extreme cold the intense radiation and the vacuum of space So if my ...
4
votes
1answer
31 views

How does 67P rotate?

What can be said about 67P/Churyumov-Gerasimenko axial tilt? Is it fixed (if so, at what value), only changing with precession (at what rate?) or does 67P "tumble" with axial tilt changing over time? ...
5
votes
1answer
161 views

Exercise: 2D orbital mechanics simulation (python)

Just a little disclaimer beforehand: I have never studied astronomy or any exact sciences for that matter (not even IT), so I am trying to fill this gap by self-education. Astronomy is one of the ...
11
votes
3answers
549 views

Where does the solar system end?

This is a question I've heard many times in the past, and a quick search of the site says it hasn't been asked here, so I figured I might as well ask (and answer) it. I know that it is rare for ...
3
votes
4answers
103 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. Weisberg & Taylor, 2004 present a graph showing the change in "Cumulative Periastron Time Shift" over a 30 ...
4
votes
2answers
223 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 ...
1
vote
1answer
44 views

Free neutrons and stellar nucleosynthesis

Both the R-process and the S-process of stellar nucleosynthesis rely on absorbing 1 (S) or more (R) neutrons. Where do they come from? I thought there are no free neutrons in stars. (Also the ...
6
votes
0answers
101 views
+50

Detecting Deep Impact

There have been several accounts in media articles of asteroid near misses, many describe that the asteroid was not seen before the near miss. After reading the question and answer to How can we tell ...
1
vote
0answers
10 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
32 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 ...
3
votes
3answers
157 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 ...
1
vote
0answers
19 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 ...
0
votes
0answers
23 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 ...
3
votes
3answers
91 views

Without using absolute magnitudes or isochrones, how might we tell a star's age and evolutionary status?

Usual methods of estimating stellar ages involve isochrone approximations. It can also help to estimate a star's radius by correlating its absolute magnitude with effective temperature and apparent ...
9
votes
1answer
101 views

Why Jupiter's Great Red Spot is Red?

The Great Red Spot (GRS) is a persistent anticyclonic storm, 22° south of Jupiter's equator, but why is it RED? From Wikipedia: It is not known exactly what causes the Great Red Spot's reddish ...
-1
votes
0answers
52 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 ...
2
votes
1answer
47 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 ...
4
votes
0answers
46 views

Can the Philae lander survive one orbit of 67P? [migrated]

The Aphelion of Comet Churyumov–Gerasimenko is about 5.6829 AU. It has a orbital period of 6.44 years. If it stays on the comet for the entire period of its orbit, can it be usable when it is in the ...
4
votes
1answer
121 views

What is the bluest narrow band filter mounted on ground based telescopes?

If we want to check a QSO's lyman alpha narrow band image, could a ground based telescope do that? I mean under the circumstance that its lyman alpha shifts to 3300A.
1
vote
3answers
70 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?
1
vote
2answers
30 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
2answers
39 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 ...
5
votes
2answers
215 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
54 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?
4
votes
1answer
132 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? ...
1
vote
1answer
26 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 ...
5
votes
1answer
57 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 ...
12
votes
3answers
87 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 ...
6
votes
0answers
56 views
+100

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 ...
-1
votes
0answers
22 views

How would you calculate expansion rate of universe in Shanon Entropy? [on hold]

From what I've read, it seems the universe is expanding at 74.3 plus or minus 2.1 kilometers (46.2 plus or minus 1.3 miles) per second per megaparsec. How would you go about converting this expansion ...
8
votes
2answers
388 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 ?
2
votes
1answer
74 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 ...
2
votes
2answers
87 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
3answers
95 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 ...
3
votes
1answer
47 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. ...
3
votes
1answer
79 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 ...
1
vote
2answers
67 views

Is a Wormhole a tunnel? [on hold]

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. ...
5
votes
1answer
37 views

How to compute satellite coordinates (lat,long) given antenna's coordinates, angles and satellite height

Given an Earth station (antenna) coordinates (in lat,long) ant its Elevation (El) and Azimuth (Az), how to compute the satellite coordinates (lat,long), known its height? For simplification purposes, ...
2
votes
3answers
271 views

Why did the moon abruptly change positions in the sky?

Three or four weeks ago I was outside showing my neighbors how cool the moon was through a 'backyard' telescope in broad daylight (~8PM PDT). It was 3/4 of the way across the sky (setting behind the ...
2
votes
0answers
26 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 ...
8
votes
2answers
217 views

If the Wow! signal was not directed at us, then where?

We probably all know the Wow!-Signal, happened on August 15, 1977. Assume that it wasn't meant for us. What was it pointing at then? The signal at that time came from RA= 19h25m31s ± 10s or 19h28m22s ...
3
votes
1answer
80 views

Calculate telescope orientation based on RA, DEC and Lat/Long

I'm parsing FITS files for a project based on data from a telescope. These files include 'DEC', 'RA' and lat long values. I understand roughly the concept of celestial coordinates and I assume that ...
2
votes
3answers
101 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
98 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 ...
3
votes
1answer
32 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 ...
3
votes
2answers
85 views

Assuming a sufficient amount of mass above the density threshold, does the actual concentration of the mass matter in creating a black hole?

I've heard that the actual density of a black hole (within the volume of the event horizon) is pretty low - does that mean that any sufficiently large volume of mass over that density is also a black ...
2
votes
0answers
27 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 ...
5
votes
2answers
717 views

Does the Moon's magnetic field affect Earth's magnetic field?

I wanted to ask a question; it's simple but I cannot find any possible and perfect solution. Earth has poles, North and South. By which we can get directions using a compass or a needle compass, but ...
-3
votes
0answers
23 views

Paper recommendations about the age of the solar system [on hold]

I want somebody to recommend me papers where the age of the solar system is estimated. I don't care about the method employed.

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