0
votes
0answers
1 views

Listing calculation steps from Two-Line Element to azimuth and elevation angles

I want to visualize the calculation chain from a Two-Line Element (TLE) of a satellite to the azimuth and elevation angles of a local observer. I don't want to list the exact formulars. I want to know ...
1
vote
1answer
8 views

How tall are the “fractured” linear structures on Europa's surface?

What are the altitude differences in the high resolution part of this image of Europa? How high do those ridges rise over their neighboring valleys? And how large is the area shown in this image? And ...
1
vote
1answer
16 views

speed of light measurement

While searching for different methods of speed of light measurement, i came across one of the method of fizeau discussed below which i cannot fully understand. In short,in Fizeau’s apparatus, a beam ...
2
votes
1answer
30 views

How does this strategy for chasing the sunset work?

In Randall Munroe's What If? blog he tackles this question: What is the longest possible sunset you can experience while driving, assuming we are obeying the speed limit and driving on paved ...
1
vote
2answers
53 views

Why does the face of the moon 'sync' with the earth? [duplicate]

We never see the dark side of the moon. It rotates so that the same side always faces us. I heard two (dinner party) theories on this: 1. The moon was made by smashing out a chunk of the earth, and ...
1
vote
0answers
15 views

What range of exit pupils work for observing the full moon?

I'm observing the full moon, from a major city, with heavy light pollution and dust. The objective size is fixed, for this comparison, something between 4 and 6 inches. The question is about the ...
2
votes
1answer
21 views

How is the maximum density in a circumstellar disk determined?

I'm working with some equations to model the evolution of a circumstellar disk. One of the equations is $$\rho(r)=Ce^{-\frac{(r-r_{peak})^2}{2 \sigma ^2}}$$ where $\rho$ is density, $r$ is the ...
1
vote
2answers
70 views

What is a low mass Black Hole?

Is a Low Mass Black Hole also called a Stellar Mass Black Hole? Can Low Mass BH be also called Primordial BH? (If low mass BH are Stellar Mass BH-What is their size in terms of the mass of the sun?)
2
votes
1answer
32 views

Effect of the absence of atmospheric refraction to sun rise and sunset times

What is the effect of absence of atmospheric refraction on sin rise and sunset time? Is it will be delayed or earlier for sunrise and sunset, and why? Thank you:)
1
vote
2answers
42 views

can we see all binary stars as pairs?

As it is obvious from the question title is there any restriction or cases that we can see the binary stars as not in pairs also is there any binary stars doesn't linked together by gravity ? I ...
1
vote
1answer
30 views

Roche Limit for Earth-like body around Earth-like body

In a discussion elsewhere about binary planets, it came the question. How near can a planet like Earth (maybe Earth itself) be to another planet like Earth before both of them tearing apart due to ...
2
votes
1answer
91 views

moonless night and lunar phase

How to define moonless night? There is no moon at all during some night? How to calculate and know whether the moon would appear during one night? If the lunar phase is full moon, is it possible ...
1
vote
0answers
22 views

stellar evolution fortran code-runge kutta mass step from center to fitting point

I am trying to integrate the four stellar model equations from the core to a fitting point and from the surface to the fitting point (xf).When I start the outward integration however i have to use a ...
-2
votes
1answer
38 views

Determining Distances in Space

I suspect the scope of this question may be to broad, but: what are some methods for determining distances between two objects in Space? Please present the methods in historical order, so as to make ...
1
vote
1answer
34 views

Astronomy Olympiad Books

I'd like to one day take the Astronomy Olympiad, however I'm at a loss to know where to begin. As it currently stands I have no experience whatsoever with Astronomy. If there are people here with some ...
1
vote
2answers
43 views

Why does a particle feel no force at radii greater than itself?

I am working through Liddle's "An Introduction to Modern Cosmology", and in a newtonian derivation of the Friedman equation he states: in a spherically symmetric distribution of matter, a particle ...
1
vote
1answer
31 views

Yellow object between δ Ori and η Ori

Can someone perhaps assist me in identifying the yellow object between δ Ori and η Ori? I took an image of this object, but I can't identify it. It can be seen on the image below, hosted on the Eagle ...
-2
votes
1answer
47 views

Why does Earth enjoy a significantly longer time as a habitable planet as compared to Mars or Venus?

On a related note, why didn't Venus remain habitable for longer than it did? Is the current hypothesis as to the time when Venus's atmosphere became hostile and what event triggered it, proven true?
5
votes
2answers
50 views

How do you calculate the effects of precession on elliptical orbits?

Kepler's first law states that planets (and all celestial bodies orbiting another body) travel in elliptical orbits, which have well-known formulas that make it relatively easy to calculate the ...
1
vote
1answer
24 views

How to determine what the unseen object is if a white dwarf is orbiting it?

Imagine you observe a 1M white dwarf orbiting an unseen object with P = 0.02 years and a a = 0.2AU. What is the unseen object? Why? (your explanation should include a calculation)
1
vote
1answer
20 views

How to find Schwarzchild radius and and parsec help?

I don't understand how to do this problem. I have been stuck on it for an hour! The supermassive black hole at the center of the Milky Way is about $4 ×10^6 \text{ M}$ in mass. What is its ...
2
votes
1answer
30 views

Is axial tilt direction correlated with semi-major axis direction?

Earth comes closest to the Sun every year around January 3. Winter solstice is at 21-22 December, merely some 12-13 days away. That means projection of Earth rotation axis onto the plane of its ...
-2
votes
1answer
41 views

As of now did a radio telescope ever recorded something else than the silence of space? [closed]

When a radio telescope listen to the Universe; a constant sound is recorded. Is it the noise "of the mic" : interferences? Scientists says that when they will notice variations on this basic constant ...
2
votes
2answers
78 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 ...
0
votes
1answer
55 views

Humans surviving in space [on hold]

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 ...
5
votes
2answers
72 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? ...
4
votes
2answers
280 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 ...
2
votes
0answers
20 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
0answers
30 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
0answers
29 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
1answer
78 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
57 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
75 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?
9
votes
1answer
112 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
vote
2answers
32 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 ...
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 ...
3
votes
4answers
165 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" ...
5
votes
1answer
63 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
60 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?
-1
votes
0answers
23 views

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

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
420 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 ?
1
vote
2answers
39 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 ...
12
votes
3answers
94 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
89 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
49 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
139 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
76 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
97 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
91 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 ...
2
votes
0answers
28 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 ...

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