# All Questions

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### Is Earth's 1g solid surface gravity unusually high for exoplanets?

The surface gravities of the Sun’s planets are all close to 1g, 0.38-2.53 (about a factor of e, by chance). The cloud-top gravity of the gas giants is not too interesting here, but I suppose that the ...
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### Is the universe expanding faster than speed of light?

The celestial bodies like stars and galaxies are moving away from each other. How fast are they moving apart? Is that speed more than the speed of light?
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### How long until we cannot see any stars from other galaxies?

Since all the galaxies are moving further away from each other at a faster and faster rate, eventually we won't be able to see stars from other galaxies. How long until we can't see stars from other ...
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### Is it possible to be 'still' in space?

So I was reading this answer about how galaxies are the fastest moving objects in the universe because space is expanding faster than the speed of light. This got me wondering, would it be possible to ...
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### What is the evidence that twentieth century climate change is human-induced rather than a part of natural Milankovitch cycles? [on hold]

After seeing this graph on a Wikipedia page, where it can be seen that current carbon-dioxide concentration is not very remarkable on the large scale, I realized that I don't know what is this strong ...
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### What is the orientation of planetary orbits?

I'm working on a planetary motion simulator. I've been working through the equations anomaly, eccentricity, etc. The one thing I'm curious about is if all the ellipses are oriented the exact same way ...
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### Why can't I see Mars clearly?

I just bought my first telescope - a Celestron CDC 1100. It came with a 40mm lens so with a primary focal length of 2800mm the power should be 70x. My problem is that I've looked at Sirius and Mars ...
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### Was the Milky Way ever a quasar?

Is there any evidence that the Milky Way could have been a quasar in it's early history? Is it thought that most galaxies come from quasars?
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### Convert orbital elements to positions and velocities

I've written a quick and dirty n-body simulator, but currently it requires initial positions and velocities. I've been looking for a way to convert Keplerian orbital elements to positions and ...
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### How do I calculate the velocity dispersion of a galaxy given an integral field spectrograph?

I couldn't find on the web how to get the velocity dispersion and velocity maps of galaxies from the 3D data cube that I get from the integral field spectrograph.
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### Gravity Assist - Orbiting Satellites & Speed Increases [migrated]

So, a gravity assist in very simple terms is when an object uses a planet's gravity and rotating momentum to increase the objects speed. If this is true, why doesn't the ISS get further and further ...
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### What will happen to life on Earth when Andromeda and Milky Way galaxies collide?

It is said that, Andromeda and Milky way galaxies are coming close to each other with the speed of approx 400000 km/hours. They will be together in the next 4 billion years. 1> What will happen to ...
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### Is it possible to create an artificial Black Hole?

I am quite curious about black holes. Once I just thought whether it is possible to create an artificial Black Hole, i.e. an human made black hole. Also explain there formation if it is possible.
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### When will astronomers “run out of” things to discover? [on hold]

I have always wondered when astronomers reach the point that they cannot discover anything. Modern astronomy has been there for a while, but when will we know everything about the universe?
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### How many planetary systems exist in our galaxy?

For many years scientists have studied our own solar system and modern technology allows them to look deeper and deeper into space. Knowing the Sun is only one of a few billion stars in the Milky Way ...
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### What is the speed of light relative to (in space)?

From what I understand the universe is expanding faster than the speed of light and accelerating so that it's possible that a given galaxy: $A$ will no longer be visible to another given galaxy: $B$. ...
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### Do solstices and equinoxes shift over time?

Right now, I think the winter solstice is around December 21. Has it always been around this date constantly? Since the earth's axis's 23.45° tilt will be on the exact opposite side in 13000 years ...
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### Spotting international space station

Recently, I visited the NASA website which provides sighting locations to see the international space station. As we all know, we can even see ISS with bare eyes in clear sky like passing star without ...
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### Nuclear fusion or fission may be the future of space exploration! [migrated]

Today while studying about Nuclear Reactions, I found that we can produce a large amount of energy. So, why not we introduce this energy in our Space Exploration Rockets. It may decrease the time of ...
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### star atlas with absolute magnitude and spectral type

Is there any star atlas someone recommends? Then for some kind of star with a definite spectral type, we can know its absolute magnitude.
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### Earth's gravitational pull on ISS

How do they make International space station to orbit the earth beyond earth's gravity acting on it? We all know that ISS is rotating at an altitude of just 350km away.How could ISS escape earth's ...
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### The reason behind Big Bang

It always amuse us to research about things around us and we always start our research with a question that - what must be the reason for happening of that phenomenon? As we know that the formation ...
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### Is it possible to extend the life of a star?

Is it true that when a star 'runs out' of its fuel, it hasn't really used up all its hydrogen, it still has hydrogen left, but the hydrogen is not at its center where the fusion happens. If something ...
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### Question about the formation of elements

So, elements such as iron, gold, etc. are formed from different types of supernovas, whether it's type 1A or 2. My question is, is it possible that there are elements that are formed that we never ...
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### Average rate of supernova x number of stars

If we would take the average number of supernovae per year and multiply that by the number of stars, could we figure out how many years it will be before all stars are gone?
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### Apogalacticon and Perigalacticon

What is the length of the apogalacticon and perigalacticon of the Sun and Milky Way? The general terms seem to be apoapsis and periapsis. My greatest efforts at Googling have failed miserably. If ...
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### Why is a meteorite impact on the moon visible as white light?

You can watch a video of a meteorite impacting the moon at the npr.org website. Why does the impact produce white light? I understand that the impact is like an explosion, but there is no air on ...
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### State of the stars

This question may sound silly but I'm really not pretty sure whether the stars are rotating or stationary.If they are not rotating what makes them to be stable?
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### Do more objects appear on sky in time?

I would assume that, with light from more distant areas in space reaching the earth, we should be able to see more distant (and older) objects. However there's lot of weird stuff regarding the space ...
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### Do telescopes harm while observing sun through them?

I don't know whether we can observe a sun through a telescope. But if we can then will it harm our eyes and if such telescopes exists what is their configuration?
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### Sattelite's orbit

What is the maximum distance for a satellite to orbit the earth? Does earth's gravity has the impact on satellite? I do know that earth's gravity will never be zero and it's gravity is inversely ...
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### When did the Moon stop?

According to various theories the Moon was created around 4.5 billion years ago. About all of these theories suggest that it was rotating around its axis at that time though. Currently, Moon is at ...
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### Asteroids turning out to be Meteorites [closed]

What causes an asteroid to loose control over it's orbit and enter in to another objects atmosphere?
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### SLR for Astronomy [closed]

I know that companies like Canon make special version of their digital SLRs for astro-photography but keeping track of them all is not easy. I'm looking for a quick answer on what are the top couple ...
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### 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?
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### Locate asteroid in asteroid belt

I was interested in tracking the orbit of 1986 DA. I couldn't find any resource when I looked. Just for fun, so any help appreciated.
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### How fast is the universe expanding?

I've hear several theories stating that the universe is expanding faster than the speed of light, others claim that the universe expands faster the further away you measure it. Which of this is ...
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### Do meteorites streak across the sky in the same direction?

Once while camping with my family as a child we all watched a meteor shower in the summer (in the month of August). All the meteorites streaked across the sky in the same direction. Obviously, this ...
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### Can an amateur astronomer bounce a laser off the moon?

In the TV show "Big Bang Theory" episode "The Lunar Excitation", the gang fires a laser from their rooftop, bounces it off mirrors on the moon, and measures the laser coming back on a computer. Is ...
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### Why is the interstellar medium so hot?

On this link, it states the following: "large assemblies of galaxies that are permeated by even larger amounts of diffuse gas. With temperatures of 10 million degrees or more". How are these ...
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### From which country or area is the new moon visible first?

Being able to see the Moon is dependant on various factors like sunset timing etc. Considering all these factors, which country or area of the world sees the new moon first? I am asking about the new ...
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### Do planetary surface temperatures change in unison in a solar system?

Are there any known correlations between the changes in planetary surface temperatures in a solar system? If so, do the farthest planets have smaller albeit correlated changes?
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### What is Event Horizon of a Black Hole?

The boundary of a black hole is said to be surrounded by event horizon - the point of no return! What is its significance in terms of general relativity?
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### How to get the longitude/latitude from solar zenith/azimuth?

How do I get the longitude/latitude from zenith/azimuth? Or how can I position my sun in a 3d application? code extracted from here ...
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### How close would quasars have been to each other?

My understanding is that quasars are the early phase of formation of galaxies. At the time quasars were forming, the universe would have been smaller and therefore things closer to each other. About ...
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### Age of the universe

A Galactic year is estimated to be around 250 million "terrestrial" years. That means there will be about 4 rotations per billion years. And age of the universe is estimated to be near 13.8 billion ...
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### How far apart can two people watch the moon simultaneously?

Obviously there's a limited part of earths surface where the moon is visible at any given time. I imagine the area of this surface would be a lot smaller than the area where the sun is visible at any ...
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### How can I calculate the orbital periods in a binary star system?

I have two stars, with known masses and known orbital radius. How do I calculate the orbital periods of both stars?