Astronomy Stack Exchange
Astronomy Stack Exchange

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1500 questions
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What was the length of year 1 million years back?

We know that the universe is gradually expanding and this indirectly means that the gravitational force between sun, earth, planets and other stars (roughly anything in the universe) is gradually decreasing as gravitational force is indirectly…
SpringLearner
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Timeline of falling into a blackhole

For some "average sized" black hole, how long would it take for a distant (spacesuit-wearing!) astronaut to: be able to see the gravitational lensing with the naked eye clearly feel the gravity gradient reach a lethal gravity gradient cross the…
aaaidan
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What visual artifacts are expected from the JWST?

What visual artifacts should we expect from the images that will be released from the James Webb Space Telescope? Specifically, do we expect 3-pronged diffraction spikes (any preview how they would look?)? Do we expect any artifacts due to the…
Oak
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Could an impact have resurfaced Venus 300 million years ago?

Venus surface isn't older than about 300 million years. The only explanation I've come across is that some kind of global volcanism resurfaced the planet. But couldn't it have been an impact event? A huge comet hitting it by chance, maybe making…
LocalFluff
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Perceiving movement of stars

Are there any stars visible to the naked eye whose position, over a normal human lifetime, can be seen to have changed (relative to other stars in the vicinity)?
Paul Ho
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Astrophotography - Unable to achieve focus with current setup

I am new to astrophotography and am looking for guidance. I have the following equipment: Orion StarBlast 9814 4.5" Altazimuth Reflector Tabletop telescope 1.25in Telescope Adapter Extension Tube T Ring for Canon DSLR SLR Camera DC618 17mm and 6mm…
Nick
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How is a non-rotating black hole created

How are non-rotating black holes formed? I guess that non-rotating black holes are formed from non-rotating stars but I couldn't find any proof that such a star exists on the internet. If this is true can you also put up an example of such a…
CipherBot
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Are there any Stars we know don't have planets?

We have been looking for planets around other stars for a while (see related https://space.stackexchange.com/questions/1484 ) and we are finding lots of planets, some of them are Earth like According to an the answer at…
James Jenkins
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why does pluto have a high orbital inclination

Pluto has a high orbital inclination compared to the planets in our solar system. What has caused Pluto to have such a different orbit -- was it always like this, or did something happen to make it so?
Tara
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How did our ancestors discover the Solar System?

I wonder, how did our ancestors discover the Solar System? They did not have any telescopes to see distant objects, right? Even a planet looks like a star from a distance. They discovered the rotations of different planets without having much…
user804401
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Is there a limit to how hot a star can be?

I think that size and mass do not correlate to temperature, but then again these factors contribute to the internal pressure. I would like to know if there is a limit to how hot a star can get and what mechanism(s) could drive a star to get…
user6760
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Could the James Webb Space Telescope detect biosignals on exoplanets?

The James Webb Space Telescope (JWST) which is slated to launch in 2018 will bring us a better view of exoplanets, but will it be sufficient to detect signs of life on at least some of those worlds? A good answer will provide an estimate of the…
called2voyage
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Is there a pattern between the mass of a body and the mass of orbiting objects around it?

I was looking at Wikipedia's Solar system page, and it says that Sun represents 99.86% of the whole solar system mass. I found that pretty huge. So i calculated ratio of masses : Earth / (Earth + Moon) and it's about 98.78%. I did the same with…
Thibault
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Sunsets: Mars/Earth

I understand why our sky is blue and turns red when the sun sets or rises. I know why the sky on mars is red, but why does it turn blue during sunsets and rises? Shouldn't this actually not work due to the shorter wavelenght blue has compared to…
Astrony
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When the universe expands does it create new space, matter, or something else?

I am wondering what exactly is meant when it is said the universe expands. Does it simply create new space for matter to fill, does it also create new matter/dark matter to fill that space, or am I way off? Thank you for any help!
Joey Seibel
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