Community Digest

Top new questions this week:

Why are there so many binary systems?

Most star systems are binary, but why is that? Why would new stars form close to others, and not (relatively) evenly spread? And even if they are clustered close together, why are the majority binary? ...

orbit binary-star  
asked by RonS 26 votes
answered by Rob Jeffries 30 votes

What are the minimum element requirements for a star?

What elements would be essential for a star to exist? From what I understand our sun is made of mostly hydrogen and helium and most stars have small amounts of heavier elements like carbon, ...

asked by Jake Graham Arnold 11 votes
answered by userLTK 12 votes

Are the orbits of all triple star systems at least technically unstable?

Background: In the Circular Restricted Three Body Problem (CR3BP, CRTBP) some halo orbits are mathematically stable. That means that the orbit of the third body is closed, periodic, and stable ...

orbital-mechanics multiple-star-systems  
asked by uhoh 10 votes
answered by mmeent 10 votes

If a star were travelling at 99% of the speed of light, directly at Earth would we see it?

Stars being flung from black holes in the news made me question if something were heading directly for us at the speed of light, would we even know? Update: Since it's impossible for a star to travel ...

asked by Jake Graham Arnold 7 votes
answered by James K 8 votes

Is Earth's Surface "In orbit"?

I'm having trouble understanding relative angular/tangential speeds at increasing altitudes above Earth's surface. In particular, I find this comparison of tangential velocities on Wikipedia very ...

orbit gravity orbital-mechanics speed radial-velocity  
asked by Rabadash8820 7 votes
answered by Peter Erwin 36 votes

When do radio and tv signals become indistinguishable from background noise of the universe?

I understand the rate an EM signal broadcast uniformly from the Earth will decrease in its power is governed by the inverse square law. How far from Earth will radio and tv signals become ...

radio-astronomy cosmic-microwave-background  
asked by Bob516 6 votes
answered by Keith McClary 3 votes

Will the conditions that allow life to evolve still be around in a trillion years?

Some billions of years ago, systems like the Earth couldn't emerge and therefore life couldn't arise, because not enough of the heavy elements had formed yet. Assuming there'll neither be a big ...

star-formation life astrobiology future  
asked by Valdegg 5 votes
answered by antispinwards 6 votes

Greatest hits from previous weeks:

What is the name of our Solar System?

what is our Solar System called rather than "the Solar System"? I've found "Sol System" and "Monmatia", too, but is there more to it?

solar-system naming  
asked by user7518 12 votes
answered by Peter Erwin 11 votes

If Earth is tilted, why is Polaris always above the same spot?

Why is Polaris, the North Star, always above (or near) the North Pole? If Earth is tilted, Polaris' path should be in winter 23 degrees away from its path in summer, or not?

observational-astronomy earth amateur-observing fundamental-astronomy  
asked by Guest55 46 votes
answered by JohnHoltz 104 votes

Why can't we feel the Earth's revolution?

I googled it and checked a few Q&A and there's only things about "Earth's rotation". But why can't we feel the revolution? They say we can't feel the rotation because the Earth spins at a ...

gravity astrophysics  
asked by dolco 22 votes
answered by Steve Linton 24 votes

Is the moon only 60 pixels?

In doing research on vision, I have learned that "20/20" vision corresponds to a visual acuity of being able to resolve details 1 arcminute in size, that most people have around 20/15 vision, and that ...

the-moon naked-eye angular-resolution  
asked by Phrogz 65 votes
answered by Ilmari Karonen 48 votes

Does the Moon have any oxygen in its atmosphere?

Since the moon has gravity, it's almost impossible that there aren't some gasses trapped on the surface by the moon's gravity. Has any free-floating oxygen been found on the Moon? If so, in what ...

the-moon atmosphere  
asked by Undo 15 votes
answered by GreenMatt 20 votes

What's in the center of a Galaxy?

Ok, so it's supposed that there is a black hole in the center of any galaxy, that makes my head explode because: There is light in the center of the galaxy, but it is supposed that black holes, also ...

star galaxy light  
asked by Antonio Aguilar 9 votes

In my mid-forties, I believe I have seen Pluto for the first time with the naked eye

Early this morning going out on the balcony, I looked up on a star chart app to verify it was Jupiter I was seeing. Then I noticed the alignment of Mars, Saturn, and Pluto on the app. Never being ...

asked by Jason P Sallinger 29 votes
answered by Florin Andrei 99 votes

Can you answer these questions?

Creating a 2D matrix from 2 FITS images of unequal dimensions for Radio/FIR correlation

I have two images of NGC 6946: item description size (pixels) scale (arcseconds/pixel) 1. 70 micron MIPS FITS 241 x 241 4.5 2. 20 cm VLA FITS 512 x ...

radio-astronomy astropy  
asked by user30981 1 vote

Black hole collision animation: What are these extrusions?

In this video uploaded by LIGO Lab Caltech, two inspiraling black holes are depicted. The video's description explains what is shown and can be summarized by: The colored surface is the space of ...

black-hole collision  
asked by BMF 3 votes

How was lunar eclipse proven using the scientific method?

I read a few articles about lunar eclipses and while they explain the science behind them, they do not describe who explained it and how it was explained using the scientific method. Some of them ...

asked by Palash Sharma 1 vote
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