All Questions

The Pleiades are 450 light years away. Thus when we see the twinkle in the night sky the light that hits our retina emanates from the year 1569 or so. On that proviso; how can we be sure that the star ...

In 2012, the discovery paper for the multiplanet circumbinary system Kepler-47 mentioned a potential third transiting planet in the system: A 0.2% deep transit-like event is present at time 2,455,...

As I understand it, our solar system travels through the milky way with the orbital plane tilted about 60 degrees so that we are sort of traveling in the direction of earth's north. My question is if ...

I read that, if the moon would not be there or if it would dissapear or be destroyed it could cause the earth to rotate into a possible axis of 45° degrees. Because it would be missing the ...

I can't read the Nature Astronomy article A kilometre-sized Kuiper belt object discovered by stellar occultation using amateur telescopes because the library I use doesn't subscribe electronically. ...

Is it possible for there to be a dense enough nebula to form stars outside of any galaxy? Does a galaxy have a minimum size to produce stars? Or could you have a few dozen stars clustered together by ...

What are the evidences to prove big bang theory and proof how the universe began in a hot, dense state 13.8 billion years ago?

I'm wondering about Mars and Titan. If Mars is larger than Titan how come it lost most of its atmosphere? Mars also has a magnetic field while Titan doesn't. Yet Titans atmospheric pressure on the ...

I have an interest in cosmology, but I would no way consider myself an expert. It would be great if the more knowledgeable contributors would be able to answer the question I have posed. The intense ...

Is it theoretically possible for a moon to orbit a planet (let us say Earth size, mass and solar distance) in such a way as to create a planet-wide solar eclipse lasting several weeks? These are my ...

Planets like Saturn & Jupiter are called "gas giants"--does that mean that there is no surface to walk upon? Though some source of gravity is required to hold the gas in place, isn't it? Venus: we ...

I have been wondering for a while now about a scenario of where if you combined Venus & Mercury would it be habitable if located in the goldy locks zone? I have found in my little research that ...

In this answer I estimated that if a DSLR (digital SLR) camera with an aperture of 40 mm were pointed at a satellite in geostationary orbit with a visual brightness of about +11 magnitude, it would ...

I was trying to help my son with a project and thought it shouldn't be hard but turned out I'm not as smart as I thought I was. His project is about celestial navigation. The first step is, given the ...

What’s the closest earth like planet or moon to earth we have discovered in our galaxy?

I'm just curious about that the existence of non-rotating stars. Is it physically possible for a star not to rotate at all? Does magnetic braking eventually stop the stellar rotation?

Answers to and comments on How to drink water on Mars? suggest that one would not want to drink melted water ice obtained from exposed surface deposits near the poles because it may contain various ...

Does water on Mars form from the atmosphere as ice free from salt? Does water desalinize through the evaporation and transpiration? When the fresh top ice is placed in a container then pressurized to ...

I came across post in quora where somebody said that "most astronomers no longer think Planet 9 exists" and being somewhat shocked by that, I did a google search and found a fairly recent article that ...

I'm measuring equivalent widths of absorption lines using a spectrum of a star. I make two or three measurements of each line by making reasonable gaussian fits of the line with IRAF's splot tool. ...

Constellations are dominant features of night sky. But these are basically group of stars that forms particular shapes when viewed from Earth. How much the shape of a constellation will change if we ...

There is no edge to the atmosphere, and therefor I expect there would be a gradual reduction of concentrations of bacteria as we ascend into space. Logically anaerobic bacteria should be able to ...

I am teaching myself astronomy and I'm working on a basic problem regarding time dilation around black holes. The question is basically this: if a neutron were ejected from a nucleus at a distance of ...

If the whole observable Universe is as big as planet Earth, how big would Earth be?

In Star Wars, the planet Naboo has a plasma core, instead of a molten one. Can a planet really have a plasma core?

If the Milky Way galaxy is as big as planet earth, how big is Earth?

Will Earth at some point stop rotating anti-clockwise, stay still, and then rotate clockwise?

@antlersoft's answer describes some of the challenges to seeing any details in the small disk of Mars in small amateur telescopes. In the case of reflecting telescopes, it mentions the use of either ...

The Daily Galaxy article “The Lost Hubble” –New! Deepest Image of the Universe Ever Taken says: To produce the image a group of researchers from the Instituto de Astrofísica de Canarias (IAC) led ...

How can gravitational lensing makes a quasar brighter than it would in the absence of a foreground galaxy?

The drawing below, found in Wikimedia and at lib.harvard.edu is of a very long tubed aerial telescope. I believe it is taken from his 1673 work Machinae coelestis. I've always wondered about the ...

I have read that it takes billions of years for stars of approximately the size of the Sun to get through the main sequence, after which it will enter the red giant phase. When that happens, how long ...

There are several different classifications of gravitational lensing phenomenon. Here I am asking for any examples of strong lensing where the lensed image of an extended object is magnified and ...

Wikipedia gives the following physical dimensions for the Moon: Physical characteristics ...

I have long considered astronomical observing as a form of remote sensing, though quite different than typical remote sensing in that many objects observed are not resolved. I am wondering, though, ...

Edit: Geometric answer from Math.stackexchange I am trying to understand where the circumpolar equation comes from. $\delta \geq \frac{\pi}{2} - l$ I can understand that the sort of "rotation" of ...

A search of the Internet is so clouded with discussions about the asteroid belt or asteroids orbiting the planet Earth that I couldn't see an answer to my question. Do we know if there are asteroids ...

As far as I am aware, the latest spectral types that have been assigned are around Y2, for objects like WISE 0855-0714 that have temperatures around 250 K or so. I've also seen several directly-imaged ...

A photon is travelling through space. As it travels, the space through which it travels is expanding Does this describe A - a photon travelling from a distant galaxy to earth B - a photon travelling ...

Hi I have two Galileo 700mm x 60mm Astro/Terrestrial Refractor Telescopes. Can I take the lenses out and make one powerful telescope?

I'm working on a program that generates the basics stats of a terrestrial planets in binary star systems. I'm not the best at this kind of math, so I'm having trouble calculating the planetary ...

This is more a terminology question, since Mercury and Venus certainly "move backwards" in the sky. The question is whether we call this retrograde motion. I'm referring to apparent retrograde motion ...

I have been reading some literature on using the HST to take spectra of exoplanet atmospheres when exoplanets transit in front of their stars. The literature mention two modes of observations, '...

I'm trying to simulate Earth's orbit using 2nd Newton's Law and cartesian coordinates. The program seems ok, but when plotting graph, it's a parabola. I know the shape of orbit changes according ...

I'm using IRAF's splot command to view spectra from stars. I can zoom into a segment by pressing a key on its right and left edges. I can also use z key to zoom in ...

I dont know astronomy, but I am preparing for the second stage of IJSO, and here in India they do add some questions like these ones. ...

I am having a lot of trouble getting a sharp image in my telescope. It is a skywatcher with a focal length of 1200mm and a diameter of 254mm. I have a laser colimater that I got for Christmas, so I ...

When is Earth closest to the Sun? Well, you say, perihelion of course. But perihelion is when the Earth-Moon barycentre is closest to the Sun. Not Earth itself. The barycentre is on average 4,671 ...

We all know that our sun will become a red giant in a couple of billion years? But how fast will the process be when it starts? Would it be theoretically possible (disregarding the deadly effects of ...

Shooting stars are actually meteors falling down on the surface of earth. How come some of them appear shooting up and not down?