37 votes

Can a magnetic field of an object be stronger than its gravity?

It depends on what object it's acting on. There are many objects, including stars, that have magnetic fields where Lorentz forces on charged particles like electrons and protons are stronger than the ...
Ken G's user avatar
  • 5,320
23 votes
Accepted

What would the night sky look like if the Milky Way were the only galaxy in the universe?

I feel sure this is a repeat, but couldn't immediately find it. The only things in the night sky we can see (with the naked eye) that are not part of our own Galaxy are (on a good night) the Andromeda ...
ProfRob's user avatar
  • 149k
18 votes

What would the night sky look like if the Milky Way were the only galaxy in the universe?

It wouldn't be too apparent, but there are a few objects that you can see in good viewing conditions with the naked eye that would disappear. Here they are in order of brightness. I marked the ...
Pulchritude's user avatar
17 votes
Accepted

Can a magnetic field of an object be stronger than its gravity?

Let's look at the proper magnetic force (as opposed to the Lorentz force on a moving, charged object described in @KenG's answer) on a specimen $S$ of magnetized material with mass $M_S$ as a way to ...
uhoh's user avatar
  • 31.3k
14 votes
Accepted

On what basis is the information about the distance and velocity of the Voyager probes determined?

On what basis is the information about the distance and velocity of the Voyager probes determined? For distance: round-trip travel time of radio signals For velocity: Doppler-shift of round-trip ...
uhoh's user avatar
  • 31.3k
13 votes

What was the length of the solar day 73 million years ago?

There is evidence from Silurian coral fossils that, 430 My ago, there were 420 daily rotations in each annual season, compared to 365 days per year now. If we assume that the year (fixed by mean ...
rob's user avatar
  • 1,021
12 votes
Accepted

How to discover Neptune from the Uranus orbit (by computer simulation)

Here is what I did: Based on their masses, it is safest to initially consider Jupiter and Saturn as well as Uranus. It might also be fruitful to include the Earth in the analysis, to get relative ...
Rody Oldenhuis's user avatar
11 votes
Accepted

Why do we use FITS format for scientific images especially in astronomy? How is it different from formats such as JPEG, PNG etc?

File formats tend to be industry/field-specific, with the format, tools, and expectations of the field coevolving to become more dependent on each other over time. JPEG co-evolved with amateur digital ...
Larry Gritz's user avatar
11 votes

How to know that the 21cm Hydrogen line is the actual emission and not any other redshifted line?

No, not really. The first thing is that we know that ${H}$ is far more abundant than other elements or simple molecules in the universe. The next thing is that the 21 cm line comes from a ...
Carl Witthoft's user avatar
11 votes
Accepted

What liquids can be found in the void space?

No liquid can be completely stable in a vacuum, since all liquids have some non-zero vapour pressure, and so will evaporate at some rate. However some liquids have an exceptionally low vapour pressure,...
James K's user avatar
  • 119k
10 votes

What do the months and hours mean in Tomas Filsinger's Map of The Universe

I am Tomás the guy that designed it following astrocartography traditions. The thing that makes it confusing is that the position of the little suns in the Ecliptic are plotted against the stars at 12 ...
Tomas Filsinger's user avatar
9 votes
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How can I contribute to the scientific community using my telescope?

Amateurs do useful scientific work by being many-handed and widely spread. Many Supernovae are discovered by amateurs. You need a set-up that can image one galaxy after another and look for any "new ...
James K's user avatar
  • 119k
9 votes

Can a magnetic field of an object be stronger than its gravity?

It isn't impossible, but the short answer is "no". A gravitational field will accelerate all matter and energy equally while a magnetic field will only accelerate moving electric charges (other ...
anonymous's user avatar
8 votes
Accepted

Astronomical ABCD...!

Seems a little contrived, essentially you just have to dig deep enough to find a specific enough category that matches the letter. But here you go : K - KBO (Kuiper Belt Object) , if you still don't ...
Michael Watts's user avatar
8 votes
Accepted

What do the months and hours mean in Tomas Filsinger's Map of The Universe

The hours show the lines of right ascension, where right ascension is one of two coordinates used to specify a point on the sky. (The other coordinate is declination, measured in degrees from the ...
JohnHoltz's user avatar
  • 7,952
8 votes
Accepted

Have there been studies of "old photons" to see just how constant things like Planck constant has been?

You can not check if a dimensional constant has changed because you can always reverse that change by a smart change of coordinates (system of units). Despite that, since the current Physics assumes ...
Catarina Alves's user avatar
7 votes

Why didn't Johannes Kepler use data about more planets?

Kepler could, with a lot of work, apply his analysis to other planets of course - but it won't help in proving his point of elliptical path. There are only two planets where this elliptical path could ...
d_e's user avatar
  • 1,667
7 votes

Can some stars not emit any energy in the visible spectrum?

Light that is not light That's meaningless. All light is electromagnetic radiation. A finite part of the infinitely large range of the electromagnetic spectrum is visible light. So you should talk ...
StephenG - Help Ukraine's user avatar
7 votes
Accepted

When black holes forms out of a supernova do they have a very high velocity?

There is no specific answer to this -- anything from "just sits there" to flys away at high speed is possible. It all depends on the symmetry of the supernova (SN) explosion. Extensive modelling ...
Mark Olson's user avatar
  • 7,620
7 votes
Accepted

Why the more-luminous star has larger surface area when two stars have the same temperature?

I'd say your problem is that you are imagining the light rays emanating out from the center of the star. Try it again with light emanating from each square area on the surface, and you will see that ...
Ken G's user avatar
  • 5,320
7 votes
Accepted

Difference between J2000, FK5 and ICRS coordinate systems? Which one does the Yale Bright Star Catalog use?

The questions confuses things: J2000 is the epoch / equinox in which the catalogue is in. This defines the reference point in time for Right Ascension and Declination. See e.g. here https://en....
Christian Herenz's user avatar
6 votes
Accepted

If the universe is 'flat', what shape is it?

Let me clear this up first. Shape of the Universe means the curvature of the Universe. The meaning of "shape" is not the same as in "what is the shape of this object I'm holding". It doesn't mean that ...
Sir Cumference's user avatar
6 votes

The M-theory to understand black holes

Can someone please explain it to me whether the M-theory can be used to explain what is happening in the centre of the black hole where the singularity exists? In Layman astronomy - yes, M-Theory ...
userLTK's user avatar
  • 23.9k
6 votes

How can I contribute to the scientific community using my telescope?

You can also help the study of variable stars and in particular their light curves - You do not require a big scope for this. See for example the American Association of Variable Star Observers, or ...
Dr Chuck's user avatar
  • 4,294
6 votes

Relation between angular resolution and aperture?

The angular resolution only tells you your ability to distinguish ("resolve") two separate points of light. For example, your ability to distinguish the two distinct headlamps on a car from being a ...
zh1's user avatar
  • 161
6 votes

Relation between angular resolution and aperture?

Your formula is correct. In the absence of instrumental effects or blurring of the atmosphere, it gives (approximately) the minimum angular separation between two objects that can be resolved. The ...
ProfRob's user avatar
  • 149k
6 votes
Accepted

Do interstellar asteroids decelerate and eventually stop?

An object moving through the interstellar medium will experience a weak drag force. If the drag force is $f(v)$ the velocity will decline as $dv/dt=-f(v)/M$ where $M$ is the mass. In fluids $f(v)\...
Anders Sandberg's user avatar
6 votes
Accepted

What is a "fundamental location", and why is Mosting A defined as one for the moon?

Every coordinate system needs one point defined as exact and unambiguous - the fundamental location which all other location measurements in the vicinity are relative to. This can be the origin of the ...
planetmaker's user avatar
  • 18.9k
5 votes

A curious relationship between lunar periods and the solar year

The formula :- \begin{equation}\tag{A} \frac{1}{P_{sid}^{-1}-P_{syn}^{-1}} = P_{e} \end{equation} (where $P_{e}$ is the sidereal period of the Earth in its orbit around the Sun) can be derived with ...
Ross Ure Anderson's user avatar

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