All Questions
14,651
questions
11
votes
1
answer
242
views
What is the current routine of modern astronomy? [closed]
With about all visible stars catalogued, measured and photographed it seems that chapter is closed. I realize currently while amateur astronomy is big on cataloguing all asteroids in the Solar System, ...
11
votes
1
answer
2k
views
What is the bright orange star?
After reading this NASA article on Tarantula's Nebula of this image:
What is the really bright orange star in the center or upper-left of the young blue stars? The second link further provides ...
11
votes
2
answers
514
views
Could a star closely orbit a black hole long enough for the star to have lost 0.5B+ years to time dilation?
I was wondering how stable a close star-black hole system could plausibly be, and thus how much time a star could plausibly miss out on (from an outside observer's perspective) due to being in an ...
11
votes
2
answers
4k
views
How does the Moon move in the "night" sky as seen from the poles?
A photo in the NYTimes article Ice Surveys and Neckties at Dinner: Here’s Life at an Arctic Outpost has got me thinking.
During the winter months at either the north or south pole, when it is ...
11
votes
1
answer
373
views
How the position of this black hole known?
How do scientists know the positions of black holes?
Observe the highlighted area in the image:
11
votes
1
answer
551
views
Why can we detect gravitational waves?
Now that LIGO has finally measured gravitational waves using a huge laser interferometer, to me, the question remains, why was it possible? As it is explained in many news articles, gravitational ...
11
votes
3
answers
737
views
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)?
11
votes
2
answers
19k
views
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 ...
11
votes
2
answers
3k
views
How did water get on Earth
I recently read that water more than likely got here by comets (carrying water) hitting the Earth. However it also it says the impact of a comet hitting the Earth is much greater than an atomic bomb. ...
11
votes
2
answers
3k
views
Why does iron consume more energy in the fusion process than it produces?
I understand that once a star starts fusing iron, it's doomed to collapse because iron fusion requires more energy than it releases in the process, allowing the opposing gravity of the star to cause ...
11
votes
1
answer
5k
views
Does the Moon's magnetic field affect Earth's magnetic field?
I wanted to ask a question; it's simple but I cannot find any possible and perfect solution.
Earth has poles, North and South. By which we can get directions using a compass or a needle compass, but ...
11
votes
1
answer
1k
views
Did this satellite streak past the Hubble Space Telescope so close that it was out of focus? If so, how close was it?
The new Nature Astronomy paper The impact of satellite trails on Hubble Space Telescope observations (Kruk et al. 2023) describes an AI-based object classification method used to find satellite trails ...
11
votes
1
answer
607
views
Was GRAVITY built to look at one star?
GRAVITY (shown below) is a interferometric combiner of near infrared light from four very large telescopes called The Very Large Telescope in order to make careful astrometric measurements near the ...
11
votes
1
answer
2k
views
Why the blank wedges in this very early 21 cm map of the Milky Way? (Oort et al. 1958)
Jan Oort was a pioneer in radio astronomy. Wikipedia says:
It has been written that “Oort was probably the first astronomer to realize the importance” of radio astronomy. “In the days before radio ...
11
votes
5
answers
3k
views
Where to obtain Tycho Brahe's data?
I would like to obtain Tycho Brahe's data on Mars. What would be an authoritative source? One source I could find is this page (the data is given as an Excel file) but I have no idea can that be ...
11
votes
2
answers
582
views
Recommendation for introductory cosmology text
I am looking for recommendations for an introductory text (or texts) on cosmology on the advanced undergrad or beginning grad level. I am coming from primarily a physics undergrad background (doing ...
11
votes
2
answers
349
views
Does the Moon Have Enough Water for Robert Zubrin's Mars settlement Plan To Work?
In Robert Zubrin's "The Case for Mars" he outlines a plan to settle Mars by(among other things) finding water and using electrolysis to break up water into Hydrogen and Oxygen. This provides fuel for ...
11
votes
2
answers
776
views
How to calculate the movement of the object passing near other object in space?
Assume object A is moving through the space and is passing near the other object (B). Assume the gravitational influence of other objects can be ignored. How to find the equation describing the ...
11
votes
1
answer
541
views
How did astronomers get rid of microwave radiation from stars and galaxies in picures of the CMB?
Images of the CMB show no sign of stars or galaxies. If they did, shouldn't the Milky Way be a bright band dividing the CMB into hemispheres? Black body radiation in a given wavelength/frequency range ...
11
votes
1
answer
444
views
Can the energy transport by radiation occur in the convection region of a star?
I am new to stellar astrophysics and trying to understand the energy transports in the interior of stars.
Can the energy transport by radiation occur in the convection region of a star?
Here are my ...
11
votes
3
answers
536
views
Why are telescopes positioned in Lagrange points?
In this Wikipedia article about the list of space telescopes to be launched (which I assume is exhaustive), of the 11 telescopes yet to be launched, 6 will be positioned at the Sun-Earth L2 Lagrange ...
11
votes
1
answer
1k
views
How much more life could the Sun acquire via star lifting?
It has been proposed before that we could use this technique to remove hydrogen from the Sun to lower it's rate of fusion and extend it's life, so it doesn't fry our planet.
I am wondering how much ...
11
votes
1
answer
586
views
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 ...
11
votes
1
answer
739
views
What was the "brilliant new star in Aquila" on June 8, 1918, just after the solar eclipse?
This great answer about the US Naval Observatory's $3,500 expedition to Baker City Oregon to observe the June 8, 1918 total solar eclipse links to the January 1919 Popular Astronomy article about the ...
11
votes
1
answer
2k
views
Why does lithium fuse at lower temperatures than hydrogen?
This is a basic question, but it's been bugging me. In the Wikipedia article for lithium burning, it states that:
Stars, which by definition must achieve the high temperature (2.5 × 10^6 K) ...
11
votes
2
answers
887
views
Would Adaptive Optics be Useful in Radio Astronomy?
The question Why is this video showing radio waves transmitted from a radio telescope? and this answer to it got me thinking. If atmospheric seeing at visible wavelengths is the result of refractive ...
11
votes
2
answers
3k
views
Is there an upper limit to the mass of terrestrial planets?
The exoplanet Kepler-10c has a mass between 15 and 19 times the mass of the Earth (making it comparable in mass to Neptune), and yet is thought to have a density of about 7g/cm3 and to be a ...
11
votes
2
answers
1k
views
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 ...
11
votes
3
answers
1k
views
What is the long term fate of the gas giants?
If I'm not mistaken, it is believed that the reason for such turbulent weather on the 4 outer gas giant planets is that the internal pressure is so great that it is generating heat, which is causing ...
11
votes
2
answers
754
views
Why all the photos from 67p are black and white?
I was wondering why every picture we saw on internet about Rosetta's landing on 67p just black and white ? Is there something i should know ?
11
votes
2
answers
4k
views
Time after sunset until star can be seen
Given a star's apparent location and apparent magnitude, how how many degrees below the horizon must the sun be for the star to be visible to the naked eye for an observer on Earth at a specified ...
11
votes
4
answers
10k
views
Why is twilight longer in summer than winter and shortest at the equinox
I recently decided to set my alarm clock to wake me up when it is "dark" out. In the end, I decided to set my clock to the earliest time that nautical sunrise is in my state (Illinois) and stick with ...
11
votes
2
answers
4k
views
How does a telescope measure parallax angle?
I know how stars' distances are measured by using parallax, but I want to know how the actual telescope measures the parallax angle. Any helpful links/ explanations are needed.
11
votes
2
answers
537
views
Why is the Earth's center still hot after millions of years? [closed]
Why didn't the center of the earth cool after millions or billions of years? What keeps it hot?
11
votes
1
answer
524
views
How do astronomers calibrate the intensity scale of their spectrometers?
Discussion on Strange bump in solar spectrum taken with home-made spectrograph made me wonder: How do astronomers calibrate the intensity scale of their spectrometers? I mean, how to take in ...
11
votes
1
answer
2k
views
What are those stars that cross the galactic center?
I found this GIF by the European Southern Observatory (ESO) in the Wikipedia article on the galactic year, with the following description:
Visualisation of the orbit of the Sun (yellow dot and white ...
11
votes
1
answer
384
views
How do rocky objects between 1cm and 1m accrete to form planetesimals?
I am having a hard time gaining an intuitive understanding of some of the middle stages of planetary formation from a protoplanetary accretion disk.
I understand that microscopic dust particles may ...
11
votes
1
answer
939
views
Will James Webb see Population III stars?
I have heard that James Webb will see the first stars that our universe produced. Can I assume that we may see galaxies that are so young that all of the stars in them are population III?
11
votes
1
answer
541
views
Could asteroid 'Oumuamua actually be round?
News articles have mentioned that the recently discovered asteroid 'Oumuamua is theorized to be greatly elongated based on observations of brightness variation. However, this hypothesis seems to be ...
11
votes
2
answers
1k
views
Is there a better explanation of Hawking radiation?
I'm writing a piece on Hawking radiation, and find I have something of a problem. The "given" explanation which I find on Wikipedia and elsewhere is unsatisfactory:
"Physical insight into the ...
11
votes
3
answers
1k
views
How do I know, mathematically rather than from observation, if a moon is full?
I know about the equations to describe the orbit of a moon around a planet. I know the moon's semi-major axis and eccentricity, and the same for its host world with the star they orbit.
Is there any ...
11
votes
2
answers
1k
views
How was Earth's "quasi-satellite" 2016 HO3 "first spotted" and it's orbit determined?
Under a question I asked a few days ago Have there been any documented mini-moons since 2006 RH120? @Hobbes mentioned the recent news about 2016 HO3 - a near-Earth asteroid that stays near Earth ...
11
votes
2
answers
975
views
Do black holes die?
I know of stars actually dying (exploding as a supernova) but I have never heard of what happen to black holes. Do they continue to live forever, waiting there for more matter to absorb? Do they ...
11
votes
2
answers
2k
views
Are we moving ever closer to the center of our Galaxy due to a super massive black hole?
I've seen in documentaries that at the center of each galaxy is a super massive black hole which holds the galaxy together.
Since black holes have such a strong pull, are we slowly being pulled in ...
11
votes
1
answer
472
views
How does a star's rotation affect a star on the main sequence?
I searched and have found that the questions mainly focus on neutron stars, white dwarfs and black holes. This was not what I want.
Basically, the bigger the star's mass is, the more intense its ...
11
votes
2
answers
1k
views
How easy would be to see the Moon from Mars?
This question arises from "What planet is better than earth to infer solar system configuration?", where one of the answers pointed that it's easier to discover the Moon from Mars than discovering the ...
11
votes
1
answer
548
views
Will gravitational waves too far away ever reach us?
Gravity is the curvature of spacetime, and its effects travel at lightspeed. However, space is expanding; eventually, light from distant galaxies will become more and more redshifted, and we will no ...
11
votes
2
answers
801
views
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 ...
11
votes
2
answers
6k
views
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 ...
11
votes
1
answer
3k
views
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 ...