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1500 questions
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Why is the observable Universe larger than its age would suggest?
The age of the Universe is estimated at 13.8 billion years, and current theory states nothing can exceed the speed of light, which can lead to the incorrect conclusion that the universe can't have a radius of more than 13.8 billion light…
GDVS
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What is a parsec and how is it measured?
Astronomical units of measurement are mostly pretty straight-forward:
Astronomical Units refer to the mean Earth-Sun distance (~150 million km or 93 million miles)
Light years are the distance light travels in a year (~9.46 × 10^12 km)
Another…
user8
29
votes
3 answers
If months are based on the moon, then why are the months longer in the Gregorian calendar than lunation?
What I have always thought / known is that:
Days are based on the period of rotation of the earth.
Months are based on the moon.
Year is the time taken by the earth to make one revolution around the sun.
But if we take a look at the lunation it…
lunisolar
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A moon in eccentric orbit dipping below Roche limit
Let's imagine (or do we know one?) a moon in a very eccentric orbit around a planet, with periapsis below the Roche Limit. How would it behave? Would it break apart when speeding past the planet, then reform back as it spends a long time near the…
SF.
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How is Uranus' north pole defined?
The rotation axis of the planet Uranus is tilted by 98° compared to its plane of orbit. This means that the north pole of Uranus is "under" the ecliptic compared to the north pole of other planets.
Why was the value of 98° chosen, rather than 82° ?…
usernumber
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What is this web on the surface of the Sun?
I was going through my Social Media Feed and found the attached post too frequent. The caption reads this is the best image of our Sun. Just as an example, the Universe Today's This is the Highest Resolution Image Ever Taken of the Surface of the…
Pranay
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Why does the 70-solar-mass black hole in the LB-1 system challenge current astrophysics?
Recently scientists discovered a large stellar-mass black hole, which (previously) they believed that it shouldn't be possible in our galaxy!
Source
An international team of scientists say they have discovered a
stellar-mass black hole with a…
Junaid S.
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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? Or are binaries the ones that survive, and…
RonS
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When will the number of stars be a maximum?
There are very roughly a "mole" of stars in the universe. Wikipedia quotes an estimate of $3 \times 10^{23}$ though the number is associated with some debate and uncertainly.
I'd like to know if there are estimates of when the number of stars in the…
uhoh
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We know what a nova is, but how?
I work with astrophysicists and require some basic knowledge of many astronomical sources, however research priorities often demand that most of human knowledge on a subject be taken for granted.
I am currently researching galactic novae, and I find…
Sam
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Is the dark side of the earth protected from the risks of solar flares?
Many speculate about the possibility of another “Carrington event”. Without getting into unrealistic scenarios, I ask myself the following question: would electronic lines and the equipment connected to them be safe if a large CME occurred, say,…
BertS
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28
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When stars explode after running out of fuel, why are new stars born from the remnants?
I'm not a physicist or have a very good physics background but I've often wondered why there are new stars that are born in the nebula which was created after the parent star has exploded. As I understand, a star (at least those which have enough…
artas2357
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Which planet came first in our Solar system?
I always wonder which planet came first in our solar system? Sources suggest that Jupiter might be the first planet in our solar system, but how did our solar system evolve into an 8 planet system?
Kavin Ishwaran
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Is the science in "Don't Look Up" realistic?
In the new movie "Don't Look Up", astronomers discover a comet in the outer Solar System that's going to hit the Earth about 7.5 months later. I think they calculate its trajectory within a day of discovering it, and they're virtually certain that…
Barmar
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Is the Astronomical Unit measured from the Sun's center or from the surface?
1 AU is defined as the distance between the Sun and the Earth, which is roughly 150 million km. But is this supposed to be from the Sun's center (Solar system's center of mass) or from the Sun's surface which already is almost 696 thousand km from…
kyjo
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