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1500 questions
19
votes
4 answers
How do you call it when two celestial bodies come as close to each other as they will in their current orbits?
On Earth, we say Mars is in opposition when it is 180º from the Sun, which also marks the times when Mars and Earth come closest to each other.
Is there a specific name for such proximity events? For example, Saturn and Jupiter come to this maximal…
Pablo Tellería Cebrián
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19
votes
2 answers
Why aren't globular clusters disk shaped
I thought that solar systems and galaxies are disk-shaped because that is the most stable shape under gravitation. Globular clusters are very old, often times older than their host galaxies, so why haven't they flattened out?
griffins
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19
votes
2 answers
Why does the Earth have a z-component at the start of the J2000 epoch?
When I go to the NASA HORIZONS webpage
https://ssd.jpl.nasa.gov/horizons.cgi
and ask for the VECTOR coordinates of the Earth on 1 January 2000, it tells me that Earth has the following coordinates in the J2000 epoch:
X =-1.756637922977122E-01 Y =…
Bruce Bartlett
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19
votes
3 answers
Can I sense a bright star pointing an eight foot antenna towards it?
If I connect an eight foot Yagi or other comparable sized antenna to my oscilloscope and point the antenna at a bright star will I see a voltage on my oscilloscope?
I am not interested in turning the voltage into an image just wondering if I would…
Lambda
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19
votes
2 answers
What did I photograph?
Last night I was experimenting with my mobile phone shooting the night sky adjusting some settings like shutter time and ISO. One of the first pictures I thought was a complete failure, I only adjusted the shutter time to 30 seconds. But when I…
Ward Vanlerberghe
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19
votes
1 answer
Did we discover 10 or 12 new moons of Jupiter?
I saw multiple news sites reporting that a team discovered 12 new Jupiter's moons:
c|net - Twelve new Jupiter moons found, including one reckless one
Discover - Jupiter’s Got Twelve New Moons — One is a Bit of a Problem Child
While some other news…
Yannick Huber
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19
votes
2 answers
Whats the probability of a hazardous impact for human life on Mars?
Yesterday my sister and I have discussed the recent efforts of SpaceX to create a permanent colony on mars.
When coming to the several dangers of creating a habitat on a different planet, we got stuck on the probability of mars getting hit by an…
Starguin
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19
votes
1 answer
How far do we have to go to leave the galaxy?
How far is the sun from the edge of the galaxy in the following directions?
Moving along the shortest path parallel to the galactic plane (outward radially)
Moving along the longest path parallel to the galactic plane (radially presumably passing…
jpmc26
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19
votes
4 answers
How was the core temperature of the Sun estimated?
It was estimated that the heat inside the core of the Sun inside around 15 000 000 °C - this value is extremely enormous. How did scientists estimate this value?
Zoltán Schmidt
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19
votes
5 answers
Can impact craters on the moon act like giant radio telescopes?
Could large craters on the moon be used as reflective lenses for radio signals?
Acting like a large radio telescope reflecting radio waves to a satellite positioned over the crater.
Reactgular
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19
votes
2 answers
Do other planets in our solar system experience eclipses or is this unique to Earth?
Here on Earth we get to experience lunar and solar eclipses. Is this pure coincidence that everything happens to line up?
Do other planets in the solar system experience this phenomenon or is this something unique on Earth?
user96
19
votes
1 answer
Planning to revisit Arthur Eddington's experiment from 1919
As the fateful day draws closer, the United States will host a celestial event that comes once in three generations. I plan to witness this first hand at the exact center of greatest eclipse.
In the planning of this, I have immersed myself in the…
Bob Brooks
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19
votes
2 answers
What physical features determine if a planet is a major, minor or dwarf planet?
Like many, when I was growing up, we always were taught, hence always learned that there were 9 planets. However, recently, decisions were made and all of a sudden there were 8 major planets and a series of dwarf and minor planets.
What physical…
user8
19
votes
2 answers
Is there a gas giant orbiting TRAPPIST-1?
I would like to know if besides these planets, astronomers have discovered a gas planet like Jupiter in this system and if on these planets could exist life without a comet protector like Jupiter does for the Earth.
JeanPaul
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19
votes
6 answers
Why do stars become red giants?
Disclaimer: I’m not a career astronomer. I don’t own a telescope. I have no professional credentials. But I do find this stuff fascinating, and I consume all the astronomy documentaries I can.
So, I’ve watched lots of documentaries describing…
Zearin
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