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1500 questions
28
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4 answers
Could we carve a large radio dish in the Antarctic ice?
Could we carve a large radio dish in the Antarctic ice that could replace the Arecibo Observatory? Could this work, and what would be some potential limitations?
Joe
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How is it possible that we haven't discovered anything in the Oort cloud yet?
The Oort cloud is a hypothetical cloud of small icy bodies surrounding the Sun at more than 1000 AU. It is thought to be a vast reservoir of comets that occasionally get disrupted, sending comets towards the inner solar system.
I would guess that…
usernumber
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Is there a theoretical maximum size limit for a star?
Some stars are simply huge. Eventually, though, wouldn't there be simply too much pressure or mass for the star to sustain itself? Wouldn't it eventually collapse into a black hole?
Is there a theoretical upper limit on the size of a star, and what…
user19
28
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2 answers
Are we really star-stuff from the interior of collapsing stars?
Carl Sagan has said several times that we are "star-stuff".
One instance can be found in Good Reads' Carl Sagan > Quotes > Quotable Quote:
The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were…
uhoh
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Is it possible to mount a telescope on a plane? Is it beneficial?
I was wondering if any planes had mounted telescopes with the intent to observe the stars. I understand that the atmosphere itself can warp and hinder incoming light and even completely obscure views on cloudy days. Would it be possible to have a…
Magic Octopus Urn
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How did Ole Christensen Romer measure the speed of light?
How did Ole Christensen Rømer, who in 1676, shortly after Galileo's death, was said to have measured the speed of light as 220,000 km/s by timing the orbits of Io around Jupiter?
My only guess is the moon Io orbiting Jupiter is simply a clock. It…
Michael Lee
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Why is it okay to watch a sunset but not an eclipse?
People watch sunsets all the time. You don't see people using special "sunset glasses".
Yet with an eclipse, warnings are posted everywhere not to view it without special glasses.
Why is this?
End Anti-Semitic Hate
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Can a tectonically inactive planet retain a long-term atmosphere?
Can a planet be tectonically inactive and still retain a magnetosphere and protected atmosphere? How does that work?
How else could a planet retain a thick atmosphere like Earth's for extensive periods of time?
Note, I'm not asking on Earth science…
EveryBitHelps
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Why there is no smoke around the Sun?
Where there is fire, there is always smoke. So why there isn't any smoke near the Sun?
Pritam
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How much magnification is needed to see the planets of solar system?
I have a 3inch Newtonian reflector telescope with 300 mm focal length. I can use highest magnification of 75x using a 4mm eyepiece. But in 75x I can't see the details of Jupiter what was expected. Instead I see a little blurry image. Now I would…
Tanmoy Banerjee
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Which is brighter, Mars as seen from Earth, or Earth as seen from Mars?
At their closest flyby, Earth is ‘new’ and dim from Mars, and Mars is ‘full’ from Earth and brightest as seen from Earth.
When Earth is 39 degrees from the Sun then Earth is brightest as seen from Mars, then at a ‘crescent’, and Mars ‘gibbous’ to…
Mark Besser
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Why is the solstice the first day of summer, and not the central day?
Summer in the Northern Hemisphere starts on the day of the summer solstice. This is the day that the Northern Hemisphere receives more light from the Sun, due to the Earth's tilt. To my knowledge, the amount of light we receive is related to the…
DaniPM93
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Why did they decide to hit Dimorphos in the retrograde direction rather than prograde; was it a "coin-toss" or were there implications for observing?
CNN Space and Defense Correspondent Kristin Fisher does a really good job of summarizing the current state of the Double Asteroid Redirection Test early observational results for general public consumption. See video and screenshot below.
The…
uhoh
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Why, since Earth is in free fall towards Sun, are tides affected by Sun's gravity? Why aren't the oceans "weightless" like astronauts?
Astronauts on the space station do not feel the Earth's gravity at all; they are in free fall.
Since the Earth and all that's on it is in free fall toward the Sun, why would the oceans "feel" the Sun's gravity; i.e., why would the Sun affect the…
GulbenkianD
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Why is the summer solstice night shorter than the winter solstice day?
I was looking at the sunrise and sunset times where I live (Aberdeen, Scotland) and I noticed something odd: the time between sunrise and sunset in winter is longer than the time between sunset and sunrise in summer. I chose the solstice in both…
Nierninwa
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