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1500 questions
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How long does it take for a white dwarf to cool to a black dwarf?
I was reading on white dwarfs, and I came across this sentence—
Without energy sources, the white dwarf cools to a black dwarf in a few billion years.[1]
However, when I looked into the Wikipedia page on White dwarf, it says
Because the length of…
S R Maiti
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Is parallax a "technique to measure the star distances" or a "tiny shift in star's position"?
I am not completely sure whether the Parallax is a "technique to measure the star distances" or a "tiny shift in star's position"?
The a book says two points about Parallax:
Astronomers have developed a variety of clever techniques for measuring…
Ahmed
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Has anyone ever tried to make a simple telescope using ice?
I grew up with long cold winters, and saw a lot of remarkably transparent ice formed by refreezing meltwater, both in puddles and ponds, and in large icicles. I'd always thought about making optical elements but never tried, as I knew getting a good…
uhoh
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16
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How can a red giant grow so big?
Supposedly when the sun becomes a red giant, it will grow big enough to swallow Earth.
However, this requires the radius of the sun to expand by a factor of approximately 215×, meaning its volume would have to expand 10,000,000×.
Maybe it's just me,…
user541686
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16
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Is a wavy path possible for a shooting star?
I was camping recently (May 2014), and observed several shooting stars (very fast, short lived), a few satellites (very slow, long lived) and lots of aircraft (flashing lights) in the night sky.
All of the shooting stars appeared normal, as very…
Rocketmagnet
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Why is the Earth-Moon distance not the same at each perigee/apogee?
I wonder why the Earth-Moon distance is not the same at each perigee/apogee. Isn't the Moon's orbit a fixed ellipse with Earth at one of the foci? If it is so, shouldn't the distance at perigee/apogee be a fixed value?
Michael Teoh
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Why is the solar system often shown as a 2D plane?
Whenever I have learned about the solar system I always see the orbits displayed as a virtually flat plane.
Are all of the orbits in the solar system really like this? If so, why? It seems like a rather large coincidence for all of our planets +…
David says Reinstate Monica
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A good telescope for the viewing of Nebulae, Stars and Planets
So, I am a 15 year old interested in astronomy. My father used to have a reflector telescope, but was never so serious about it that he could recommend me a good telescope. I am looking to buy a telescope up to £400 (possibly £500) and would like…
Harry Kitchener
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What is this bright "glow" in the center of galaxies?
It was always my belief that at the center of many galaxies, there are supermassive black holes. If this is the case, then we should not see a "light" coming out from the center since light get's sucked in black holes. Doing a quick search of…
K Split X
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Relativistic effects in stellar dynamical systems
I am curious, if anybody knows of any stellar dynamical systems/environments, where relativistic effects could play a dynamical role on the motion of these stellar systems? As a subquestion - are there any known important weak, but cumulatively…
Alexey Bobrick
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How exactly does inflation convert random gravity fluctuations into coherent gravitational waves?
In the course of this very enjoyable press announcement, it is mentioned that inflation can create gravity waves by amplifying gravity fluctuations.
I do not properly understand this statement. I always thought that quantum fluctuations (fluctuation…
Dilaton
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16
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Will the Earth ever be tidally locked to the Moon?
From my basic understating,
Momentum is being transfered from the Earth's rotation to the Moon's orbit by tidal friction. The Earth's rotation slows down and the Moon receedes from the Earth as it moves into a higher orbit. This will continue until…
TheWhaleOnPluto
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Boötes Void numbers, 2016
As a general science (hence Wikipedia!) reader, the latest information I have is that 60 galaxies "have been found and counted" inside the Boötes void, this of 1997.
(1) What is the latest count of galaxies "known" inside the Boötes void?
The Boötes…
Fattie
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Is the Earth-Sun distance 1.012 AU?
Wolfram Alpha's query: Sun Earth distance in AU gives:
1.012 au (astronomical units)
They definitely use this value in other places too - e.g. Earth-Sun $L_1$ distances from Earth and from Sun don't add up to 1 AU - they are 0.01009 AU and…
SF.
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What does the Sun's orbit within the Solar System look like?
Everything in the Solar System revolves around the "barycenter": the overall center of mass. This barycenter is not in the center of the Sun. Some articles and essays I've read go so far as to suggest that the position of the barycenter does not…
Ricky
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