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1d
comment Can milky way be seen by naked eyes? Or any Galaxy?If yes then how and when?
How and when? By lying down on your back outdoors at night and opening your eyes. But you need to be away from city lights.
1d
comment Why does e.g. Hubble's secondary mirror not block part of the picture?
Why then, if I hold up a mirror at arms length in front of my face, does that "secondary" mirror hide a specific part of my field of view, when on a telescope it doesn't? Because light rays from nearby sources are not parallel, as they are from a distant star? But then what about an apparently large object like the Moon?
1d
asked Why aren't secondary mirrors offset to get rid of diffraction spikes due to the support vanes?
1d
comment How are boulders formed on asteroids?
So a boulder on a rubble pile asteroid is basically a tiny asteroid which got stuck there? Not something which formed on the rubble pile by some other process than how asteroids in general form in free space.
2d
comment Is there a general term for epicycles, deferents, and eccentrics in Ptolemaic astronomy?
@FreeConsulting I want to add to the defence of Ptolemy, that his calendar saved the life of millions of human beings, because of the better navigation and agricultural timing he provided. Physicists and engineers should give a bit more attention to the history of the giants on whose shoulders they stand today.
2d
comment Is there a general term for epicycles, deferents, and eccentrics in Ptolemaic astronomy?
@FreeConsulting That is unfair! Ptolemy did marvelous work according to his mission, which was to predict the apparent movements of the planets. It wasn't bad science, it was the best science ever, for 1500 years.
May
21
accepted Is radiation from neutron stars delayed by time dilation?
May
21
revised How would the solar system look in a Geocentric model?
added 50 characters in body
May
21
revised How would the solar system look in a Geocentric model?
added 50 characters in body
May
21
answered How would the solar system look in a Geocentric model?
May
21
comment How come, in our lifetime, we will see the first stars which ever formed?
I hope so too. But such simple intuitive logic doesn't always apply in this context. Maybe beyond the Big Bang we'll see younger galaxies instead of older, and 30 years from now people in the business will say: "Of course it's like this! Are you stupid or something?"
May
20
comment The Fermi paradox
@RobJeffries I agree with you, and I think the authors would too. It is a sensationalist piece obviously created just as a show off of creativity. I take it as a satire of the habitable zone definition. But it is the earliest date imaginable, so I think it should be at least a footnote to an answer.
May
20
answered “Up” and “down” in Space
May
20
revised Is radiation from neutron stars delayed by time dilation?
Corrected and shortened the headline.
May
20
comment Is radiation from neutron stars delayed by time dilation?
Corrected the spelling. I still refrain from using the "proper form" which is dilatation because I don't want to sound like a shoemaker (i.e. a "snob") in a topic I don't know much about. Strange stars might exist within neutron stars.
May
20
revised Is radiation from neutron stars delayed by time dilation?
edited title
May
20
comment The Fermi paradox
@RobJeffries The paper author "Loeb says rocky planets could have existed at that time, in pockets of the Universe where matter was exceptionally dense, leading to the formation of massive, short-lived stars that would have enriched these pockets in the heavier elements needed to make planets." They had to make something up. After all, they did find a new "habitable zone".
May
20
asked Is radiation from neutron stars delayed by time dilation?
May
20
revised The Fermi paradox
added 68 characters in body
May
20
answered The Fermi paradox