# Tag Info

1

This is a very broad question: no comprehensive answer from me, but here are a couple of brief thoughts: There is a predicted cosmic neutrino background, analogous to the cosmic microwave background. Neutrinos decoupled at 1 second after the big bang, filling the universe with neutrinos that should have now cooled to a temperature of about 1.9 K. ...

0

It's true that planets usually don't flicker, or twinkle (or scincillate, as astronomers like to call it). The reason is that they are close enough that they are actually seen as a disk with a larger diameter than the atmosphere can "wash out" (the seeing disk). Stars, on the other hand, are point sources, and this point jumps back and forth on the sky, as ...

5

The answer is: frequently. There are many amateur astronomers that make it their ambition to discover new supernovae or to observe and report on new variable stars. As an example, let me cite amateurs Robert Evans, who apparently holds the record for most supernovae found by visual observation, or Tom Boles, who holds the record for supernova discoveries by ...

0

Put simply, it is because the objects that make up the Oort Cloud, remnants from the formation of our sun, are both too small and too faint for us to detect. They are faint because of their vast distance away. There is minimal absorption of the sun's light and even less is reflected back. So little light is reflected back that there is nothing for even our ...

1

In the night sky in 10,000 years, two things will have changed in relation to the stars. The first, the rotational axis of the Earth will have changed, shifting the celestial sphere. The second, the stars themselves will have moved a bit relative to each other due to proper motion. So, the night sky will be quite different in 10,000 years, but still ...

2

Yes. When light moves through the expanding space, it loses energy and becomes redshifted. As galaxies form, they a emit a lot of UV light, and are often detected from there emission at the so-called Lyman $\alpha$ light, which has a wavelength of 1216 Å. Galaxies began forming just a few hundred million years after the Big Bang. Since then, the Universe ...

1

This is because of something called the Doppler effect. As something moves away from us, the Electromagnetic waves it releases will have a longer wavelength. Also, because of Hubble's law, galaxies that are further away have an increased velocity, making the red shift even more pronounced.

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It may shave off 1 or 2 magnitudes, but it depends on many factors: nature of the object (star, nebula, galaxy), altitude (higher altitude has less light scatter), transparency, etc. There's no One Single Answer To Rule Them All. Light pollution from artificial sources has a greater impact in most cases.

-1

I know it's a bit late for the UK eclipse, but for future reference: Welders goggles do not cut out the same frequency of light that Mylar/Black Polymer eclipse glases do. Arc welding glass #14 is much darker than brazing welders glass but there is no guarantee that they will block the Sun's ultra-violet and infrared rays. The problem is there are no ...

1

Wasn't it pretty obvious to a careful astrologer a thousand years ago, that the Moon does not have a circular orbit and does not describe epi-cycles? The ancient Greek model of the motion of planetary bodies remained unchallenged for almost two millennia, so obviously not. Hipparchus' model did a fairly good job dealing with the elliptical motion of ...

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