Astronomy Picture of the Day

NASA ^ | 01/01/07 | T. A. Rector

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NGC 6960: The Witch's Broom Nebula
Credit & Copyright: T. A. Rector (U. Alaska), WIYN, NOAO, AURA, NSF

Explanation: Ten thousand years ago, before the dawn of recorded human history, a new light must suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was an exploding star and record the colorful expanding cloud as the Veil Nebula. Pictured above is the west end of the Veil Nebula known technically as NGC 6960 but less formally as the Witch's Broom Nebula. The rampaging gas gains its colors by impacting and exciting existing nearby gas. The supernova remnant lies about 1400 light-years away towards the constellation of Cygnus. This Witch's Broom actually spans over three times the angular size of the full Moon. The bright star 52 Cygnus is visible with the unaided eye from a dark location but unrelated to the ancient supernova.

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Full size image here.
Dial up warning: 3.4 MB

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[xJones]

How beautiful, thanks.

[indcons]

Very pretty...thanks for posting.

[xcamel]

Nice..One I had not seen.

[JockoManning]

Thanks. Lovely. BTTT.

[Quix]

Beautiful.

Thanks.

Too beautiful to be a witch's broom.

More like an angel's veil, to me.

[Reaganesque]

Wow! Nice!

[sit-rep]

I'm no astronomy/physics whiz, so I must ask the question...

Do they know for sure that the speed of light is the same in space than in atmospheric conditions?

Poll...

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All theories and studies indicate that C is an absolute, one of the very few in our world.

[sit-rep]

Thanks for the straight reply... I had my flame retardant suit on just in case!! ;)

[outofsalt]

I thought this nebula originated in Chicago and spread to Arkansas, DC and Chappaqua.

[Mad_Tom_Rackham]

Wonderful!

[hypatia]

Gorgeous!

[kanawa]

It is a constant in empty space. Nothing can exceed the speed of light in empty space.
It does go slower through the air or other translucent materials depending on the refractive index of the material
Air speed is only slightly less than c, through water or glass as much as 2/3 to 3/4 of c.

[PSYCHO-FREEP]

But there are objects that light must bend around in order to continue. Einstein illustrated this as the "bending" of Time/Space. Also referred to as Gravity.

This alone would slow the speed of light over great distances. One would think that the speed of light would vary then, given the distance it has to travel.

(String Theory not withstanding)

[RightWhale]

Do they know for sure that the speed of light is the same in space than in atmospheric conditions?

Light is slower in the atmosphere and even slower in water or glass. But the assumption that light moves at the speed of light in the vacuum is very major and is still an assumption. The theory of relativity plays with this concept a lot, so much that you could say the speed of light in a vacuum is not in general the speed of light in a vacuum. You can certainly not make the jump to the idea that nothing can go faster than the speed of light.

[PSYCHO-FREEP]

In Einstein's time, most Scientists agreed that space was a vacuum. But now, there are strong indications that there are dark matter particles driving the accelerated expansion of the Universe. In a vacuum, the Universe would expand at a constant rate, also referred to by Einstein as the "Cosmological Constant". But due to indications in "Red Shift" the Universe is accelerating.

[RightWhale]

It only looks that way because that is what we expect to see. Like a lot of folk science such as that earth's mag field is caused by the iron core, we see what we are prepared to see.

[Enterprise]

Simply beautiful!!