Comments on: Crabby Hubble

By: Rural Rambles: Larry Ayers’ Weblog » Tangled Bank # 43

Rural Rambles: Larry Ayers’ Weblog » Tangled Bank # 43 — Wed, 14 Dec 2005 16:59:54 +0000

[...] Crabby Hubble [...]

By: Pittsburghmuggle

Pittsburghmuggle — Sun, 11 Dec 2005 19:30:47 +0000

I like the double star in the lower left corner of both animations – you can see the smaller star moving!

By: Jon Niehof

Jon Niehof — Fri, 09 Dec 2005 19:26:17 +0000

Irishman–good question! In fact, there have been times when composition and doppler were confused, resulted in the supposed “discovery” of substances like “nebulum.” We know it’s a Doppler shift because the line spacing is quite unique and there are a *lot* of them. If every single one of dozens of lines is shifted by an amount that indicates the same velocity, and dozens of lines of some element are shifted by an amount that *also* indicates the same velocity, Occam’s Razor (as well as general probability) suggests that it’s more likely a doppler-shifted spectrum of elements we already know, rather than some exotic material that *just happens* to be like that.

By: JusANuttaBackYahdah

JusANuttaBackYahdah — Fri, 09 Dec 2005 02:05:29 +0000

Telescopes are a time machine, moonflake, but did you know they work in both directions? I’m just returning from a small star party I held for a local kids group. I always enjoy showing something like the Andromeda galaxy; telling the folks that the light took 2.5 million years to reach us which is always followed by a WHOA!!! It’s funny though, I always see the future when I get a kid to react like that
One WHOA-fact about the Crab not mentioned is that various records of the sky event that created this nebula show that the supernova was naked eye visible in daytime skies for some twenty-odd days. Now that’s a WHOA!
Clear skies

By: Irishman

Irishman — Thu, 08 Dec 2005 16:44:41 +0000

Here’s what bugs me about the Doppler shift in spectra – how is it that we conclude that the spacing of gaps and lines is shifted and not from a different combination of elements? For instance, I saw a TV show discussing this. The show came up with a reenactment of some 19th century astronomer making discoveries, and showed him and his lab assistant operating the telescope, showed him taking the image and then going to develop it. They spent five minutes on this silly reenactment, and then squeezed in one example of comparing the spectra to show the shift. To me it would have been much more informative to skip the silly acting and show a dozen spectral comparisons and demonstrate how the comparisons are made and why scientists interpret the changed patterns as shifts rather than just different combinations.

By: moonflake

moonflake — Thu, 08 Dec 2005 12:38:42 +0000

The idea that when we look up at the sky we look back in time, to the universe as it was thousands or millions or billions of years ago… we already have built time machines, they’re called ‘telescopes’. Love it.

By: Marlayna

Marlayna — Thu, 08 Dec 2005 10:31:41 +0000

Thanks, I think I got it