View Full Version : Hubble's View of Supernova Remnant Cassiopeia A

2006-Aug-29, 05:54 PM
NASA's Hubble Space Telescope took this photograph of supernova remnant Cassiopeia A, one of the youngest remnants we know of in the Milky Way. The image was made up of 18 separate photos taken by Hubble using its Advanced Camera for Surveys, and it reveals the faint swirls of expanding debris. Astronomers believe the star that used to live at the centre exploded as a supernova about 340 years ago (as well as the 10,000 years it took for the light to reach us).

Read the full blog entry (http://www.universetoday.com/2006/08/29/hubbles-view-of-supernova-remnant-cassiopeia-a/)

2006-Aug-30, 08:23 PM
Isn't it more precise to say that, "the light from the supernova we first saw 340 years ago began when the star went supernova 10,000 years ago"

The way it currently reads seems to indicate the star went supernova 340 years ago but it's light took 10,000 years to reach us.

2006-Aug-30, 08:32 PM
Can someone please explain the how the age of 340 years and 10,000 light years distance be reconciled, is the real age 10,340 years?

Thank you


2006-Aug-30, 08:46 PM
The Bad Astronomer, super-psychic that he is, anticipated these questions:

BA Blog: Mi Cas A es su Cas A (http://www.badastronomy.com/bablog/2006/08/29/mi-cas-a-es-su-cas-a/)

Footnote: Yes, I know– some of you will think that it didn’t blow up in 1680, that’s just when the light reached us, and it really blew up 10,000 years ago. I disagree. We cannot say anything about that event until the light reaches us, and in a real sense that event has not happened until the light reaches us. Time flows like light, I sometimes say, meaning that the event itself happens when the light reaches us. So it is acceptable to say that the explosion actually happened in 1680.

2006-Aug-30, 11:04 PM
i suppose if you received a delayed letter telling you about the Sinking of the Titanic, i guess you would wonder if there were any survivors (even though you would know none are alive).

I guess its better to give a earth time date, say, November 11, 1572 AD, (or August 16, 1680) and a location, ie situated 10,000 light years away. rather than saying 434 years ago (or 326 years ago)...