Search found 17392 matches

by Chris Peterson
Wed Aug 22, 2007 7:32 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: What Happens If Our Sun Dies..
Replies: 14
Views: 6944

I thought space was darn cold. :lol: Space in the Solar System is pretty bloody hot. In Earth orbit, say where you find the ISS, the temperature is around 1000K. between the planets, it can reach nearly 1 million K. Of course, the particle density is so low that you transfer almost no energy convec...
by Chris Peterson
Tue Aug 21, 2007 2:27 am
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: What Happens If Our Sun Dies..
Replies: 14
Views: 6944

Well i dont think earth might survive if the sun will become a white drawf soon.. It is possible for the Earth as a planet to survive the process of our Sun becoming a white dwarf. A red giant is tenuous and cool enough that a planet might continue to orbit inside it. However, the Sun will also hav...
by Chris Peterson
Mon Aug 20, 2007 7:42 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: What Happens If Our Sun Dies..
Replies: 14
Views: 6944

Re: What Happens If Our Sun Dies..

But what happens,if our sun dies n become a neutron star..? Will all the gravity be lost? Will all the planets,collapsed n become unarranged? Will we collide with other planets..? Will our planet,be dark forever..? Our sun is not massive enough to become a neutron star. It will eventually become a ...
by Chris Peterson
Mon Aug 20, 2007 4:50 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Discussion of APOD 15 August 2007: Mysterious Streaks
Replies: 97
Views: 77906

My latest re run with Guide 8 comes in agreement with MaG's research:- IR35 (#24966) 03.23:24 - 03.23:38 (EEST) IR97 (#24967) 03.32:40 - 03.32:48 " IR5 (#24795) 03.41:54 - 03.42:06 " IR6 (#24794) 03.50:52 - 03.51:25 " IR7 (#24793) 03.59:54 - 04.00:28 " I question these results. ...
by Chris Peterson
Sun Aug 19, 2007 11:47 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Discussion of APOD 15 August 2007: Mysterious Streaks
Replies: 97
Views: 77906

Re: Streaks In Orion

IRIDIUM 8 (#24792) 00:40:38h UT (Lowest streak. Slight flare) IRIDIUM 51 (#25262) 00:49:55h UT (Flare) IRIDIUM 7 (#24793) 00:56:05h UT (Small duration flare) IRIDIUM 6 (#24794) 01:06:56h UT (Faint trail) IRIDIUM 5 (#24795) 01:08:21h UT (Top most very faint trail) Unfortunately, these times are not ...
by Chris Peterson
Fri Aug 17, 2007 4:04 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Discussion of APOD 15 August 2007: Mysterious Streaks
Replies: 97
Views: 77906

Re: Horizontal Streaks

If you look closely you will notice there are more than 5 streaks in the image... they begin near the base of the photo and track toward the upper-left corner... at the point where the three brightest streaks are located they shift direction and begin tracking toward the upper-right corner of the i...
by Chris Peterson
Fri Aug 17, 2007 1:03 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Discussion of APOD 15 August 2007: Mysterious Streaks
Replies: 97
Views: 77906

Which is why I posted my lens/filter scratch question. Sometimes the simplest of solutions is probably the most likely. :) As we are all interested in the search for knowledge, I don't think it would be too embarrassing for the author to say, "oopsy, I just took a look, and there are scratches...
by Chris Peterson
Fri Aug 17, 2007 12:59 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Discussion of APOD 15 August 2007: Mysterious Streaks
Replies: 97
Views: 77906

Re: Calsky

1) Check location. I searched: Turkey, than Beynam.. it gives me: Beynam, Turkey WGS84: Lon: +32d53m45.0s Lat: +39d41m21.0s Alt: 1324m 2) Check date and time: Date 12. 8. 2007, time - the best is maybe UTC, so than you must enter 0:15 for beginning and 1 hour span (to 1:15 UTC).. I think you've mad...
by Chris Peterson
Thu Aug 16, 2007 8:30 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Discussion of APOD 15 August 2007: Mysterious Streaks
Replies: 97
Views: 77906

Re: About the composite image

I submit: Location Beynam near Ankara, Time: 4:00 - 7:00 local time. and I receive this in Calsky.com: 4:23:26 Iridium 35, -1,9 mag (in Orion) 4:32:45 Iridium 97, -4,7 mag (in Orion, spare satellite, time and mag can be inaccurate) 4:42:04 Iridium 5, -2,6 mag (in Orion) 4:51:19 Iridium 6, +1,2 mag ...
by Chris Peterson
Thu Aug 16, 2007 1:53 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Discussion of APOD 15 August 2007: Mysterious Streaks
Replies: 97
Views: 77906

reminds me of this discussion. http://asterisk.apod.com/viewtopic.php?t=249 Yeah, me too. Just like in that case, we've got one or two simple, straightforward possibilities, and a discussion that takes on a life of its own as people try to come up with off-the-wall, crazy theories- many based on a ...
by Chris Peterson
Wed Aug 15, 2007 11:03 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Discussion of APOD 15 August 2007: Mysterious Streaks
Replies: 97
Views: 77906

Re: Please, somebody explain me.

Both the stars and the trees have pretty well defined positions in this photograph, which I think is incompatible with the fact that Earth rotates about 10 degrees around its axis in the term of 40 minutes. The trees look well defined, then the camera was rotating with Earth and the stars should ha...
by Chris Peterson
Wed Aug 15, 2007 4:42 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Discussion of APOD 15 August 2007: Mysterious Streaks
Replies: 97
Views: 77906

Where Chris comes up with the idea of stacking is news to me, and not listed about the image. The same image was submitted to Spaceweather.com with the following comment: I took a 100-picture series of 105-second wide angle pictures using a Canon EOS 300D camera at ISO1600 and a 10-22 mm lens at 10...
by Chris Peterson
Tue Aug 14, 2007 8:13 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: LASER beam (APOD 31 July 2007)
Replies: 21
Views: 7992

I'm curious how astronomers go about detecting naturally-occurring stellar lasers. Are they detecting the coherence of the laser light, or simply the strong peak emission frequency in the stellar spectrum? As noted earlier, laser light loses its coherence quickly with distance, so that cannot be us...
by Chris Peterson
Tue Aug 14, 2007 7:33 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Discussion of APOD 15 August 2007: Mysterious Streaks
Replies: 97
Views: 77906

Re: Discussion of APOD 2007 August 15: Mysterious Streaks

What are they? Thoughts? Normally, when you see short streaks through Orion they are geosynchronous satellites. But in this case, the direction of travel is too far off the ecliptic, and the angular speed is too great (assuming each streak was caught in a single 105-second exposure). Supposedly, th...
by Chris Peterson
Tue Aug 14, 2007 1:25 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: LASER beam (APOD 31 July 2007)
Replies: 21
Views: 7992

Re: APOD - laser strike at galactic centre

Wrong wrong wrong Coherence is whenphotons are "in step" and have a definite phase relation. Unrelated to the point you are making. The question I was addressing suggested that the coherence of a laser could be used as a signature of an artificial source. I merely pointed out that coheren...
by Chris Peterson
Thu Aug 02, 2007 4:13 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Cratering on Dione question (APOD 01 August 2007)
Replies: 24
Views: 7142

Re: Cratered from behind

Seems to me that the more heavily cratered side of Dione should be the trailing side.Right? Dione has about an equal chance of hitting a prograde bit of debris on the leading or trailing edge. But there's bound to be lots of retrograde debris as well, which will selectively hit the leading edge. Al...
by Chris Peterson
Thu Aug 02, 2007 4:06 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Cratering on Dione question (APOD 01 August 2007)
Replies: 24
Views: 7142

Equate potential energy with kinetic energy at the planet's surface, solve for speed, and you get a figure of the order of km/s, which is a lower bound on impact speed (for airless worlds). And no, a planet or large moon can't "sneak up" on asteroids traveling at almost the same velocity ...
by Chris Peterson
Thu Aug 02, 2007 12:57 am
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Hello and a Question
Replies: 3
Views: 3327

Re: Hello and a Question

Q: I have observed, during my several months here, that the moon does not rise from a predictable spot on the horizon each night. In an urban setting you can't see this, but here I have a clear view of the horizon. One night it rises directly across the lake between two, large, oak trees and the ne...
by Chris Peterson
Wed Aug 01, 2007 10:49 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: LASER beam (APOD 31 July 2007)
Replies: 21
Views: 7992

Re: APOD - laser strike at galactic centre

Ref. todays picture and comment regarding the effect of shining a laser at the galactic centre. Forgetting for the moment the distances and hence time frames involved and given that we, with our limited technology, are able to detect water molecules in distant atmospheres, is it not the case that n...
by Chris Peterson
Wed Aug 01, 2007 2:49 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Tidal Tail of NGC 3628 (2007 Jul 27)
Replies: 19
Views: 6132

A suspected isolated black hole was supposedly discovered a few years ago when some astronomers noticed a small star suddenly brightened and then dimmed. It wasn't a white dwarf going nova. I can't remember offhandedly where it was reported. Of course, this claim was questioned, but finding a black...
by Chris Peterson
Tue Jul 31, 2007 3:34 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Tidal Tail of NGC 3628 (2007 Jul 27)
Replies: 19
Views: 6132

You can detect a solitary black hole only when one passes in front of a bright background object, such as a star. I don't think there's any case of a black hole being seen as a silhouette. They are just too small, even if one did happen to pass right in front of a star (which itself is unlikely). B...
by Chris Peterson
Mon Jul 09, 2007 7:48 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Night-Shining Clouds (2007 Jul 05)
Replies: 38
Views: 16439

Re: night shining clouds

yes, now i have a clear picture. when they are called "night shining clouds", that is a bit of a misnomer, because they are just as "night-shining" as for instance the moon - they receive their light from the sun, but because they are so very high up in the atmosphere, they can ...
by Chris Peterson
Sun May 20, 2007 10:36 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Dark Matter
Replies: 113
Views: 23330

Re: Dark Matter

Ah, my bad (I think). Could you explain how you used gravitational redshift to "scale the universe"? Sorry, my bad too. We scale the Universe with the cosmological red shift (it might have some other names, too). We do make allowance for the gravitational red shift when making stellar spe...
by Chris Peterson
Sun May 20, 2007 9:12 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Dark Matter
Replies: 113
Views: 23330

Re: Dark Matter

It is impossible to say that either matter or energy even exist. We simply find them convenient for explaining our observations. The Universe is full of things we've never touched directly, or had in the lab. That doesn't mean that we can't propose that their existence is likely. You're going to ha...
by Chris Peterson
Sun May 20, 2007 4:36 am
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Dark Matter
Replies: 113
Views: 23330

Re: Dark Matter

I know that EM fields exist in nature, and I can play with them in a lab. I have never seen an astronomer produce even a single gram of dark matter, or any controlled experiment like a neutrino experiment where "dark matter" was shown to have any effect on matter or photons. It is therefo...