Archives for the 'astronomy' Category
Late sunrise
Published on 22 Dec 2009 at 2:10 pm.
1 Comment.
Filed under astronomy.
Yesterday, December 21, was the Winter Solstice here in the northern hemisphere. On that day, the Earth was in the part of its orbit where its north pole was tilted as far away from the Sun as it will get this year. The Sun appeared as far south in the sky as it will. That […]
Cosmic Rays
Published on 18 Oct 2009 at 4:01 pm.
3 Comments.
Filed under astronomy, space radiation.
Part 3 of my series on space radiation is about the radiation itself. The term cosmic rays is generally used to describe this radiation. Unfortunately, as often happens, the term evolved before the nature of the phenomenon being studied was known, so it may not be the best term to use. Nonetheless, we are stuck […]
Cabeus A, not Cabeus
Published on 12 Sep 2009 at 8:05 pm.
5 Comments.
Filed under astronomy, moon.
For the last couple of months, I’ve been so busy that I have not had time to do much blogging. Then, I kept wondering what to start writing about. Recently, the LCROSS program announced their target crater on the Moon: Cabeus A. That gave me an idea for what to post about.
First of all, I […]
A dark spot on Jupiter
Published on 29 Jul 2009 at 11:48 pm.
2 Comments.
Filed under Jupiter, astronomy, observing.
Amateur astronomer Anthony Wesley took an image of Jupiter on July 19 showing a dark spot on the planet. The spot looked remarkably like the sort of impact features left when Comet Shoemaker-Levy 9 hit Jupiter in July 1994. In fact, a lot of people very quickly announced that this was another impact on […]
Aphelion, 2009
Published on 4 Jul 2009 at 1:17 pm.
1 Comment.
Filed under astronomy, physics.
Last night, Earth reached the farthest point in its orbit from the Sun. This distance is called the aphelion of Earth’s orbit. The exact distance varies a bit from year to year due to perturbations in Earth’s orbit from the other planets, but it doesn’t vary by very much. We were just under 152,100,000 kilometers […]
Optical Coatings
Published on 7 Apr 2009 at 4:17 pm.
4 Comments.
Filed under astronomy, physics.
When you buy binoculars, eyepieces, or telescopes, you often run into terms such as coated optics, multi-coated optics, or fully coated optics. To the uninformed, these all sound the same. It seems like just a different choice of words to describe the same thing. Unfortunately, sometimes the sales people behind the counter […]
Two More Co-Orbitals of Earth
Published on 27 Jan 2009 at 4:25 pm.
14 Comments.
Filed under Earth, asteroids, astronomy.
In my last post, I wrote about the asteroid 2009 BD, which has an orbit very nearly that of Earth’s. But, it is not Earth’s only orbital companion. I know of more than a half dozen asteroids whose orbits would be considered co-orbital with Earth. The two that I want to talk […]
