Ice and Stone
This Week in History: December 27-31
DECEMBER 27, 1984: A team of American meteorite hunters finds the meteorite ALH 84001 in the Allan Hills region of Antarctica. This meteorite was found to have come from Mars, and in 1996 a team led by NASA scientist David McKay reported the presence of possible “microfossils” and other evidence of potential biological activity within …
Comet of the Week: Kohoutek 1973f
Perihelion: 1973 December 28.43, q = 0.142 AU This comet’s story starts about two years before its actual discovery when Brian Marsden (at the IAU’s Central Bureau for Astronomical Telegrams) performed some orbital calculations of the long-lost periodic Comet 3D/Biela (a previous “Comet of the Week”). The comet had not been seen since the mid-19th Century …
Special Topic: Putting It All Together
When I first began reading about the solar system as an elementary school student in the mid-1960s, it seemed to be a much simpler place than what we know today. There was the sun, around which orbited nine planets; some of these planets had moons, Jupiter having the most with 12. Between Mars and …
This Week in History: December 20-26
DECEMBER 20, 1900: Michel Giacobini at Nice Observatory in France discovers the comet now known as Comet 21P/Giacobini-Zinner. This is the parent comet of the Draconid meteor shower and is also the first comet to be visited by a spacecraft; it is a previous “Comet of the Week.” DECEMBER 21, 1969: Comet Tago-Sato-Kosaka 1969g passes …
Comet of the Week: Lovejoy C/2011 W3
Perihelion: 2011 December 16.08, q = 0.006 AU In the “Special Topics” presentation on Kreutz sungrazers eight weeks ago I mentioned that in 2007 Zdenek Sekanina and Paul Chodas published a paper wherein they predicted that a new “cluster” of sungrazers should be arriving within the next few decades, with “its earliest member possibly just several …
Special Topic: Formation of the Planets
Ever since humankind began to discern the overall structure of the solar system a few centuries ago, i.e., that the sun basically resides in the center and the planets orbit around it, this has brought forth questions, for example, how did the planets, and the solar system as a whole, form? A second question would …