01/09/2012 – Ephemeris – Ephemeris on the Internet
Monday, January 9th. The sun will rise at 8:18. It’ll be up for 9 hours and 2 minutes, setting at 5:20. The moon, at full today, will rise at 6:09 this evening.
Although radio is a wonderful medium, it could help with a little visual assist from time to time. I have a website and a blog to help visualize the night sky and events. The website at ephemeris.bjmoler.org is updated monthly with that months sky events with illustrations and animations, while the Ephemeris Blog is updated daily at bobmoler.wordpress.com. By the way Moler is spelled simply M-O-L-E-R, no extra letters. Searching my name in Google will display these sites near the top. The blog has transcripts of the programs and best of all illustrations of the program topics, something I can’t do here. The nice thing about blogs is they are searchable by topic. I also have links to other sites if interest and free astronomical software.
* Times, as always are for the Traverse City/Interlochen area of Michigan.
Note:
These blog entries are scheduled to be released at 6 a.m. on the air date. The mp3s of the programs are available, generally a week at a time on the Ephemeris website.
Bob Moler's Ephemeris Blog 
Far to the North of the ecliptic, in the constellation of Perseus, is the most celebrated binary star in the night sky. Algol ( Per or Beta Persei) is named after the Arabic ‘Al Ghul’ meaning ‘the demon’. It marks the eye of a Gorgon named Medusa (from Greek mythology) which the hero Perseus slain; ancient star maps picture him holding Medusa’s severed head. Algol is a type of variable called an eclipsing binary, meaning that its brightness change is caused by a large, darker companion star (Algol B) which is in orbit about the brighter (and smaller) primary star (Algol A). When Algol B passes in front of Algol A (as viewed from the Earth) the overall magnitude of Algol reduces. When they are separated, the combined light of the two stars make Algol appear brighter. Algol’s magnitude varies from 2.1 to 3.4 in a period of 2 days, 20 hours and 49 minutes. For all except 10 hours of this period Algol shines at maximum brightness. The fall in brightness takes place in just 5 hours, as the dark companion moves in front of the primary star. Following minimum, Algol returns to its original brightness after a further 5 hours. The changing brightness of Algol can be observed by the naked-eye alone, hence it has often been called the ‘winking star’. Its fainter component, however, cannot be resolved in telescopes since it orbits the primary at a distance of just 10.5 million kms (6.5 million miles). The dates and times at which Algol reaches its minimum (the ‘Minima of Algol’) can be found on various websites, eg. Sky & Telescope . Algol is positioned 93 light years from Earth and in the 1970s was one of the first stars discovered to be a source of X-ray emissions.