Archive
05/03/2012 – Ephemeris – Eclipse cycles
Ephemeris for Thursday, May 3rd. The sun rises at 6:29. It’ll be up for 14 hours and 21 minutes, setting at 8:50. The moon, 2 days before full, will set at 5:11 tomorrow morning.
Eclipses of the sun and moon were most terrifying events for the ancient and primitive peoples. The Chinese thought a dragon was devouring the sun would bang on gongs and shoot arrows into the air to drive the dragon away. It worked every time. Predicting these eclipses became an important matter for ancient astronomers. It was the Chaldeans several centuries before the common era that apparently discovered the interval at which like eclipses occur. The period of 18 year 11 and a third days is called the saros cycle. There are many saros cycles running at any one time. A saros series contains 71 or 72 eclipses, crossing the earth slowly from north to south or south to north. We’ll talk more about eclipses later this month.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
For more information check out Saros in Wikipedia
Saros 136 animation, Public Domain (official work for NASA by Fred Espenak)
Above is an animation of eclipse paths running south to north for saros 136.
05/01/2012 – Ephemeris – The May 20th Eclipse
Ephemeris for Tuesday, May 1st. The sun rises at 6:32. It’ll be up for 14 hours and 15 minutes, setting at 8:47. The moon, 2 days past first quarter, will set at 4:09 tomorrow morning.
(Note: The eclipse visible from most of the United States will be interrupted by sunset. See the Addendum for a link to NASA’s page on the eclipse.)
Let’s give you a heads up on the solar eclipse that will occur on the evening of May 20th. In northern lower Michigan we will see the tail end of the eclipse as the moon’s shadow leaves the face of the earth. The shadow will touch the earth in eastern Asia, cross the Pacific and into North America. This is an annular eclipse, meaning that the moon is too far away to completely cover the face of the sun, leaving a ring (or annulus) of bright sun around the moon at the very center of the eclipse. Some residents of northern California and southern Oregon to west Texas will be able to see this annulus. Your visual safety is paramount when viewing an eclipse and over the next two weeks I’ll be giving you tips on how to view the eclipse safely.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Here’s a NASA Acrobat file detailing the eclipse. http://eclipse.gsfc.nasa.gov/OH/OHfigures/OH2012-Fig01.pdf
Here’s the Eclipses of 2012 NASA page that links to the above page. It has useful links for those, unlike us are located in the southwestern United States.
04/30/2012 – Ephemeris – Preview May Skies
Ephemeris for Monday, April 30th. The sun rises at 6:33. It’ll be up for 14 hours and 13 minutes, setting at 8:46. The moon, 1 day past first quarter, will set at 3:41 tomorrow morning.
Tomorrow we’ll start the month when the promise of spring is finally fulfilled. Daylight hours in the Interlochen/Traverse City area will increase from 14 hours and 15 minutes tomorrow to 15 hours 19 minutes on the 31st. The altitude, or angle, of the sun above the southern horizon at local noon will ascend from 60 degrees today to 67 degrees at month’s end. The altitude of the sun in the Straits area will be a degree lower than that but your daylight will be a few minutes longer. Local apparent noon this month, when the sun passes due south, will be about 1:38 p.m. The big event of this month will be a partial eclipse of the sun on Sunday May 20th, where we’ll see about 45 minutes of the eclipse as the sun sets.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
12/30/11 – Ephemeris – The best 2012 astronomical events
Friday, December 30th. The sun will rise at 8:19. It’ll be up for 8 hours and 51 minutes, setting at 5:10. The moon, 2 days before first quarter, will set at 12:02 tomorrow morning.
Let’s look ahead at next year’s astronomical events for this last Ephemeris of 2011. What won’t happen will be the end of the world on December 21st. There is no planet Nibiru. The closest alignment of the sun at the winter solstice and the center of the galaxy was in 1997. What will happen is partial eclipse of the sun, or about a half hour of it, before sunset on May 20th. An extremely rare transit of Venus, that is the planet Venus will cross the face of the sun on June 5th for us. We’ll see about 3 hours of it before sunset that day. The sun will continue to be more active next year with more sunspots and more displays of the northern lights. It will also be a good year for the Perseid meteor shower of August and the Geminids of December.
* Times, as always are for the Traverse City/Interlochen area of Michigan.
Bob Moler's Ephemeris Blog 