Archive
05/15/2012 – Ephemeris – Viewing prospects of Sunday’s solar eclipse viewed from northern lower Michigan
Ephemeris for Tuesday, May 15th. Today the sun will be up for 14 hours and 50 minutes, setting at 9:04. The moon, 3 days past last quarter, will rise at 3:51 tomorrow morning. Tomorrow the sun will rise at 6:13.
Sunday evening’s partial eclipse will begin within a minute of 8:19 p.m. for most locations in the IPR listening area. The sun will be only about a 7 degree angle above the horizon at that time. That’s slightly less than the width of your fist held at arm’s length. At sunset, at about 9:10 p.m., with the flat horizon of Lake Michigan about 50% of the sun will be covered. The farther inland you are, or east from the shore, the start of the eclipse will be about the same time, but sunset will be earlier one minute every 12 miles east you are. An obstructed horizon will make sunset earlier. Thursday and Friday I’ll have safe eclipse observing tips. Or go to my May 8th entry at bobmoler.wordpress.com for an illustrated entry.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
May 20, 2012 eclipse from northern Michigan just before sunset. Created using Stellarium.
05/14/2012 – Ephemeris – Next Sunday’s annular solar eclipse
Ephemeris for Monday, May 14th. Today the sun will be up for 14 hours and 47 minutes, setting at 9:03. The moon, 2 days past last quarter, will rise at 3:27 tomorrow morning. Tomorrow the sun will rise at 6:14. | This Sunday evening we will, clouds willing, be able to see a piece of a solar eclipse before the sun sets. In northwest lower Michigan, we’ll see about 50 minutes tops at the Lake Michigan shore. This eclipse is an annular eclipse, where the moon isn’t big enough to completely cover the sun leaving a ring or annulus. The area affected by the partial eclipse stretches from east Asia to North America, from the Arctic Ocean to the South Pacific. The path of where the annular phase can be seen, stretches from south China to Texas. In the United States the annular shadow will cross from southern Oregon, and northern California, to Texas at sunset. We’ll see the very end of the partial eclipse.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Eclipse map of the May 20, 2012 annular solar eclipse. Credit: NASA
05/11/2012 – Ephemeris – The bright star Spica
Ephemeris for Friday, May 11th. Today the sun will be up for 14 hours and 40 minutes, setting at 8:59. The moon, 1 day before last quarter, will rise at 2:09 tomorrow morning. Tomorrow the sun will rise at 6:17.
The bright blue star Spica can be found in the southeast as it gets dark now. It’s one of the fainter of the 21 first magnitude stars. It lies in the constellation of Virgo the virgin, and lies very close to the path of the sun, moon and planets in the sky. Saturn is just to the left of it this year. Spica is a binary star, whose brighter component is drawn into an ellipsoid by the tidal effect of the companion. They orbit each other in only 4 days. Spica is 260 light years away and over 3,000 times brighter than the sun. An Egyptian temple at Thebes was oriented to the setting point of Spica. The change in the setting point over time allowed the Greek astronomer Hipparchus to discover the precession of the equinoxes.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Saturn and Spica on May 11, 2012. Created using Stellarium.
05/10/2012 – Ephemeris – The Virgo Cluster (of galaxies)
Ephemeris for Thursday, May 10th. The sun rises at 6:19. It’ll be up for 14 hours and 38 minutes, setting at 8:58. The moon, 2 days before last quarter, will rise at 1:36 tomorrow morning.
The constellation Virgo which contains the bright star Spica and for last and this year the planet Saturn is in a sparse region of the sky as far as stars go. We are almost directly looking out the side of our Milky Way Galaxy. That milky band has been banished to the northern horizon. But while the stars may be few, we are also looking out past a gulf of 50 million light years to a great cluster of galaxies we call the Virgo Cluster. The galaxies here count into the thousands and overflow Virgo itself into Leo to the west, Coma Berenices to the north and Corvus to the south. I found that an 8 inch diameter telescope can pick up the brightest, but that may be my eyesight. Charles Messier spotted them over 200 years ago with a telescope less than three inches in diameter.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Brighter members of the Virgo Cluster. Created using Stellarium. Open circles are galaxies, circles with crosses are globular star clusters, outlying members of our Milky Way galaxy.
Click on image to enlarge.
05/09/2012 – Ephemeris – Where are the bright planets this week?
Ephemeris for Wednesday, May 9th. The sun rises at 6:21. It’ll be up for 14 hours and 36 minutes, setting at 8:57. The moon, 3 days before last quarter, will rise at 12:57 tomorrow morning.
Let’s see what’s happening with the bright planets for this week. Venus is high in the west as it gets dark. Enjoy it now, because it will be gone in 4 weeks. Venus will set at 12:09 a.m. in the west northwest. That’s 19 minutes earlier than last week, so it’s noticeable drawing closer to the sun. Venus is 35.9 million miles away and closing. It is a beautiful brilliant crescent in telescopes. Mars is high in the south in the evening with its unmistakable bright reddish color. It’s in the constellation Leo the lion now. It is 94 million miles from us and moving away. Mars will pass due south at 9:08 p.m. and will be setting in the west at 3:52 a.m. Saturn will be in the southeast just to the left of the bright star Spica. It will pass due south at 12:04 a.m.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Southern sky at 10 p.m. on May 9, 2012. Created using Stellarium.
05/08/2012 – Ephemeris – Observing Saturn’s Rings
Ephemeris for Tuesday, May 8th. The sun rises at 6:22. It’ll be up for 14 hours and 33 minutes, setting at 8:56. The moon, 3 days past full, will rise at 12:09 tomorrow morning.
The planet Saturn is a wonderful sight in telescopes now. In a little as 20 power a spotting scope with show Saturn’s rings, but may not distinctly separate the planet out. At 50 power the planet is easily separated from the rings. It you have a telescope with eyepieces of differing focal lengths and/or a Barlow lens that doubles the magnification of your eyepieces, you can experiment with using higher powers. I like a crisp image at lower powers rather than a fuzzy image at higher powers. Saturn’s rings are its best known feature. They are about 170 thousand miles wide and perhaps only a hundred feet thick. They aren’t solid but billions of small icy particles each orbiting Saturn at their own speed, and kept in line by collisions with its ring mates.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Image of Saturn created with Cartes di Ciel showing current ring tilt.
The rings as they appear from earth. The outside ring is the A ring. Then the dark Cassini’s Division, which is sometimes hard to spot. Then the broad and bright B ring. The inner C ring is hard to spot.
05/07/2012 – Ephemeris – The Crescent Venus
Ephemeris for Monday, May 7th. The sun rises at 6:23. It’ll be up for 14 hours and 31 minutes, setting at 8:54. The moon, 2 days past full, will rise at 11:10 this evening.
The planet Venus now is spectacular both to the unaided eye and through a telescope. To the eye Venus is the brilliant evening star in the west in the evening. In a telescope it appears as a bright crescent like the moon. This surprised some of the folks that came out to out star party last Friday. The dark side of Venus is the night side of the planet because Venus is now moving between us and the sun, so it’s shining mostly on the other side of the planet. This effect will get more pronounced as Venus becomes more in line with the earth and the sun over this month. When Venus crosses between the earth and the sun June 5th, our time it will actually pass in front of the sun, a rare transit of Venus that will start a little past 6 p.m. That evening.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
05/04/2012 – Ephemeris – My talk Friday with star party to follow
Ephemeris for Friday, May 4th. The sun rises at 6:27. It’ll be up for 14 hours and 23 minutes, setting at 8:51. The moon, 1 day before full, will set at 5:48 tomorrow morning.
Radio astronomy will be the topic of yours truly this evening at the Grand Traverse Astronomical Society’s monthly meeting at 8 p.m. at Northwestern Michigan College’s Rogers Observatory. This is a rescheduling of a talk that was scheduled for the first Friday in March when we had the big snow storm. Prompted by my recent tour of the National Radio Astronomy Observatory in Green Bank West Virginia, I’ll overview this window on the universe that opened up after World War II. Starting at 9 p.m. will be the monthly viewing night at the observatory. On tap if its clear will be the moon and the planets Venus, Mars and Saturn. The Observatory is located south of Traverse City on Birmley Road off either Garfield or Keystone roads.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
GBT: The Green Bank radio Telescope at The national Radio Astronomy Observatory, Green Bank WV.
Click image to enlarge.
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.
05/02/2012 – Ephemeris – Where are the bright planets this week?
Wednesday, May 2nd. The sun rises at 6:30. It’ll be up for 14 hours and 18 minutes, setting at 8:48. The moon, half way from first quarter to full, will set at 4:39 tomorrow morning.
Let’s see what’s happening with the bright planets for this week. Venus is high in the west as it gets dark. Enjoy it now, because it will be gone in 5 weeks. Venus will set at 12:28 a.m. in the west northwest. That’s 8 minutes earlier than last week, so it’s noticeable drawing closer to the sun. Venus is 40.1 million miles away and closing. It is a breautiful brilliant crescent in telescopes. Mars is high in the south in the evening with its unmistakable bright reddish color. It’s in the constellation Leo the lion now. It is 89 million miles from us and moving away. Mars will pass due south at 9:30 p.m. and will be setting in the west at 4:18 a.m. Saturn will be in the east southeast just to the left of the bright star Spica. It will pass due south at 12:33 a.m.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The stars and planets at 9:30 p.m. on May 2, 2012. Created using Stellarium.
