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Posts Tagged ‘Sun’

07/06/2012 – Ephemeris – Sun and planet viewing tonight

July 6, 2012 Comments off

Ephemeris for Friday, July 6th.  Today the sun will be up for 15 hours and 25 minutes, setting at 9:29.   The moon, 3 days past full, will rise at 11:06 this evening.  Tomorrow the sun will rise at 6:05.

This evening the Grand Traverse Astronomical Society will hold its monthly meeting at the Northwestern Michigan College’s Rogers Observatory at 8 p.m.  This meeting will be devoted to viewing the sun through the society’s new solar telescope.  After that starting at 9 p.m. Will be a star party.  For both events, the public is welcome.  The tiny planet Mars and the ringed planet Saturn will be visible as will a number of binary stars and brighter wonders of the heavens as the skies darken.  Mercury is now receded toward the sun so is not visible.  For the rest of the abbreviated planet report this week:  A note for early risers that Jupiter and Venus make a fine sight low in the east northeast in the morning after 5 a.m.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

05/17/2012 – Ephemeris – A safe way to view this Sunday’s solar eclipse

May 17, 2012 Comments off

Ephemeris for Thursday, May 17th.  Today the sun will be up for 14 hours and 54 minutes, setting at 9:06.   The moon, 3 days before new, will rise at 4:44 tomorrow morning.  Tomorrow the sun will rise at 6:10.

Lets talk about a safe viewing method for viewing the sun, for Sunday’s solar eclipse, which starts about 8:19 p.m.  Never look directly at the sun, eclipse or no.  Pinhole projection is a cool method to watch the eclipse without hurting your eyes.  Get a cardboard box, the longer the better.  On one narrow end poke a hole, no larger than an 8th of an inch in diameter.  You can poke several holes an inch apart of varying sizes to get multiple images of the sun of different brightnesses and sharpness.  On the inside of the other end paste a piece of white paper.  Point the holey end at the sun and its image will be projected on the white sheet.  Tomorrow I’ll tell you where to go to get the best view of the eclipse.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

There’s more information on my blog here.

Pinhole projection:

Pinhole Projection of the sun.

Pinhole Projection of the sun.

Note the brightness of the sun was augmented and moon shadow added to give an idea what the solar image would look like.  The box is 39 inches long.  it gives an image 1/3 of an inch in diameter.

12/15/11 – Ephemeris – Comet Lovejoy will skim past the sun today

December 15, 2011 3 comments

Thursday, December 15th.  The sun will rise at 8:12.  It’ll be up for 8 hours and 50 minutes, setting at 5:02.   The moon, 2 days before last quarter, will rise at 10:39 this evening.

Today Comet Lovejoy will pass 100,000 miles above the surface of the sun.  The sun is 865,000 miles in diameter, so that’s very close.  Will the comet survive?  Will it break into multiple pieces? Or will it evaporate in the sun’s intense heat?  To get the latest news on the internet go to Spaceweather,com or space.com.  For first hand information google SOHO  NASA.  Look for real time images.  LASCO C3 and C2 are the views you want.  These are near white light views with the sun’s face blocked out so the solar corona is visible.  The C2 view is closer in than the C3 view.  The comet will move from the lower left to upper right. And will go behind the occulting disk that hides the sun. The comet’s tail should be quite long.

* Times, as always are for the Traverse City/Interlochen area of Michigan.

Update 6:09 a.m.

Comet Lovejoy at 9:30 UT or 2:23 a.m. EST. Courtesy of ESA, NASA, LASCO Team.

Comet Lovejoy at 9:30 UT or 2:23 a.m. EST. Courtesy of ESA, NASA, LASCO Team.

Click image to enlarge.

08/16/11 – Ephemeris – Solar conjunctions today of Mercury and Venus

August 16, 2011 Comments off

Tuesday, August 16th.  The sun rises at 6:45.  It’ll be up for 14 hours and 0 minutes, setting at 8:46.   The moon, 3 days past full, will rise at 9:38 this evening.

Today we have an interesting coincidence.  Both Venus and Mercury will be in conjunction with the sun.  Astrologers may make a big deal out of it but this time astronomers won’t.  A conjunction means that two solar system bodies are just north and south of each other.  At 8:07 this morning Venus will be just north of the sun in superior conjunction.  That is it is beyond the sun.  And at 9:03 this evening Mercury will be somewhat south of the sun in inferior conjunction.  Thai is it is between the earth and the sun.   Mercury will be going into our morning sky, while Venus will begin to appear in the evening sky later this fall.  But the coolest thing of all will be Venus’ next inferior conjunction June 6th, 2012.  It will cross the face of the sun in a rare transit.

* Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

05/10/11 – Ephemeris – The Ancient Greeks and measuring the distance to the sun

May 10, 2011 1 comment

Tuesday, May 10th.  The sun rises at 6:20.  It’ll be up for 14 hours and 36 minutes, setting at 8:57.   The moon, at first quarter today, will set at 2:46 tomorrow morning.

The ancient Greek astronomers had great success in actually calculating the distance to the moon.  They came up with 60 earth radii.  Yes, they knew the earth was round and even measured its circumference to great accuracy.  The distance they got for the moon lies within the range of the actual moon’s distance.  They next tried to measure the distance from the sun.  To do this, they tried to observe the moon and the sun at the exact time the moon was at first quarter.  At this time the earth, sun and moon make a right triangle.  Theoretically the actual angle between the sun and the moon would give the distance to the sun.  The answer they got was that the sun was 20 times the moon’s distance.  That’s way short, the sun is 400 times the moon’s distance away.

* Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

How the ancient Greeks tried to calculate the diatance to the sun.

How the ancient Greeks tried to calculate the distance to the sun.

To the right is my take on the Greek sun measuring experiment.  Using their guy Euclid and his geometry they knew that the sum of the angles of a triangle equal 180 degrees.

Having an exactly quarter moon, first or last, they knew the Sun-Moon-Earth angle was 90 degrees, so if they could measure the Sun-Earth-Moon angle from observation, they knew the other angle at the sun.

They had already calculated the moon’s distance, so they could calculate the other leg, the Sun-Moon distance using trigonometry.  The first trig tables were invented by Greek astronomer Hipparchus.

Ah yes, Trig tables.  I don’t suppose you kids use them anymore, with your electronic calculators.  Back in my high school days my calculator was a slide rule.  Sorry, old guy grousing.