Previous in Forum: Wanted: 5150 Steel 2.5" Round   Next in Forum: Cosmic Ray Shower Experimental Group - CSEG
Close
Close
Close
3 comments
Commentator

Join Date: Jan 2006
Location: On Top of the World
Posts: 79

See This Video of Lunar Transit of the Sun

03/13/2007 1:18 PM

From Science@Nasa comes an extraordinary video of a lunar eclipse of the sun.

__________________
Metaphors Be With You
Reply
Pathfinder Tags: dark current NASA solar eclipse STEREO-B sun
User-tagged by 1 user
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Anonymous Poster
#1

Re: See This Video of Lunar Transit of the Sun

03/14/2007 12:09 AM

That is a planet passing between the camera and the sun. Not the earths moon. Viewed from earth the moon almost exactly matches the size of the sun during a lunar eclipse.

Reply
Anonymous Poster
#2
In reply to #1

Re: See This Video of Lunar Transit of the Sun

03/14/2007 4:05 AM

It is not a transit viewed from Earth-but an Off-Earth view, hence the size difference.

From the transcript:

"The images have an alien quality," notes Guhathakurta. "It's not just the strange colors of the sun. Look at the size of the Moon; it's very odd." When we observe a lunar transit from Earth, the Moon appears to be the same size as the sun—a coincidence that produces intoxicatingly beautiful solar eclipses. The silhouette STEREO-B saw, on the other hand, was only a fraction of the sun's diameter. "It's like being in the wrong solar system."

The Moon seems small because of STEREO-B's location. The spacecraft circles the sun in an Earth-like orbit, but it lags behind Earth by one million miles. This means STEREO-B is 4.4 times further from the Moon than we are, and so the Moon looks 4.4 times smaller

Reply
Anonymous Poster
#3
In reply to #2

Re: See This Video of Lunar Transit of the Sun

03/14/2007 9:06 AM

Pretty cool video - I am confused by the angles though. The moon is obviously directly in between STEREO-B and the the sun. With the moon being about 240,000 miles from the earth, and the apparent size of the moon being about 1/5 the apparent size of the sun, it indicates that the distance of the ship to the moon is about 1,200,000 miles. The article states that STEREO-B lags behind the earth in it's orbit by about 1,000,000 miles, but this would never put the moon directly between the ship and the sun. The angles to me more indicate that they maneuvered the ship to be about 1,200,000 miles farther away from the sun, lagging only 240,000 miles behind the earth, so that they could see the moon pass in front of the ship as the moon is at a right angle to the earth-sun line.

They mention a maneuver to make this photo possible - perhaps the maneuver pushed the ship into a slightly elliptical orbit to move it out from the sun and closer to the earth? But as the ship moves farther from the sun, it will move slower than the earth, and not catch up... Sounds like an energy intensive maneuver.

Am I missing something?

Reply
Reply to Forum Thread 3 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Previous in Forum: Wanted: 5150 Steel 2.5" Round   Next in Forum: Cosmic Ray Shower Experimental Group - CSEG

Advertisement