anonsally:

llamapunk:

lies:

dendroica:

andromeda1023:

livefromearth:

Tonight’s a great night to look up. Starting at 2AM EDT and peaking from 3am to 4:30, there will be a lunar eclipse visible from all of North America. To make things better, Mars is currently very close to Earth, making it the brightest object in the night sky.

If you’re lucky enough to be viewing tonight’s events from Central Florida, Space-X will be launching a Dragon 9 capsule to the ISS at 4:58PM EDT – adding a little extra something to the sky.

See you in the stars.

(via

TumbleOn

)

Unfortunately it will be overcast (and eventually rainy) here, but I’m reblogging for people with clearer skies.

Yo, Sally! :-)

10:47pm PDT: Husband reports (from living room) that the edge of the moon has disappeared.

Confirmed from my balcony!

On a side note, I don’t quite like this infographic, because I doubt that the penumbra is the exact width of the moon. This makes it look like the beginning of the partial eclipse (second contact) coincides with the first moment when entire moon is inside the penumbra. Is that actually the case? This image seems to imply not. But if we ignore the penumbra, this is a great diagram.

I suspect this graphic is more or less accurate, while that one you link to is very idealized and not to scale.

That the width of the penumbra matches the width of the moon isn’t a coincidence. It’s just another way of expressing what the penumbra is: The part of the eclipse during which an observer on the moon would see the sun as partly, but not completely, eclipsed by the earth. That is, as the moon enters the earth’s shadow, it must travel exactly one moon-width to go from first entering the shadow to being entirely within it.

An interesting (but unrelated) coincidence is that the moon as viewed from earth is the same size in the sky as the sun (about 1/2 degree). That’s the reason the moon almost exactly covers the sun’s disk during a total solar eclipse. The earth viewed from the moon is substantially larger in the sky (about 2 degrees) which is why the region of totality (the earth’s umbra) in this diagram is substantially larger than the moon’s disk.

Reposted from http://ift.tt/1kXo1VC.

This entry was posted by jbc on Tuesday, April 15th, 2014 at 7:43 am and is filed under Tumblr. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.