Wednesday, August 29, 2007

Eclipse: Three A.M. On a School Night?

What? Three A.M. on a school night? Meshuggeneh!

Yep. We got up at that time, early Tuesday morning. We could have gotten up earlier to watch the pennumbral phase, but we thought some rest might be nice. After all, Bruce had to go to work and I had two classes on Tuesday.

So we chose to get up close to the beginning of totality during the total lunar eclipse, visible from 5 continents early yesterday morning.

At three A.M., the moon was somewhat obscured by clouds, but by about 3:30 AM, when the eclipse was just beginning totality, we could see the moon--deep red in the shadow of the earth.

So we had our science "lab" there on the back patio before the birds even thought of stirring. We defined the phases of a lunar eclipse and we talked about how the shadow of the earth always projects into to space, opposite of where the sun is shining on earth. A lunar eclipse happens when the moon happens to be inside the bounds of the shadow. Wed talked about why a lunar eclipse happens more often near the equinoxes--it has to do with the tilt of the earth and where we see the moon relative to the sun with respect to that tilt of 23' 27" from the plane of the ecliptic. We talked about how people in the past have interpreted lunar eclipses--and indeed solar eclipses. We used the Astronimical Calendar to find the times of each phase of the eclipse, and we discussed what Universal Time is and how to calculate where we are in time (Greenwich -6 during Daylight Savings time) in relation to UT.

Toward dawn, when the moon was moving out of the earth's shadow, we took some pictures. We talked about why we could see the eclipse through the binoculars at 3:30 AM, but not with the camera lense.

N. guessed that the binoculars had a greater magnification. But that's not true. Actually, the binoculars we were using magnified by 12X wheras when the zoom was full-strenth on the camera, it has a magnification of 15X.

The most important aspect of viewing astronomical objects is the apeture of the lense--that is the diameter of it--because as size increases, the light-gathering ability of the lense increases. The more light the lense can gather, the more you can see. The apeture of the camera lense is small compared to the apeture of the binoculars. So, to take pictures, we had to wait until there was more light in the sky. Successful pictures happened as the earth turned toward the dawn.

We learned quite a lot really. To review:
  • the mechanics of a lunar eclipse (astronomy)
  • the seasonal effect on the moon entering the earth's shadow (astronomy, earth science)
  • where the moon appears in the sky related to time, lunar phase and earth season (astronomy, earth science)
  • the phases of a lunar eclipse (astronomy)
  • the relative importance of apeture v. magnification in astronomical viewing (optics)
  • the cultural meanings of lunar eclipses (anthropology)

And we got to share some time out in the dark while most of our part of the world was sleeping. We noticed that the dawn breeze actually brings the temperature down just at sunrise. We noticed that some animals are out hunting at night.

When the sun rose the moon was just setting, as happens during the full moon, and this day it settled into the rosy western horizon with a tiny bite out of it.

Beautiful. And that was the last of our learning. We learned again that all times of the day and night have their own beauty.


Phil Outsource said...

You are lucky that you are able to witness it. I wasn't able to see it in our place, its raining during that time. I hope there will be a next time soon with clear skies. I really wanted to see it.

Magpie Ima said...

We had a perfect view here in Oregon. My two boys simply stayed up and waited and I woke up my daughter so she could see "The Oblix", as she called it.