My Dark Sky

Transits are everywhere in our universe – transits of Mercury or Venus across the Sun, transits of moons across their parent planet, transits of exoplanets across their parent stars.

But the transit I’m going to show you below is nothing we have ever seen before.

Click here for higher resolution.
This is the transit of our Moon across the globe of our home planet! During a full Earth rotation, images obtained by the NASA’s EPOXI spacecraft some 50 million km away at a 15-minute interval were combined to make a colour video. From the video, we see the Moon enter the scene, transits Earth, and then leaves the scene.

This is not the first time we saw our planet and Moon together through the eyes of spacecraft, but this is the first time we were to see them in motion, and to actually see the Moon slowly moves in front of us, and to think back how far we have advance since the first satellite was launched, and to remind us how beautiful and unique our planet is, really make me gasp in awe.

The video above is produced using an infrared-green-blue filter to make the land masses much more visible because plants reflect more strongly in the near-infrared. There is another version of the video which uses a red-green-blue filter, showing how it’ll appear to a human eye.

EPOXI is a new mission using an old spacecraft. The spacecraft is previously used for the Deep Impact Mission, which hurled a 370-kg copper impactor at Comet 9P/Tempel back in July 2005. After it completed its prime mission, proposals were made to utilise the spacecraft further for other purpose – don’t waste, recycle…

So now the spacecraft has not one, but two new extended missions. And these are two very different projects. One is the Deep Impact Extended Investigation (DIXI) of comets where it will observe comet 103P/Hartley 2 during a close flyby in November 2010. The other half is called Extrasolar Planet Observation and Characterisation (EPOCh), where it will observe stars with known transiting giant planets.

Combine EPOCh and DIXI and we have EPOXI.

The video above is going to be useful to help scientists develop techniques to study alien worlds.

“Making a video of Earth from so far away helps the search for other life-bearing planets in the Universe by giving insights into how a distant, Earth-like alien world would appear to us,” said University of Maryland astronomer Michael A’Hearn, principal investigator for the EPOXI mission.

Once in a while, we’ll have to look back at ourselves, so that we can understand others better…

Source: NASA Mission News

~ by thChieh on July 19, 2008.

Posted in Earth, Moon
Tags: EPOXI