Astronomy Essentials

Flash of light brighter than Venus? Could be first solar sail to orbit Earth

Tonight, you just might see a brilliant flash of light that far exceeds that of the sky’s brightest planets and stars. If not tonight, you might see it some night during the next several months.

This streak of light will probably only last for 5 to 10 seconds before retreating into the darkness of night.

Not a plane. Not a meteor. No ordinary satellite. This flash of light might be your glimpse of the first-ever solar sail, or light sail, to circle our planet – an innovative NASA craft that began orbiting Earth on January 21, 2011.

It’s called NanoSail-D2. In theory, it can flash from 10 to 100 times more light in your direction than the planet Venus, which is the 3rd brightest object to light up the sky after the sun and moon. So the light sail could be very bright! But for you to see it shine so brightly, the 100-square-foot sail would have to reflect sunlight directly to you.

Still, you might see a flash if you watch for it – especially if you explore the links below. Want to spot NanoSail-D2’s short-lived yet brilliant burst sometime? NanoSail-D2 flyby predictions are available from Heavens-Above, and CalSky.

Are you a photographer? You can try to snap a picture of NanoSail-D2 before it disappears into the night. If you get one, you can enter it into the solar sail photo contest sponsored by NASA and

NanoSail-D2 is expected to be circling the Earth until sometime in April or May 2011.

Here’s a video explaining more about the solar sail. Actually, this video was written for NanoSail-D2’s predecessor, NanoSail-D, which was lost in a launch failure aboard a Falcon 1 rocket on August 3, 2008.

The sail itself is beautiful, isn’t it? You can imagine it in orbit around Earth, reflecting the sun’s light – hopefully, some in your direction so you can see it flash.

So that’s how to see NanoSail-D2, the first solar sail to orbit Earth. If all works well, this grand experiment by NASA may enable the use of lighter and less expensive spacecraft in the future. The solar sail design may help prevent the buildup of future space junk, or even help eliminate the old space junk that is presently orbiting Earth.

Venus is the bright object up before dawn in February

February 7, 2011
Astronomy Essentials

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Bruce McClure

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