October! The month of occult science!
No, I don’t want to discuss witches flying up in the air. But in observational astronomy, we have events called occultations (meaning “being hidden”), in which the moon, a planet or an asteroid comes between us and a star and blocks out the light. We can learn a lot by timing these eclipses of distant suns.
I got my own introduction to astronomical research by observing lunar occultations as a teenage amateur astronomer. I had built a couple telescopes, and my dad and I built an observatory on the roof of our house. I would sometimes get up in the middle of the night, climb the ladder up to the observatory, slide its gently sloped roof panels apart, and point my telescope to a star about to be occulted by the moon. I would get the old Hallicraters shortwave radio tuned to the time announcements from WWV (the U.S. National Institute of Standards and Technology station) and start my stopwatch. When the star disappeared – and it’s the most instantaneous turning off of a light you have ever seen – I would stop the watch, determining the event time.
I reported my timings to the Royal Observatory in England: The results were used to monitor the ever-changing orbit of the moon. The moon’s orbit was of great interest to NASA, which was about to land astronauts there.
Monday night, I will be observing the occultation of an obscure star that is 100 times fainter than the faintest you can see with your naked eye. But tonight, the occulter is not the moon but an asteroid named Vundtia, a rock about 60 miles in diameter. The star will wink out for, at most, about four seconds.
Having since turned pro, and with advances in technology, I’ll remotely connect to our observatory and control the telescope and camera from home. I will start the telescope drifting at a slow rate and take a long exposure centered on the predicted time of the event. This motion will paint the target star and its neighbors as streaks down the image. If I get the event, there will be a gap in the target star’s streak. My results and the results of several more observers at different distances from the asteroid shadow’s centerline will be combined to reveal the size and shape of the asteroid.s
This is an early event, at about 8:20 p.m. If you want to know if I got it, you can follow my “occult” science on Twitter ( @DanielCaton). And a witch’s brew of information on the occultation can be found at www.upintheair.info.
Daniel B. Caton is a physics and astronomy professor and director of observatories at Appalachian State University. Email: email@example.com.
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