Info from the link for those who want to see it directly: _____________ What will happen on March 20, 2014 around 2:06 am EDT, and why is it so special? The ~45-mile-wide asteroid Erigone will pass in front of a very bright star (Regulus). The star is easily visible to the naked eye from all but the most light-polluted areas. Since the asteroid is much too small and dark to be visible, for people standing in the path of the asteroid’s shadow one of the brightest stars in the sky will simply seem to disappear from the sky for up to 14 seconds. Astronomers have been predicting occultations of stars by asteroids for almost 40 years, and Regulus is the brightest star to ever be predicted to be occulted by a sizeable asteroid anywhere in the USA. So it really is likely to be a once-in-a-lifetime experience for most who live within the path. Since Regulus is about 4 million times farther away from us than the asteroid, you can imagine that many factors need to be properly aligned for this event to be visible from our planet. First the asteroid must pass in front of the star. Then the shadow of the asteroid must fall on Earth in an area where it is night, and of course the sky must be clear (frequently not the case in March in the Northeast part of the USA). Next the orbit of the asteroid and the location of the star must be known with sufficient accuracy for the prediction of where on Earth the shadow will pass to be made with some reasonable amount of certainty. (For example, a prediction that said the shadow would pass “somewhere over the continental USA on March 20th” would probably not be worth getting out of bed for!) IOTA makes every effort to use all available information from NASA and other sources to make our predictions as accurate as possible. The prediction for Erigone and Regulus is expected to be extremely accurate. For many people, viewing the occultation of Regulus may be a once-in-a-lifetime event, similar to a solar eclipse but of a more subtle nature. Regulus is easy to see in the sky “naked eye” and you have probably seen it there many times without even knowing it. We usually have to wait many years before any particular asteroid passes in front of a star bright enough to easily be seen without a telescope. The temporary disappearance of a star as bright as Regulus behind an all-but-invisible asteroid is thus a rare and beautiful occurrence. Here is a link to the IOTA path prediction for the event: Erigone/Regulus Path Prediction Here is a link to a google map version of the IOTA path prediction: Erigone/Regulus Path Google Map . You may drag and zoom on this map as you would on any Google map. The map shows a green line, two blue lines and two red lines. If the asteroid’s shadow followed its most likely central path (the green line) exactly, it’s edges would follow the two blue lines. However since there is some uncertainty in where the actual central path will go, the red lines identify a slightly larger zone in which there is a 66% probability that the edges of the shadow will pass inside (the 1-sigma uncertainty zone).
Posted on: Mon, 17 Mar 2014 18:10:49 +0000
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