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Home / Science / A 5km long asteroid can briefly obscure the brightest star in the night sky

A 5km long asteroid can briefly obscure the brightest star in the night sky



  The impression of an artist shows the binary star system of Sirius A and his tiny blue fellow, Sirius B.
Enlarge / The impression of an artist showing the binary star system of Sirius A and his faint blue companion , Sirius B.

NASA, ESA and G. Bacon

Sirius, a binary system, is the brightest star in the night sky. The larger of the two stars, Sirius A, is about 25 times brighter than the Sun, and Sirius is relatively close to less than 9 light-years away from our solar system.

On Monday night, for some areas in the South and Central America as well as the Caribbean, Sirius will likely disappear for a short time. This happens when a small asteroid passes in front of the star and cloaks it for up to 1.6 seconds, according to the International Occultation Timing Association. (Yes, the acronym is IOTA.)

In this case, the asteroid 4388 Jürgenstock has an apparent diameter that is only an iota larger than Sirius. The angular diameter of the asteroid is about 0.007 arc seconds (one arc second is 1/600 of the night sky), while the angled diameter of Sirius is 0.006 arc seconds. When the asteroid passes in front of Sirius, the star is briefly muted, perhaps completely, before lightening quickly. Sirius seems to blink slowly once.

  Sirius covering path on Monday evening. "src =" https://cdn.arstechnica.net/wp-content/uploads/2019/02/9igr821g9w.jpg "width =" 820 "height =" 585

Covering path from Sirius on Monday night.

International Occultation Timing Association

Unfortunately, the path for this event is mostly over water. Based on maps from IOTA, occultation appears over clippings from Argentina and Chile, Panama, the head of Haiti and possibly Turks and Caicos. There remains a slight uncertainty in the timing that is expected to begin along its journey, which starts at 05:11 UTC and ends on Tuesday, February 19, at 05:26 UTC.

With a diameter of 4.7 km asteroid belt object was discovered in 1964 by an astronomer who – you guessed it – Jürgen Stock. This covering should give astronomers a rare opportunity to better characterize the dimensions of the asteroid. It is likely to have an irregular shape and further contribute to the uncertainty of how far it will block the light from Sirius.

  Path of Sirius cover on Monday night. "Src =" https://cdn.arstechnica.net/wp-content/uploads/2019/02/cwerdv9svr.jpg "width =" 820 "height =" 585 [19659008PfadderSiriusCoveringinMondayNight</p>
<p>  International Occultation Timing Association [19659014] Because of its exceptional brightness in the sky, Sirius has long held a significant place in many cultures, with more than four dozen known names. The commonly used name Sirius has Greek origin, which means "glowing". </p>
<p>  The star may also play a significant role in future exploration, as Sirius is a good candidate for the first interstellar solar sail missions because of its luminosity. The stellar brightness would help the solar sailboat slow itself down as it approached the star system. However, there are no confirmed planets around either star. </p>
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