Sirius, a two-star system and the brightest object in the night sky, will disappear briefly for part of the Earth on Monday night.
In an event called occultation – when an object in space blocks another's light behind it – a small asteroid called (4388) Jürgenstock slips in front of the star for a fraction of second and, in the manner of an eclipse, briefly attenuate or even disappear.
"This unusual occultation of the brightest star in the night sky will occur around 10:30 pm, Monday evening, Feb. 18, in the evening," according to a message from Bill Merline of the Southwest Research Institute and David Dunham of KinetX Aerospace on the pages. occultation of the website run by astronomers.
Here is where you can see Sirius' occultation by the Jürgenstock asteroid and how your observation of the event could actually help astronomers.
Where and when to see Sirius disappear
To understand where and when the occultation will be visible, it is useful to think of a moving ball blocking a light bulb, which would draw a moving shadow on a wall.
Another suitable comparison is a solar eclipse, when the moon blocks the sunlight.
Read more: NASA recorded the international space station in flight in front of the solar eclipse
Similarly, Jürgenstock – an asteroid 3 km wide – will fly in front of Sirius and block some of its light. This will make a small blurry shadow on the Earth in 21 minutes.
This shade of occultation, which Sky & Telescope first spoke to us, will begin in Antarctica, will turn around the South Continent, and then head north across the Southern Ocean and back. Pacific Ocean.
After Antarctica, the first terrestrial site to see the occultation should be the southern tip of Baja California in Mexico, around 22:28. STDs.
The next stop will be the US cities of Las Cruces, New Mexico, and El Paso, Texas. These southern locations will have a chance to watch the event around 10:30 pm. STDs.
Then, around 10:31 pm EST (23:31 CST), Denver, Colorado and parts of western Nebraska will have the opportunity to see it.
A series of maps created by Merline and Dunham shows exactly where night watchers can try to see the event, weather permitting. The map below shows the general trajectory and timing of visibility in Central America and North America.
Astronomers note that their predictions, although accurate, are not perfect. Sirius is too clear for spacecraft to determine its exact movement and position in space. The map therefore indicates a probable visibility range of approximately 130 miles. Even at the level of the central line, there is only 7% chance to observe a complete occultation by the decrease of Sirus.
"If you have the chance to see the path go through your position, the star will fade over a period of several tenths of a second, probably will not disappear completely, then regain full brightness for several tens of seconds, "wrote the astronomers. "But it could be a slight drop in brightness for maybe only half a second, if you're by the wayside."
If you plan to try to see occultation, Merline and Dunham recommend reading the basics of viewing such an event at the International Occultation Timing Association.
For their part, Merline and Dunham plan to travel to Las Cruces for an early US preview – and ask everyone for help to attend this event.
"If we really observe the occultation, it could be useful, to define the position of Sirius with a much greater precision than we currently know," they said.
If you are ready to help, read the astronomers' complete instructions on their occultation.