THE NEXT GEOMAGNETIC STORM: Earth is exiting a stream of solar wind that sparked bright auroras over the Arctic Circle on Valentine's Day. Another stream is expected to arrive on Feb. 19th, bringing with it a chance of G1-class geomagnetic storms. The gaseous material is flowing from a canyon-shaped hole in the sun's atmosphere. Aurora Alerts: SMS text, email.
THE BRIGHTEST STAR IN THE SKY IS ABOUT TO VANISH: On Monday night, Feb. 18th, the brightest star in the sky will disappear. It's a rare eclipse of Sirius by asteroid 4388 Jürgenstock. As recently as two days ago, specialists thought the eclipse would be visible in a narrow corridor cutting across the central USA. New calculations, however, suggest a different path:
Sirius's shadow will cross southern parts of Chile and Argentina, Central America and the Caribbean. This will happen on Feb. 18th between 09:11 pm PST and 09:27 pm PST.
According to David Dunham of the International Occultation Timing Association, the eclipse could last for as much as 1.8 seconds, with Sirius fading to minimum brightness for 0.2 seconds of that time. The angular diameter of Sirius is 0.006 arcseconds. Asteroid Jürgenstock is just a little wider: 0.007 arcseconds, so theoretically Sirius should be completely blocked. "But the asteroid may be a little larger or smaller than predicted, and it's likely to be irregularly-shaped, so there is a good chance that even at the center, the star will not completely disappear," notes Dunham.
Named after Venezuelan astrometrist Jürgen Stock, asteroid 4388 Jürgenstock orbits the sun in the inner regions of the asteroid belt between Mars and Jupiter. It is approximately 5 kilometers (3.1 miles) in diameter. Video recordings of the eclipse could help trace the shape of the distant space rock.
Resources: finder charts, observing tips, eclipse home page.
Realtime Space Weather Photo Gallery
SPACE WEATHER ALERTS: Spaceweather.com is proud to announce our new and improved space weather alert system. Sign up now and you'll never miss another solar storm in 2019. Subscribers receive instant text messages when there are solar flares, geomagnetic storms, and CMEs about to strike Earth. And if you sign up for the PRO PLAN, you'll receive a type of alert available no where else--"Magnetic Crack" alerts. Keep reading after the graphic to learn more:
PRO PLAN subscribers get a text message whenever a crack is opening in Earth's magnetosphere. Magnetic cracks are caused by south-pointing magnetic fields ("BsubZ") in the solar wind, which partially cancel Earth's magnetic defenses. Solar wind pours in through these cracks to fuel bright auroras and geomagnetic storms. Veteran aurora chasers know that watching "BsubZ" is the best way to anticipate geomagnetic activity. Now your cell phone can do this job for you, alerting you when cracks are forming in the invisible magnetic field overhead.
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