LYRID METEOR UPDATE: The Lyrid meteor shower peaked last night, April 21-22, as Earth passed through a stream of debris from Comet Thatcher. Bright moonlight sharply reduced the shower's visibility, decreasing meteor rates 10-fold from ~20 to only ~2 per hour. NASA's network of all-sky meteor cameras detected 5 Lyrid fireballs over the USA. These were the brightest meteors of the night, visible only because of their moon-like luminosity. [sky map] [photo gallery]
RECTANGULAR SUNSET: Everyone knows the sun is round. But when Liselotte Kahns photographed the sunset from Vendsyssel, Denmark on April 19th, the shape was definitely rectangular:
"This is a mock mirage sunset caused by temperature inversions," explains atmospheric optics expert Les Cowley. "These inversions can slice the sun, producing multiple images with some rising and some descending. Sometimes they look rectangular."
There's a more extreme version of this called the "Novaya Zemlya" mirage. Observed near the poles, severe temperature inversions can channel the sun's rays all the way around the curvature of the Earth. "In the Novaya Zemlya mirage, the sun looks rectangular and rises minutes early or sets many minutes late," says Cowley. "Liselotte's mirage is not a Novaya Zemlya," but it's the next best thing outside the Arctic Circle.
Realtime Space Weather Photo Gallery
SOLAR WIND, INCOMING: A southern hole in the sun's atmosphere is facing Earth and spewing a stream of solar wind in our direction. NASA's Solar Dynamics Observatory took this extreme ultraviolet image of the opening on April 21st:
This is a "coronal hole," a region where magnetic fields peel back and allow solar wind to escape. The gaseous material is emerging at speeds near 500 km/s (1.1 million mph), and should reach Earth on April 23-24. Minor geomagnetic unrest and polar auroras are possible on those dates. Aurora Alerts: SMS Text.
MOTHER'S DAY IS ONLY 3 WEEKS AWAY! Approximately once a week, the students of Earth to Sky Calculus launch a cosmic ray balloon. To help pay their helium bill, they've flown a payload of Northern Light pendants to the edge of space. This one reached an altitude 109,908 feet above Earth's surface:
Northern Lights pendants make great Mother's Day gifts, and you can have one for $99.95. Each pendant comes with a greeting card showing the item in flight and telling the story of its journey to the edge of space. All sales support the Earth to Sky Calculus cosmic ray ballooning program and hands-on STEM research.
Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education