COMET ATLAS IS BRIGHTENING FASTER THAN EXPECTED: Get ready for a wild ride. Comet ATLAS (C/2019 Y4) is plunging toward the sun and, if it doesn't fly apart first, it could become one of the brightest comets in years. Full Story.
EQUINOX AURORAS: A solar wind stream hit Earth's magnetic field on the vernal equinox. Perfect timing, because auroras love equinoxes. "What a night! Equinox auroras are the real deal," reports Rayann Elzein of Utsjoki, Finland, who took this picture on March 19th:
In addition to a spray of green auroras, a bright pink band split the sky. A pink-quinox aurora? "I think it might be STEVE," says Elzein. "That would be a first for me at such high latitude (70°N)."
STEVE is an aurora-like glow caused by hot ribbons of plasma flowing through Earth's magnetic field. It's always pink (or light purple) and shaped like the ribbon that causes it. STEVE normally appears at least 10 degrees south of the Arctic Circle. Recently, however, Arctic sky watchers have been seeing it, too. The habitat of STEVE may be widening.
Equinoxes are special because of the Russell-McPherron effect. At this time of year, the interplanetary magnetic field (IMF) can link up with Earth's magnetic field, prying open cracks. Solar wind flows through to spark auroras and more. Happy equinox! Aurora alerts: SMS Text.
Realtime Aurora Photo Gallery
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THE SIZE OF COMET ATLAS: No one knows how big the icy core of Comet ATLAS (C/2019 Y4) might be. Possibly, it's no wider than a few kilometers. One thing's for sure, the comet's atmosphere is huge. This picture from Hisayoshi Kato of Uchiyama, Nagano, Japan, shows that it is almost as wide as the full Moon:
"The comet is bigger and brighter compared to only 3 days before," says Kato. "Its green coma (atmosphere) is about 20 arcminutes in diameter." For comparison, the Moon is 30 arcminutes wide.
Combining this angular measurement with the comet's distance from Earth (1.1 AU) allows us to compute its physical size: Almost 1 million km wide. That's a big ball of gas, spacious enough to swallow a row of planets 4 Jupiters across. If Comet ATLAS ever becomes visible to the naked eye, it could be impressive indeed.
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MR. SPOCK BOBBLEHEAD IN THE STRATOSPHERE: If you would like to support the Earth to Sky Calculus cosmic ray ballooning program, there's a logical way to do it. Puchase this Mr. Spock collector's item. Here is the green-blooded science officer floating 32.2 km (112,200 ft) above Death Valley National Park in central California:
You can have him for $170.10. The price, in case you're wondering, is the serial number of the Enterprise, NCC1701, divided by 10. The students are selling Spock to buy more helium! He comes with a greeting card showing the high-quality resin bobblehead in flight and telling the story of his journey to the stratosphere and back again.
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