EXITING THE SOLAR WIND: Earth is beginning to exit a narrow stream of solar wind that arrived only a little more than 24 hours ago. NOAA forecasters say there is a 40% chance of G1-class geomagnetic storms on Nov. 22nd, decreasing to 20% on Nov. 23rd. Arctic sky watchers should remain alert for auroras tonight before the solar wind wanes. Free: Aurora Alerts.
THE NITROGEN FRINGE: Last night, as the solar wind buffeted Earth's magnetic field and energetic particles rained down on the upper atmosphere, Markus Varik witnessed a magnificent display of auroras over Tromsø, Norway. "Observers on the ground were awestruck," he says, "especially by the low-hanging band of vivid pink."
This is called "the nitrogen fringe." Most auroras are green--a verdant glow caused by energetic particles from space hitting oxygen atoms 100 km to 300 km above Earth's surface. Pink appears when the energetic particles descend lower than usual, striking nitrogen molecules at the 100 km level and below.
"It was one of the most prominent shows we've had this season," says Varik. Eva Kristiansen of Tromsø saw the fringe, too. "The colors were amazing!" she says.
INTERSTELLAR ASTEROID "LIKE NOTHING SEEN BEFORE": In Oct. 2017, the Pan-STARRS 1 telescope in Hawai'i picked up a faint point of light moving across the sky. At first it appeared to be an ordinary asteroid--but astronomers quickly realized it was something entirely different. The hurtling object, since named "'Oumuamua," came from interstellar space. At the time of its discovery, 'Oumuamua had just swung around the sun. Telescopes around the world swiveled to observe it before it could leave the Solar System. Findings from those rapid observations were published in the Nov. 20th issue of Nature, and they reveal a very strange object indeed:
Above: an artist's concept of interstellar asteroid 'Oumuamua [more]
According to a European Southern Observatory (ESO) press release, 'Oumuamua is "like nothing seen before." It is red, made of dense rock or metal, and is shaped roughly like a giant cigar at least 400 meters long.
These are the findings of a team of astronomers led by Karen Meech (Institute for Astronomy, Hawai`i, USA) who combined images from the ESO's Very Large Telescope in Chile with other large telescopes. 'Oumuamua varies dramatically in brightness by a factor of ten as it spins on its axis every 7.3 hours. "This unusually large variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape," says Meech.
The asteroid's dark red color is probably caused by cosmic rays irradiating its surface for millions of years in deep space. Cosmic rays have a similar coloring effect on asteroids and comets native to our outer Solar System.
Extrapolating 'Oumuamua's trajectory back in time, it seems to come from the direction of the star Vega. However, Vega itself moves and was not in the area when 'Oumuamua was last there ~300,000 years ago. 'Oumuamua may well have been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with the Solar System.
Researchers estimate that interstellar asteroids similar to 'Oumuamua pass through the inner Solar System about once per year, but they are faint and so have been missed until now.Only recently have survey telescopes such as Pan-STARRS become powerful enough to discover them.
"We are continuing to observe this unique object," says team member Olivier Hainaut from the ESO in Garching, Germany. "And now that we have found the first interstellar rock, we are getting ready for the next ones!" Stay tuned.
Realtime Space Weather Photo Gallery
A CRYSTAL BALL IN THE STRATOSPHERE: For the first time ever, a crystal ball has visited the stratosphere. The students of Earth to Sky Calculus launched it on Oct. 19, 2017--a combination optics experiment and fundraiser. Watch the video as the crystal orb travels onboard a giant helium balloon 93,000 feet above Earth's surface, stretching, focusing, and inverting the incredible landscape of the Sierra Nevada mountains behind it:
This 800 gram crystal ball contains an embedded model of the Solar System, including the sun, eight planets and their moons. It makes an incredible gift for anyone interested in space.
We have flown only a small number of these heavyweight crystal balls. You can have one for $199. Each crystal ball comes with a unique gift card showing the item at the edge of space and telling the story of its flight. It also comes with a complementary crystal stand so you can display this unique keepsake on a desktop or shelf. QUANTITIES ARE LIMITED.
Far Out Gifts: Earth to Sky Store
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