When Edward Emerson Barnard peered through the 36-inch refractor at Lick Observatory on Sept. 9, 1892, and spotted Amalthea, it marked the first discovery of a moon of Jupiter in 280 years. Galileo had discovered the four largest jovian moons – Io, Europa, Ganymede, and Callisto – in 1610. Though this fifth moon was closerContinue reading "Sept. 9, 1892: Edward Emerson Barnard sees Amalthea"

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Looking for a sky event this week? Check out our full Sky This Week column.  September 8: The Moon joins Jupiter The waning Moon has moved from Cancer to Leo and is nearing the bright star Regulus, which marks the Lion’s heart. Our satellite will pass 0.6° south of Regulus at 4 P.M. EDT this afternoon.  AnContinue reading "The Sky Today on Wednesday, September 9: Visualize the ecliptic"

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Rocket launches this week On Thursday, Sept. 10 at 5:00 a.m. EST, a Long March 2D rocket is set to lift off from Jiuquan Satellite Launch Center in northern China’s Gobi Desert carrying an undisclosed payload, according to tracking from Next Spaceflight. The rocket is operated by the state-owned space contractor China Aerospace Science andContinue reading "SpaceX closes out SES’s O3b mPower constellation"

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On Sept. 8, 2016, the Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer (OSIRIS-REx) mission launched from Cape Canaveral, setting off on its 4.4-billion-mile (2 billion kilometers) journey to asteroid Bennu. About the size of an SUV, the OSIRIS-REx spacecraft carries several cameras, an altimeter used to create maps of Bennu, and anContinue reading "Sept. 8, 2016: OSIRIS-REx launches"

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Looking for a sky event this week? Check out our full Sky This Week column.  September 7: Venus and Spica, side by side The Moon has now skimmed through the morning sky over to Cancer, where it checks in on Jupiter — and you can check in on them both before dawn.  The Moon rises around 3:30Continue reading "The Sky Today on Tuesday, September 8: The Moon joins Jupiter"

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James Van Allen, who was born in Iowa on Sept. 7, 1914, showed talent and interest in science and math from an early age. A major in physics from Wesleyan College in 1935 was followed by a Ph.D. in nuclear physics in 1939. Before and after World War II – during which he developed antiaircraftContinue reading "Sept. 7, 1914: The birth of James Van Allen"

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Wouldn’t a free-floating planet eventually cross paths with a star or even a black hole and start revolving around it? YinToronto, Ontario Free-floating planets (FFPs) or rogue planets are bodies that move through space by themselves, not locked into an orbit around a star. While some may have begun as typical planets flung out ofContinue reading "Why aren’t free-floating planets captured when they fly past stars?"

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Looking for a sky event this week? Check out our full Sky This Week column.  September 6: The Moon and Mars in Gemini Venus has pulled away from the bright star Spica in Virgo, which it met in the sky last week, and tonight stands side by side with the star as they set together following sunset.Continue reading "The Sky Today on Monday, September 7: Venus and Spica, side by side"

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The fall of 1618 was a standout when it came to notable comets, boasting three visible to the naked eye. In late August, C/1618 Q1 appeared, first spotted in the skies over Hungary. Johannes Kepler observed the comet throughout the month of September, spotting it from Linz, Austria, through a small telescope on Sept. 6.Continue reading "Sept. 6, 1618: The first comet seen through a telescope"

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