After spending the 1850s at Harvard Observatory calculating orbits, Asaph Hall became an assistant at the U.S. Naval Observatory at Washington, D.C., in 1862. He was quickly promoted, and by 1873 had not only held several scientific discussions with Abraham Lincoln during the president’s visits to the observatory, but had also been put in chargeContinue reading "Aug. 11, 1877: Asaph Hall discovers Deimos"

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Looking for a sky event this week? Check out our full Sky This Week column.  August 10: Open cluster NGC 7243 In the evening sky, Venus is reaching dichotomy, the moment when it is exactly half-lit. You’ll find magnitude –4.4 Venus some 20° high in the west as the Sun sets. It’s so bright, it will beContinue reading "The Sky Today on Tuesday, August 11: Venus, half-lit "

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Rocket launches this week On Monday, Aug. 10, a Long March 7A rocket carrying an undisclosed payload broke apart roughly one minute and 27 seconds after lifting off from Wenchang Space Launch Site at 8:02 a.m. EST. Footage from online livestreams captured the failure in real time; Chinese state media had not released any informationContinue reading "A Long March 7A failure opens a week of Starlink launches"

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Some 1.3 billion years ago, when multicellular organisms were just emerging on Earth and life was still confined to the ocean, two behemoth black holes smashed together in a far-flung galaxy. The collision was so powerful that it jolted the universe, creating a ripple in the fabric of space-time that traveled across the cosmos atContinue reading "How gravitational waves transformed our universe"

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Which naked-eye star is richest in metals and what is the estimated mass of the metal contained therein? ThomasMineral, Virginia In astronomer-speak, metals refer to elements heavier than helium. The first stars that lit up the universe were very metal-poor, since hydrogen and helium were just about the only materials around after the Big Bang. TheseContinue reading "Which naked-eye star is richest in metals?"

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On Aug. 10, 1990, the Magellan orbiter arrived at Venus and was inserted into orbit. Its goal was to map the surface of the planet, using radar to peer beneath the cloudy atmosphere. Launched aboard the Space Shuttle Atlantis in May 1989, Magellan was the first deep space probe launched from a shuttle. Budget constraintsContinue reading "Aug. 10, 1990: Magellan enters venusian orbit"

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Looking for a sky event this week? Check out our full Sky This Week column.  August 9: The Moon and Mars This evening, the small constellation Lacerta sits just below cross-shaped Cygnus in the eastern sky after dark. The zig-zagging outline of the Lizard lies roughly 20° east (to the lower left early in the evening) ofContinue reading "The Sky Today on Monday, August 10: Open cluster NGC 7243 "

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Anushtup Roy Choudhury from Kolkata, India Looming over the Himalayas in this vista are the Rho Ophiuchi cloud complex and the Blue Horsehead Nebula (IC 4592). The former’s blue reflection nebulae, red clouds of emission, and dark dust lanes spread across Ophiuchus and Scorpius some 460 light-years away. The latter, lit by the blue subgiantContinue reading "A colorful cosmic canvas"

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The Soviet Luna program, designed for lunar research and mission planning, ran from 1959 to 1976. On Aug. 9, 1976, Luna 24, the final mission of the program, launched from the Baikonur Cosmodrome in present-day Kazakhstan. The probe landed on the Moon’s surface nine days later, in the Mare Crisium (Sea of Crises), a previouslyContinue reading "Aug. 9, 1976: Luna 24 blasts off"

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Looking for a sky event this week? Check out our full Sky This Week column.  August 8: Sagittarius’ Little Gem The Moon passes 4° north of Mars at 2 A.M. EDT; the pair is visible together in the early-morning sky, some 30° high in the east an hour before sunrise. They straddle the border of Gemini andContinue reading "The Sky Today on Sunday, August 9: The Moon and Mars"

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A pioneer mission in astrometry – the measurement of the position, distance, motion, brightness, and color of stars – the European Space Agency’s (ESA) High Precision Parallax Collecting Satellite, or Hipparcos, launched on Aug. 8, 1989. There were immediately problems when a rocket-engine failure kept Hipparcos from reaching its planned orbit. However, the satellite wasContinue reading "Aug. 8, 1989: The Hipparcos satellite launches"

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Looking for a sky event this week? Check out our full Sky This Week column.  August 7: A lunar occultation of the Pleiades Let’s spend tonight with the Little Gem, a planetary nebula also cataloged as NGC 6818. It is highest in the sky around 11 P.M., when it is some 35° above the southern horizon. It’sContinue reading "The Sky Today on Saturday, August 8: Sagittarius’ Little Gem"

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On August 12, the New Moon’s shadow will fall over a portion of Earth’s surface. When that happens, the Sun will temporarily disappear from the sky in a total solar eclipse. These breathtaking events are spectacular and ethereal, as the sky falls dark during the day, leaving only the soft glow of our star’s outerContinue reading "How to see the August 12 total solar eclipse"

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Meterorite ALH 84001 fell to Earth from Mars about 13,000 years ago, landing in the Allan Hills region of Antarctica. It was discovered in 1984 and taken to the Johnson Space Center, where in 1994 researchers saw possible signs of life: carbonate minerals and microscopic structures that resembled nanobacteria. Further research commenced, and on Aug.Continue reading "Aug. 7, 1996: NASA announces martian life"

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Looking for a sky event this week? Check out our full Sky This Week column.  August 6: Mercury moves south of Pollux The Moon passes 5° north of Uranus in Taurus at 1 P.M. EDT. The pair is visible earlier in the morning, with the Moon rising shortly before midnight on the 6th along with the PleiadesContinue reading "The Sky Today on Friday, August 7: A lunar occultation of the Pleiades"

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Friday, August 7The Moon passes 5° north of Uranus at 1 P.M. EDT. The pair is visible in the early-morning sky, along with a lunar occultation of the Pleiades just after moonrise. Check out the August 7 entry in last week’s Sky This Week column for more details.  Late tonight, there’s a good hour ofContinue reading "The Sky This Week from August 7 to 14: A solar eclipse and shooting stars"

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NASA launched its Mars rover Curiosity inside the Mars Science Laboratory (MSL) on Nov. 26, 2011. Complete with 10 science instruments and 17 cameras, the robot can analyze mineral types, search for signs of microbial life, and take color panoramas of the Red Planet’s surface. Curiosity’s landing on Mars was a new process, nicknamed theContinue reading "Aug. 6, 2012: Curiosity lands on Mars"

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Visible in Scotland, the total solar eclipse of Aug. 2, 1133, featured nearly 4½ minutes of totality. This eclipse provides just one of many historical examples of people wrongly associating a celestial spectacle with an earthly event: In his Historia Novella, written between 1140 and 1143, English historian William of Malmesbury linked the eclipse withContinue reading "Aug. 2, 1133: A total eclipse is misremembered"

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Looking for a sky event this week? Check out our full Sky This Week column.  August 1: Open cluster NGC 6709 Mercury reaches its greatest western elongation at 4 A.M. EDT, standing 19° from the Sun. The tiny planet reaches an altitude of almost 5° above the eastern horizon an hour before sunrise, glowing at magnitude 0.2.Continue reading "The Sky Today on Sunday, August 2: Mercury at greatest western elongation"

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Born Aug. 1, 1818, Maria Mitchell was raised in the Quaker tradition, which allowed equal education for boys and girls. This, plus lessons from her father, afforded her the opportunity to become skilled in astronomy, mathematics, and navigation. After a brief stint as a teacher, she became the first librarian of the Nantucket Antheneum. SheContinue reading "Aug 1, 1818: The birth of Maria Mitchell"

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