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Saturday, February 29, 2020
Tom Steyer To Drop Out Of 2020 Presidential Race
Biden Wins South Carolina Primary, AP Projects
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APOD - Julius Caesar and Leap Days
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2020 February 29
Image Credit & License: Classical Numismatic Group, Inc., Wikimedia
Explanation: In 46 BC Julius Caesar reformed the calendar system. Based on advice by astronomer Sosigenes of Alexandria, the Julian calendar included one leap day every four years to account for the fact that an Earth year is slightly more than 365 days long. In modern terms, the time it takes for the planet to orbit the Sun once is 365.24219 mean solar days. So if calendar years contained exactly 365 days they would drift from the Earth's year by about 1 day every 4 years and eventually July (named for Julius Caesar himself) would occur during the northern hemisphere winter. By adopting a leap year with an extra day every four years, the Julian calendar year would drift much less. In 1582 Pope Gregory XIII provided the further fine-tuning that leap days should not occur in years ending in 00, unless divisible by 400. This Gregorian Calendar system is the one in wide use today. Of course, tidal friction in the Earth-Moon system slows Earth's rotation and gradually lengthens the day by about 1.4 milliseconds per century. That means that leap days like today will not be necessary ... about 4 million years from now.
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
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The Finest Piano Concerto Of The Young Century (And The Rest Of The Best Of February)
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Friday, February 28, 2020
APOD - South Celestial Rocket Launch
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2020 February 28
Image Credit & Copyright: Brendan Gully
Explanation: At sunset on December 6 a Rocket Lab Electron rocket was launched from a rotating planet. With multiple small satellites on board it departed on a mission to low Earth orbit dubbed Running Out of Fingers from Mahia Peninsula on New Zealand's north island. The fiery trace of the Electron's graceful launch arc is toward the south in this southern sea and skyscape. Drifting vapor trails and rocket exhaust plumes catch the sunlight even as the sky grows dark though, the setting Sun still shinning at altitude along the rocket's trajectory. Fixed to a tripod, the camera's perspective nearly aligns the peak of the rocket arc with the South Celestial Pole, but no bright star marks that location in the southern hemisphere's evening sky. Still, it's easy to find at the center of the star trail arcs in the timelapse composite.
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.
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Thursday, February 27, 2020
Stocks In Free-fall: Dow Plunges Nearly 1,200 Points Among Widening Coronavirus Fears
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APOD - Two Hemisphere Night Sky
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2020 February 27
Image Credit & Copyright: Petr Horálek/ESO, Juan Carlos Casado/IAC (TWAN)
Explanation: The Sun is hidden by a horizon that runs across the middle in this two hemisphere view of Earth's night sky. The digitally stitched mosaics were recorded from corresponding latitudes, one 29 degrees north and one 29 degrees south of the planet's equator. On top is the northern view from the IAC observatory at La Palma taken in February 2020. Below is a well-matched southern scene from the ESO La Silla Observatory recorded in April 2016. In this projection, the Milky Way runs almost vertically above and below the horizon. Its dark clouds and and bright nebulae are prominent near the galactic center in the lower half of the frame. In the upper half, brilliant Venus is immersed in zodiacal light. Sunlight faintly scattered by interplanetary dust, the zodiacal light traces the Solar System's ecliptic plane in a complete circle through the starry sky. Large telescope domes bulge along the inverted horizon from La Silla while at La Palma, multi-mirror Magic telescopes stand above center. Explore this two hemisphere night sky and you can also find the Andromeda Galaxy and the Large and Small Magellanic Clouds.
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.
This is an automated email. If you notice any problems, just send me a note at gtracy@gmail.com. You can add and remove email addresses to this distribution list here, https://apodemail.org.Unsubscribe
Run better. Turn up your immunity. Say yes to MSG?
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