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2012 Venus and Jupiter will appear unusually close in the sky over the next month. The planetary conjunction will be easily visible to the unaided eye because Venus will appear brighter than any background star, and Jupiter will be nearly as bright. To see the near-alignment, simply look to the west after sunset. At their closest, on March 15, the two planets will appear only about three degrees apart. The planets will not be significantly closer in space - Venus will just be passing nearly in front of Jupiter as seen from the Earth. In the above image composite taken late last week from Catalonia, Spain, a bright crescent moon appears to the right of Venus, while Jupiter appears near the top of the image. The distant sun-illuminated spheres were photographed behind a sculpture depicting the legendary battle between a warrior and a dragon. A gallery of conjunction images is visible on the Asterisk -- APOD's discussion board. Please feel free to contribute. The next Jupiter-Venus conjunction will occur in May 2013.
2008 Welcome to the extra day in the Gregorian Calendar's leap year 2008! To celebrate, consider this grid of lunar eclipse pictures - starting in leap year 1996 and ending with February's eclipse - with the date in numerical year/month/day format beneath each image. Mostly based on visibility from a site in Turkey, the 3x4 matrix includes 11 of the 13 total lunar eclipses during that period, and fills out the grid with the partial lunar eclipse of September 2006. Still, as the pictures are at the same scale, they illustrate a noticeable variation in the apparent size of the eclipsed Moon caused by the real change in Earth-Moon distance around the Moon's elliptical orbit. The total phases are also seen to differ in color and darkness. Those effects are due to changes in cloud cover and dust content in the atmosphere reddening and refracting sunlight into Earth's shadow. Of course, the next chance to add a total lunar eclipse to this grid will come at the very end of the decade.
2004 Today, February 29th, is a leap day - a relatively rare occurrence. In 46 BC, Julius Caesar, pictured above in a self-decreed minted coin, created a calendar system that added one leap day every four years. Acting on advice by Alexandrian astronomer Sosigenes, Caesar did this to make up for the fact that the Earth's year is slightly more than 365 days. In modern terms, the time it takes for the Earth to circle the Sun is slightly more than the time it takes for the Earth to rotate 365 times (with respect to the Sun -- actually we now know this takes about 365.24219 rotations). So, if calendar years contained 365 days they would drift from the actual year by about 1 day every 4 years. Eventually July (named posthumously for Julius Caesar himself) would occur during the northern hemisphere winter! By adopting a leap year with an extra day every four years, the calendar year would drift much less. This Julian Calendar system was used until the year 1582 when Pope Gregory XIIIprovided further fine-tuning when he added that leap days should not occur in years ending in "OO", unless divisible by 400. This Gregorian Calendar system is the one in common use today.
2000 Even as leap days go, today is a remarkable one. In 46 BC, Julius Caesar, pictured above in a self-decreed minted coin, created a calendar system that added one leap day every four years. Acting on advice by Alexandrian astronomer Sosigenes, Caesar did this to make up for the fact that the Earth's year is slightly more than 365 days. In modern terms, the time it takes for the Earth to circle the Sun is slightly more than the time it takes for the Earth to rotate 365 times (with respect to the Sun -- actually we now know this takes about 365.24219 rotations). So, if calendar years contained 365 days they would drift from the actual year by about 1 day every 4 years. Eventually July (named posthumously for Julius Caesar himself) would occur during the northern hemisphere winter! By adopting a leap year with an extra day every four years, the calendar year would drift much less. This Julian Calendar system was used until the year 1582 when Pope Gregory XIII added that leap days should not occur in years ending in "00" except if divisible by 400, providing further fine-tuning. This Gregorian Calendar system is the one in common use today. Therefore, even though this year 2000 ends in "00", it remains a leap year, and today is the added leap day. That makes today the first leap day for a centurial year since year 1600 and the second such leap day of the Gregorian Calendar.
1996 Today, February 29th, is a leap day - a relatively rare occurrence. Advised by Alexandrian astronomer Sosigenes, Roman dictator Julius Caesar, pictured above in a self-decreed minted coin, created a calender system in 46 BC that contained one leap day every four years. The reason for adding leap days was that a year - defined by the time it takes the Earth to circle the Sun - does not actually take an exact integer number of days - defined by the time it takes for the Earth to rotate once. In fact, one year by these astronomical definitions is about 365.24219 days. If all calendar years contained 365 days, they would drift from the actual year by about 1 day every 4 years. Eventually July (named posthumously for Julius Caesar himself) would occur during the northern hemisphere winter! By making most years 365 days but every fourth year 366 days, the calendar year and the actual year remained more nearly in step. This "Julian" calender system was used until the year 1582 when Pope Gregory XIII added that leap days should not occur in years ending in "00" except if divisible by 400, providing a further fine tuning. This "Gregorian" calender system is the one in most common use today.
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