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Notes on meteor showers, space exploration events, and astronomy-related anniversaries from January through March 2017.
Sunrise Local Noon Sunset
January 1 7:25 am PST 12:13 pm PST 5:02 pm PDT
February 1 7:13 am PST 12:23 pm PST 5:34 pm PST
March 1 6:40 am PST 12:22 am PST 6:04 pm PST
(Times are for San Francisco, CA, and will vary slightly for other locations.)
The first known asteroid, 1 Ceres, was discovered on January 1, 1801 by Giuseppe Piazzi. At first referred to as "planets," these objects were given their own individual symbols, just as the planets had been, but by about the mid-1800s., astronomers began to realize that an ungainly number of them were being found. Although their motions against the background of stars resembled the motions of planets, to the telescopes of the time, these objects looked only like starlike points, prompting Sir William Herschel to propose the name "asteroid," meaning (oddly enough)"starlike." The number of known asteroids skyrocketed when astrophotography was used to search for them. As of March 2016, 750,000 asteroids were known well enough to be given ID numbers, and several have now been photographed up close by spacecraft such as NASA's Galileo, Dawn, and New Horizons, and Japan's Hayabusa. Discovered with a 3-inch refracting telescope, Ceres is not visible to the unaided eye. In modern binoculars or a medium-size telescope, it can be observed this season as a faint point of light slowly changing its location from the stars of Pisces the Fishes into Aries the Ram.
On January 24, 1986, NASA's Voyager 2 flew past the planet Uranus, becoming the only spacecraft to visit that planet. Barely within reach of the naked eye, Uranus was discovered on March 13, 1781 by William Herschel, who thought he was looking at a comet when he first saw it in his telescope. With that observation, Herschel doubled the size of what was then thought to be the known Universe. Uranus is currently located in the constellation Pisces the Fishes, and is usually difficult to find unless some bright object passes nearby. Fortunately, the Moon does exactly that on the nights of January 5 (appearing less than 4 degrees from it—easily in the same binocular field) and February 1 (a more distant 6 degrees away), while Mars makes a close conjunction on February 26, separated by only a half-degree (about the apparent width of a full Moon). Remember: since planets don't twinkle like stars do, look in a telescope or binoculars for a steadily-shining, pale-green dot.
February 2 is known as Candlemas, which is the 40th day of Christmas. It's also known in folklore as Groundhog Day, originating in Pennsylvania German communities in the 1800s. Supposedly, if a groundhog crawls out of his burrow on this day and sees his shadow, there will be six more weeks of winter weather. If he doesn't, there will be an early thaw. Supposedly. For all the hoopla, various ceremonial groundhogs from Punxsutawney Phil, Staten Island Chuck, and General Beauregard Lee to their Canadian counterparts such as Wiarton Willie, Manitoba Merv, and Fred la marmotte have a collective accuracy of only 37%, according to record-keepers. Which is not impressive. For astronomers, however, February 2 is a cross-quarter day, or the approximate halfway point between the winter solstice and the spring equinox—the daylight period is clearly getting longer as the noonday Sun climbs higher in the sky.
On February 11, Comet 45P/Honda-Mrkos-Padusakova is nearest to Earth and theoretically at its brightest, although astronomers are never positive just how bright a comet will get. At the time of this writing (January 2017), some forecasts suggest that 45P might be observable through 10x50 binoculars under ideal locations. Unfortunately, on that date, the Moon will be only a day past full, and its bright light may wash the comet from view. Still, depending on how the comet behaves as it approaches Earth, it might be worth watching for.
Galileo Galilei was born in Pisa on Feb 15, 1642. The oldest of six children, he picked up his musician father Vincenzo Galilei's skills at playing the lute, considered joining the clergy, chose to study medicine instead, and discovered his true calling in mathematics and natural philosophy, teaching art, geometry, and mechanics. Hearing of optician Jan Lippershey's invention of the "spyglass" in 1608, Galileo made his own 3-power instrument a year later and followed with a succession of improved devices as powerful as 30x. With these, he made some of the first astronomical observations with what would eventually become known as the telescope, earning for himself the historical title of "Father of Observational Astronomy."
On February 15, 2013, a fireball fell over Chelyabinsk in Russia. Scientists estimate that the original object was about 19 meters (20 yards) across, and fortunately, it exploded in the atmosphere and never hit the ground. Still, the explosion released about 30 times the energy of the atomic bomb dropped on Hiroshima during World War II. The shock wave from the explosion shattered windows and sent about 1500 people to the hospital for cuts from broken glass.
Pluto was discovered by Clyde Tombaugh from Lowell Observatory in Tucson, AZ on February 18, 1930 and officially named on March 24 that same year, being given a name from Roman mythology suggested by 11-year old Venetia Burney (pictured). For the next 76 years, it was considered the ninth planet in the solar system, until in 2006, the International Astronomical Union reclassified it and several other small bodies (including asteroid 1 Ceres) as "dwarf planets."
The annular solar eclipse of February 26 is centered over the southern Atlantic Ocean. Starting in the southeastern Pacific, the path of the Moon's shadow, from which the annulus can be seen, crosses land only along a narrow strip that slices across southern Chile and Argentina, then crosses the Atlantic, making landfall again in Angola, with the very end just reaching the Congo and a tiny bit of Zambia before leaving Earth's surface. During an annular eclipse, the Moon is a little farther away than during a total eclipse, so it appears slightly smaller in the sky and so doesn't quite cover the Sun's disk. Like a dime laying on top of a penny, it leaves a thin ring of the Sun's disk visible around it. Although thin, this ring (or annulus) is bright enough to wash the Sun's faint outer atmosphere, or corona, from view. Areas within about 2000 miles north or south of the annular path will be able to observe a partial solar eclipse, which means that observers in large parts of South America, Africa, and Antarctica may see it, but no part of the eclipse will be visible from the United States.
The March (or Spring) Equinox occurs on March 20 at 2:29 a.m. PDT (for the southern hemisphere, where seasons are reversed, this is the Autumnal Equinox). There are several ways to think about what's happening here. One is that on its annual trip along the ring of the Zodiacal constellations, the Sun is at one of two points where it crosses the celestial equator (the plane of Earth's equator), in this case, passing from the south celestial sphere to the north. As seen from the ground— it rises due east and sets due west. At this point in its orbit, Earth's axis of rotation is perpendicular to the Earth-Sun line and is tilted neither toward nor away from the Sun. As a result, the terminator—the boundary between the planet's daytime and nighttime halves—runs straight through the north and south poles. Theoretically, day and night are of equal length. However, the theory works only if the Sun is a point-source rather than a disk half a degree in diameter, which introduces a discrepancy of two minutes right there. Also, Earth's atmosphere has an optical effect, refracting sunlight and creating a mirage on the horizon that appears a few minutes before the Sun's actual rising time and which lingers a few minutes after its setting time. According to the U.S. Naval Observatory, the actual date that day and night are equal in length varies with latitude—for 40 degrees north, it's about March 17.
Asteroids discovered in January-March, with identifying clues in parentheses:
16155 Buddy (Holly, rock 'n' roller), 4147 (Beatle John) Lennon, 17627 (nursery rhyme character) Humptydumpty, 9387 ("Through the Looking Glass" character) Tweedledee, 17681 ("Through the Looking Glass" character) Tweedledum, 91007 ("James Bond" creator) Ianfleming, 249516 Aretha (Franklin, singer), 25930 (movie producer Steven) Spielberg, 15092 (singing group) Beegees, 9617 (Monty Pythoner) Grahamchapman, 9618(Monty Pythoner) Johncleese, 9619(Monty Pythoner) Terrygilliam, 9620(Monty Pythoner) Ericidle, 9621 (Monty Pythoner) Michaelpalin, 9622 (Monty Pythoner) Terryjones, 91287 (singing duo) Simon-Garfunkel, 26858 (children's TV icon) Misterrogers, 2709 (astronomer Carl) Sagan, 4659 ("Star Trek" creator Gene) Roddenberry, 22521 (rock group) ZZTop, 9766 (author Ray) Bradbury, 18610 ("Hitchhiker's Guide to the Galaxy" character) Arthurdent
Created by Morrison Planetarium staff, these go-to resources cover events occurring between January and March 2017.
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