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(Times are for San Francisco, CA, and will vary slightly for other locations.)
The Space Age began on October 4, 1957, when the Soviet Union launched the unmanned Sputnik 1 satellite into orbit. Today, there are approximately 1000 operational satellites circling the planet, some in low orbit around 200 miles up and others at the geosynchronous orbit 23,500 miles above the surface, where they orbit at the same rate at which Earth rotates, and so maintain a position above the same spot on the surface. During the early hours on any dark night, away from bright lights, about half-a-dozen satellites can be seen with the naked eye, looking like faint stars slowly following straight-line paths across the heavens.
On October 6, 1995, 51 Pegasi b, the first-known extrasolar planet orbiting a sunlike star was discovered. Though the planet itself—a gas giant 50 light years away in the constellation Pegasus the Flying Horse—is not visible to telescopes, the star it orbits, 51 Pegasi, is visible in the evening sky (the planet is designated with the letter "b"). Just within the grasp of the unaided eye, it is located just beyond the western side of the Great Square of Pegasus, about halfway between the stars Alpha and Beta Pegasi (aka Markab and Scheat, respectively). Because of the constellation in which it’s found, some have suggested the name "Bellerophon," after the hero from Greek myth who is traditionally associated with Pegasus.
On October 7, the distant, green giant Uranus is at opposition, or opposite the Sun in the sky, rising at sunset and setting at sunrise. This makes it visible all night as it slowly crosses overhead against the stars of Pisces the Fishes, which you can imagine as a "V" bordering the eastern and southern sides of the Great Square of Pegasus. Uranus is about 3 degrees south of the halfway point along the southern arm of the "V." Uranus was the first planet discovered telescopically, with a distance about twice that of Saturn’s from the Sun. Visible as a tiny, greenish disk, Uranus is tipped over on its axis, rolling along in its orbit around the Sun instead of spinning like a top like the other planets. At four times Earth’s diameter and possessing at least 27 moons, Uranus has been visited by only one spacecraft—Voyager 2, which made a quick flyby in 1989. When Sir William Herschel discovered Uranus in 1781, he could see that it wasn’t a starlike point, but he thought at first that it was a comet. He proposed naming the new planet in honor of King George III, who was dealing with a small uprising in the American colonies at the time, but the astronomical community voted for a more traditional name drawn from mythology.
The total lunar eclipse on October 8 is for early-risers, taking place from 2:14–5:35 a.m., PDT, with totality from 3:24–4:24 a.m. As the full moon passes through Earth’s shadow, the Sun’s light is bent by our planet’s atmosphere and filled in with the reddish light that isn’t scattered in the air to produce our blue skies. During the partial phase—that is between 2:14 and 3:24, look for the curvature of Earth’s shadow, which shows that our planet is spherical. For more on this event, visit eclipse.gsfc.nasa.gov.
A close encounter with Mars: Comet C/2013 A1 Siding Spring passes 83,000 miles from Mars on October 19. That distance is equivalent to about 10 Earth-diameters or 20 Mars-diameters. At Mars’ distance from the Sun, the comet is probably not bright enough to be seen easily from Earth…but imagine the view from the surface of the red planet! NASA and the European Space Agency are taking precautions to shield their spacecraft from any possible debris shed by the comet and are altering their orbits so that they’ll be on the side of Mars away from the comet when the debris density is expected to be at its greatest. Meanwhile, the Curiosity and Opportunity rovers on the surface are thought to be well-protected by Mars’ atmosphere, which will cause any debris from the comet to burn up before it reaches the ground. After the most hazardous period has passed, the seven robotic spacecraft will turn their cameras and other instruments on the comet to see what they can observe.
Two weeks after the October 8 total lunar eclipse, a partial solar eclipse occurs on Thursday, October 23. In this case, the Moon is between Earth and the Sun, casting its shadow earthward. However, the dark, central portion of the shadow misses the planet, so from the ground, the Moon never completely covers the Sun’s disk. For San Francisco observers, first contact (when the partial eclipse begins) is at 1:52 p.m. PDT, with the Sun 38° high in the south-southwest and descending. Mid-eclipse occurs at 3:15 p.m. PDT, when the Sun is 30° high in the southwest. At that time, the Moon will encroach 50.4% across the Sun’s diameter, obscuring 39% of its disk. After that, the Moon continues sliding eastward, now moving away from the Sun’s face, with last contact ending the partial eclipse at 4:32 p.m. PDT, when the Sun’s altitude has dropped to 19° high in the southwest. Local times and the percent of obscuration will vary for other observing locations, with more coverage seen from farther north and less as seen from more southerly locations. The eclipse will occur later in the afternoon for locations farther east, with the eclipse still in progress at sunset for locations in the eastern half of the U.S.—only observers in the western states will be able to see the eclipse from beginning to end. Details can be found at eclipse.gsfc.nasa.gov.
The solar eclipse in October is only partial from wherever it is seen, but consider it practice for the future: American skywatchers will have an opportunity to see a total solar eclipse in 2017 as the path of the Moon’s shadow runs from Oregon through parts of Idaho, Wyoming, Nebraska, Kansas, Missouri, Kentucky, Tennessee, Georgia, and South Carolina. Eclipse-chasers will have to plan their trips carefully to place themselves on the narrow path of totality, and hopefully will have better luck than the first U.S. expedition to study a total eclipse that occurred on October 27, 1780. As this was during the American Revolutionary War, a group seeking to observe the eclipse requested permission from British forces to set up their observing station in enemy-held Penobscot Bay, Maine, which was granted in the name of science. However, as they watched, the party discovered that they had miscalculated the path and wound up just outside the zone of totality. More here on the 2017 eclipse as the date approaches, or visit eclipse.gsfc.nasa.gov.
Asteroids discovered in October: 2620 (Carlos) Santana in 1980, 214476 (comedian/satirist) Stephencolbert in 2005, 3623 (vaudevillian/actor Charlie) Chaplin in 1981, 21811 ("Tarzan" & "John Carter" creator Edgar Rice) Burroughs in 1999, 9007 (fictional superspy) James Bond in 1983, 2866 (vaudevillean Oliver) Hardy in 1961, 125071 ("Dracula" actor Bela) Lugosi in 2001, 115561 ("Dune" author) Frankherbert in 2003, 7672 (astrophysicist Stephen) Hawking in 1995, and 10221 (film director Stanley) Kubrick in 1997.
On October 30, 1938 Orson Welles celebrated Halloween by broadcasting his "War of the Worlds" radio play, dramatizing H.G. Wells’ (no relation) novel of a Martian invasion. Though we know that real "Martians" may be a long-shot, the presence of Mars itself in our sky is unquestioned: look low in the southeast just after sunset through the remainder of the year.
Construction of the International Space Station began on November 6, 1998, when the Zarya and Unity modules were docked together, providing the power-core for the orbiting structure. Now the size of a football field, the Space Station is the largest object ever built in space, and with a relatively-low orbital altitude of 230 miles, one of the brightest objects in the sky, occasionally surpassing the brightness of even the planet Venus. Find out when you can see it passing over your city at spotthestation.nasa.gov.
As of this writing, the European Space Agency has decided to attempt a landing on Comet 67P/Churyumov-Gerasimenko (or just "Comet 67P" for short) on November 11. Having accomplished a rendezvous with the comet, the Rosetta spacecraft settled into orbit in September and will deploy the smaller Philae lander, which it has been carrying since launch in 2004. Being only 2½ miles long, the small comet nucleus has very weak gravity, so Philae’s landing has been characterized more as a slow "docking," and to prevent the spacecraft from bouncing off the surface and escaping back into space, it will embed a pair of harpoons into the ice to anchor itself. Since the comet’s shape has been compared to that of a rubber duckie, the primary landing site would be at the top of the duckie’s head. For an early animation of the comet, showing its shape, see www.bbc.com. For a more recent, high-resolution view of its surface, see blogs.esa.int.
The Rosetta spacecraft is named after the Rosetta Stone, which contained a decree written in three different languages, helping to decipher Egyptian hieroglyphs. The Philae lander is named after an island where an obelisk was found containing the same decree, helping to fill in missing portions of the engravings on the Rosetta Stone. Scientists hope that the Rosetta mission will help decipher some of the secrets of the solar system when Philae makes contact with the surface of 67P.
Asteroids discovered in November, followed by their respective discovery years, include 7032 (Alfred) Hitchcock (1994), 12426 Racquetball (1995), and 11548 (comedian) Jerrylewis (1992).
On December 3, 1973, NASA’s Pioneer 10 spacecraft became the first to encounter the giant planet Jupiter. Now far beyond the planets, Pioneer 10 is headed in the general direction of the star Aldebaran in Taurus the Bull, 65 light years away, which it would reach in a bit over 2 million years if it were actually aimed for the star. Contact was lost with the spacecraft in 2003, after reception of the final, very weak signal. Pioneer 10 carries a "postcard" from Earth—a greeting to any possible extraterrestrials—showing a human male and female, the spacecraft, and a map of its journey from Earth relative to several known pulsars. The greeting was conceived and designed in part by astronomer Carl Sagan, who would’ve celebrated his 80th birthday this year on November 9.
Asteroids discovered in December include 849251 (former Assistant Supervisor of Morrison Planetarium and avid amateur astronomer) Kenwilson (2003), 19367 (rock group) Pink Floyd (1997).