Sky's Up July-September 2017 - Page 34


18 above the clouds on Venus can see occasional transits of Mercury . NASA ’ s rovers on Mars have returned images , converted to video , of transits of Mars ’ satellites Phobos and Deimos . Both are too small to completely cover the Sun ’ s disk . NASA ’ s Mars orbiters have captured the shadow of Phobos crossing Mars ’ surface as weather satellites have captured the Moon ’ s shadow crossing Earth ’ s surface . The Martian moons ’ transits are frequent for a band centered on Mars ’ equator during “ eclipse seasons ” around the times of the vernal and autumnal equinoxes on the planet . These are the times when the Sun ’ s position in the sky intersects with their orbits , which are in the same plane as Mars ’ equator . Their short orbital periods , hours to a couple of days , allow many events to occur during the season . ( These parameters are not true for Earth ’ s Moon , whose orbital plane is tilted off of Earth ’ s equatorial plane and changing orientation all the time . In addition , the Moon ’ s orbital speed is much slower . The tilt leads to there only being two or three eclipse seasons per year , when the Sun and Moon are both close to the intersection of the projection Earth ’ s equator and the Moon ’ s orbit on the sky .) From Jupiter ’ s cloud tops ( there is no hard or liquid surface ), Jupiter ’ s four largest satellites , Io , Europa , Ganymede , and Callisto , all appear much larger than the Sun when they occult ( eclipse ) it . Jupiter ’ s 65 other satellites ( two new discoveries just announced , with , perhaps , more to be discovered ) are all small and fairly distant so an observer there would see them transit the Sun ’ s disk . The sidebar describes other phenomena that can be observed from Earth . They involve Jupiter and the four large Galilean satellites and phenomena involving each other . As seen from Earth , Saturn ’ s largest satellite , Titan casts a black , pinprick shadow on the disk of the planet during Saturn ’ s eclipse seasons . Observing from Saturn ’ s cloud tops ( there is no hard or liquid surface ), Titan appears much larger than the Sun when it occults ( eclipses ) the Sun . Saturn ’ s 61 other satellites ( with , perhaps ,
COURTESY OF NASA / JPL-Caltech / Malin Space Science Systems / Texas A & M Univ .
This set of three images shows views three seconds apart as the larger of Mars ’ two moons , Phobos , passed directly in front of the sun as seen by NASA ’ s Mars rover Curiosity . For a video of the event , click the image .
more to be discovered ) are all small and fairly distant so an observer there would see them transit the Sun ’ s disk . Saturn ’ s rings would blot out the Sun on the cloud tops during Saturn ’ s eclipse seasons but just what that would look like is somewhat uncertain . NASA ’ s Cassini mission has provided many spectacular images of conjunctions of Saturn ’ s satellites . Observing mutual eclipses , transits and occultations is not impossible from Earth , but difficult . The satellites of Uranus would only be seen to transit the Sun from its cloud tops . Mutual events during eclipse season would be very difficult to observe from Earth . Triton is the largest satellite of Neptune but it would still not create a total eclipse of the Sun . Neptune ’ s many other satellites only do transits during Neptune ’ s eclipse seasons . Mutual events would be extremely difficult to observe from Earth . Though it is considered a dwarf planet , Pluto ’ s five satellites would still have all the events mentioned for Jupiter but even its largest moon , Charon , only transits the distant Sun . The last eclipse season was in the 1980s and the mutual events of Pluto and Charon were used to map each other , at very low resolution , from Earth . The next eclipse season is around 2100 CE . We on Earth are fortunate to be able to see the unique beauty and the phenomena revealed by a total solar eclipse . Go out and watch one !
Sky ’ s Up
north carolina south carolina As it gears up for the final stretch through South Carolina, the path of the total solar eclipse creates a narrow corridor across the southwest corner of North Carolina and the northeast corner of Georgia. The scenery will be stunning as the shadow makes it way across Great Smoky Mountains National Park and the communities nestled in Nantahala National Forest. The park is planning three public viewing event, including one at Oconaluftee Visitor Center in Cherokee, N.C. Observers might want to purchase a detailed eclipse map from the Great Smoky COURTESY OF Michael Zeiler, Mountains Association. The only city on the centerline in this slice of North Carolina is Andrews. This small town of less than 3,000 will spend 2 minutes and 39 seconds in totality, beginning at 2:34 p.m. EDT. The main viewing locale in Andrews is Heritage Park. The event is free, but observers can pay to reserve a 20x20 spot. For more information on happenings in Andrews, click here. Franklin, which will have 2 minutes and 30 seconds of totality beginning at 2:35 p.m. EDT, is hosting a Solar Eclipse Block Party to mark the event. Although totality will only pass over a small portion of the state, estimates that between 16,000 and 63,900 people will travel here. Totality begins its farewell tour as the Moon’s umbra crosses into South Carolina at 2:36 p.m. EDT. Weather permitting, millions of residents and visiting eclipse chasers will observe along this final leg of the path of totality. Interstate 95, which runs along the Atlantic seaboard, leads directly into the path. For this reason, estimates that between 547,000 and 2,188,000 people will travel to South Carolina for the eclipse. Totality begins in Greenville at 2:38 p.m. EDT. and lasts for 2 minutes and 12 seconds. The Children’s Museum of the Upstate will have a viewing event with children’s activities, free solar viewing glasses, live streams from NASA and more (museum admission fees apply). For more Greenville options, click here. At 2:41 p.m. EDT, the umbra reaches Columbia and plunges the state capitol into darkness for 2 minutes and 30 seconds. Lake Murray Park (which does have minor entrance fees) will host a public viewing event on both sides of the Dreher Shoals Dam and free solar glasses will be provided. You could ͼ͔Ѽ٥܁ѡ)ٕЁЁMɥЁ չѥ́Aɬɥѡ յɕ́)QЁɔЁѡݕѠ͔ɕѕѥ٥ѥ́ѡ)ɔȁёȁѡ̰ͥѡѕɱ͕́ ɕ)9ѥAɬ!́ЀȁPѡ́ѡ͍)ȁѕ́Ё͕́ѽх丁́Ёɽ́Ѽѡаѡ)ѕɱ͕ٕ́ȁ15ɥMѕ)MхєAɬ15ձɥ ɱѽ)ѡͽѡɸѡѠѽх)ݡ͕ٕ́́ѡɔݥЁ(āє͕́́չȁѡܸ͡)QЁɔЁѡѡɄٕ)ѡ́хѽݸɔ)ѕȁѡɽ՝Ʌ́5ɥ9ѥ)ɕаѡѕȁѡ5é͡܁Ʌ)݅䁙ɽѡѱͭ́ɽ́ѡ)ѱѥ=Ȁԁѕ́ɔЁ́)ѡѣéə%́݅ѡյɄ)ݥٔ́ݕՍ͕ٕ)ɕэɽЁѼа䁽)ѡ͔ݥɕ䁉́Ѽэѡ)Ёѽхͽȁ͔ѡЁ͕́ЁѼɅѡ)ѥս́TLɥఀи)ɝ)%Ёݥхѽх䁽ͥѕ́Ѽ́݅䁽ٕȁѡ)ѡЁɹȁɝ́ѡյɄɽ͕́ѡɑȁЀ)PЁ͕́Ʌٕȁѡ х9ѥ)ɕи͔͕́ݥ݅ЁѼ͔唁ѡݕѡ)͔ѡɔ́ȁѡɽ՝ɔ͔䁙ȁեɕɽє) ٥ݡݥٔѱ́ѡȁѕ́ѽх䰁)ȁѡЁЁɝP Ʌѽݸ ȁɔѡ(ѥ͕́ѽх䰁ԁɅٕ́)Ё!݅؁Ѽ ѽݡݥȁѕ́)͕́ѽх͔ЀԁP ѽѡ)ѕɱչѥ́ɐMY䁅ɔIո) չ䰁ݡݥݥѠ͔ٕ́́͡)̸ͥQЁɔЁٕ́ѡչ䰁ɔ)ѡ͔ȁхєɬɥQձɝMхєAɬ)٥٥ݥٕЁѡЁՑ́Սѥѥ٥ѥ́ͥє)̸͔Qх䁉́Qձ́Ѐ؁P)́Ȁȁѕ̸͕́ȁɔɵѥɔ) =UIQMd=5iȰܹɕɥ͔)ɝѥ́ѡѕɱѡѠѽх)ɐMY) =UIQMd=5iȰܹɕɥ͔)ȁѡ́յхٕаЁ́хЁѼٔݕѠɵѥɑȁѼɔԁeЁ́)Ѽɥѽх䄁ȁɕ͕ɍ́٥хQݥͥѕ́ݕɔ͕́ɕɕѕɥ́ȁѡ)ɔ]ɕɥ䁽ȁѡЁȁɔͼԁٔѡЁ+ͽ+ѥ͔+ܹ͕ݥ͔+ܹɕхɥ͔+ܹ͔ܹɜ+͔ܹ̈́()MѠ ɽѥ́ѡѕɱ)ѡѠѽх) ѽ Ʌ ɽ́!!AѠ1)-ݕ15ɥ15ձɥ1)5Ʌ䃊1᥹ѽ5 ٥Aɥѽ)MѕMхєAɬMٕɕЃ)]ɔM̃]ѕɱ)х݄)ѡ՝ȁхѕ́ɔɕɔѡѠѽх䁅Յ䁍ɽ͕́ѡɽ՝ѥͱٕ́5х%݄)ݕQͽѡɹЁѥ5хݥ͕ٔ́ѽх䁥ɕݥѠ́ɽ̸%ѡѥ䁍ɹȁ)%݄ѡЁ́ѡѠѡѽх͔ݥЁ̸͕)M䃊d)U)M䃊d)U(