October's new moon will bring us a spectacular 'ring of fire' eclipse
The new moon occurs on Wednesday, Oct. 2, at 2:49 p.m. Eastern Daylight Time (1849 GMT), according to the U.S. Naval Observatory, and for observers in the southeastern Pacific islands and southern Chile and Argentina there will be an annular solar eclipse.
A new moon phase happens when the sun and moon are on the same line drawn from one celestial pole to the other. Usually, the moon appears to be above or below the sun as seen from Earth — it "misses" — but about twice a year the two are lined up just right so that we see a solar eclipse, the only time a new moon is visible at all. There are two types of solar eclipse: total and annular. In a total eclipse the sun appears to darken and turn black, though one can still see the solar corona, the sun's atmosphere. In an annular eclipse one can still see a ring (or annulus) of light around the moon without seeing the corona, which is overwhelmed by the small visible portion of the sun's disk. The eclipse on Oct. 2 is the latter kind. The reason for the different types of eclipses is that the moon's orbit is not a perfect circle; at times the moon is a bit closer or farther away. Though the difference is small, it is just enough to alter the apparent size of the moon in the sky.
An important note about observing solar eclipses: always use proper safety equipment, and never view the sun directly through optical aids of any kind. Even when the sun looks dimmed (as during sunsets or sunrises) a camera lens, low-power binoculars or spotter scope, let alone a telescope, will concentrate the light and the energy from the sun into your eye. This can cause retinal burns and permanent damage to one's eyesight, even blindness. The safest thing to do is view an eclipse through filtered glasses specifically designed for the purpose, or to project an image of the eclipse onto a large flat surface set up behind a telescope or mounted binoculars. As a general rule, if it isn't designed specifically for solar viewing, don't use it to look at an eclipse.
Related: How to observe the sun safely (and what to look for)
The eclipse path starts in the central Pacific Ocean on the morning of Oct. 3 (because it is on the other side of the International Date Line –12 hours ahead of UTC), near Palmyra Atoll (which has no permanent population). The nearest populated areas that will see at least a partial eclipse are Hawai'i and American Samoa. In Hawaii, the greatest partial eclipse will be visible from southern side of the island of Hawai'i the Big Island). In the town of Na'alehu, the eclipse starts before sunrise on October 3, which is at 6:13 am. Hawai'i Standard Time. Maximum eclipse is at 6:46 a.m., and the eclipse ends at 7:57 a.m. The moon will cover about 53 percent of the sun. As the sun gets above the horizon the moon will be towards the top; the "horns" of the partially eclipsed sun will point upwards.
In American Samoa, from Āpia, observers will see the eclipse already underway as the sun rises at 6:08 a.m. local time. Maximum eclipse, when about 29 percent of the sun is covered by the moon, is at 6:18 a.m., and the eclipse ends an hour later at 7:18 a.m. As American Samoa is in the Southern Hemisphere the horns will be pointed downwards, towards the horizon.
The full annular eclipse will be visible from Easter Island, where it begins at 12:23 p.m. local time on October 2 (as the moon's shadow has crossed the Date Line). The sun will be in the northeast. At 2:04 p.m. the sun will form the annular ring around the moon. Maximum eclipse is at 2:07 p.m. and annularity ends at 2:10 p.m., with the eclipse ending at 3:52 p.m.
Related: Why I'm going to Easter Island for the annular solar eclipse
After that the eclipse reaches mainland Chile and Argentina; in Argentina the annular eclipse is visible in Bahia Laura, in Santa Cruz Province, where it begins at 4:05 p.m. local time. Annularity starts at 5:25 p.m. and ends at 5:31 p.m. The eclipse ends at 6:43 p.m. with the sun low in the west.
The nighttime planets
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For those unable to see the solar eclipse, there are still the nighttime planets. At the latitude of New York City, Chicago, or Sacramento, Venus will be quite close to the horizon at sunset; with a clear, flat horizon and cloudless sky one can catch it — in New York City it sets at 7:52 p.m. on Oct. 2, a bit more than an hour after sunset at 6:35 p.m.
By about 8 p.m. Saturn will be visible in the southeast, about 25 degrees above the horizon in New York City. The planet reaches its highest altitude of 41 degrees at about 11:12 p.m. local time and it sets at 4:45 a.m. Oct 3.
Jupiter rises at 10:02 p.m. local time in New York, so the planet is visible for most of the night as it tracks across the southern half of the sky. The planet gets to its highest point (called crossing the Meridian or transiting) at 5:28 a.m. Eastern Time on Oct. 3, about 72 degrees high. The planet sets during the day; at 12:53 p.m. on Oct. 3.
Mars rises at 11:46 p.m. Oct. 2 and reaches an altitude of 66 degrees by 6 a.m. Oct. 3., as the sky is getting lighter (sunrise in New York is at 6:55 a.m.)
The timing of planetary rising and setting roughly tracks latitude; the observing conditions will be similar in cities such as Boston, Chicago, Denver or Sacramento; the local times will be similar (for example, on Oct. 2 Jupiter rises at 9:53 p.m. in Chicago and 10:09 p.m. in Denver).
For Southern Hemisphere sky-watchers the situation will differ, as the sky is "reversed." Venus is much easier to see from Southern Hemisphere locations; the planet sets at 10:18 p.m. in Santiago, Chile; sunset is at 7:46 p.m. on Oct. 2,; by 8 p.m. Venus will be 27 degrees high in the west.
Jupiter rises at 1:20 a.m. in Santiago, Chile on Oct. 2 and transits at 6:18 a.m. local time, when it is about 34 degrees above the northern horizon about an hour before local sunrise at 7:17 a.m. Saturn, which rises in the afternoon 5:35 p.m. local time; sunset is at 5:45 p.m. The planet transits at 11:59 p.m. at an altitude of 65 degrees.
Mars rises in Santiago at 3:07 a.m. on Oct. 2. With sunrise at 7:17 a.m. the planet is visible for about two and a half hours before the sun drowns it out.
And if you want to photograph the night sky, we have tips for how to shoot the night sky and how to photograph the planets, as well as guides to the best cameras for astrophotography and best lenses for astrophotography.
Stars and constellations
From mid-northern latitudes in early October, the summer constellations of the zodiac — Sagittarius, Ophiuchus and Scorpio — are exiting the sky to make way for the fall groupings of stars. By 8 p.m. Sagittarius is low in the south-southwest; Scorpius is setting and half below the horizon. The Summer Triangle, consisting of Vega, Altair and Deneb is near the zenith; Vega is the highest of the three stars with Deneb to the left and Altair towards the horizon.
Turning northwards, one will see the Big Dipper close to the horizon, the dipper appearing right side up (the bowl facing upwards). One can use the pointers, stars named Dubhe and Merak on the right side — the "front" of the bowl — to find Polaris, the pole star. Dubhe is the uppermost star; Merak is below it.
Polaris is the brightest star in Ursa Minor, the Little Bear, and if the sky is dark and one is away from city lights the curve of the Little Dipper's handle is easier to see. If one continues the line from the Big Dipper through Polaris, one reaches Caph, or Beta Cassiopeiae. Along with four other bright stars it forms Cassiopeia, a "W" shaped constellation. Between Cassiopeia and Ursa Minor is Cepheus, the King, Cassiopeia's husband. Cepheus' brightest stars form a triangle atop a square; rather like a man wearing a pointed cap. Below Cassiopeia is Perseus, the hero, rising in the northeast.
Looking from the bottom of the "W" of Cassiopeia south (this will be to the right if one is observing before about 10 p.m. facing east) one encounters the two long curving lines of stars that mark Andromeda, Cassiopeia's daughter. If one follows the stars of andromeda upwards and to the right, one reaches Andromeda's head, which is part of an asterism called the Great Square. One corner of the square is Andromeda's head, while the other three are the wing of Pegasus.
As the night progresses and one looks to the northeast, one can see Capella; the star rises at 7:30 p.m. but by 10 p.m. is high enough to see more easily. Capella is the brightest star in Auriga, the Charioteer. The constellation Cetus is also above the horizon — Cetus is often depicted as a whale, and its name is related to the word cetacean, which zoologists use to describe the order of mammals that includes whales, dolphins and porpoises. Looking southwards (to the right) of Cetus and closer to the southern horizon one can see Fomalhaut, the brightest star in Piscis Austrinus, the Southern Fish. Fomalhaut is a first-magnitude star that is also one of the sun's closer neighbors, 25 light years away.
In the Southern Hemisphere, sunsets are later as the austral summer approaches so the sky doesn't get really dark until about 9 p.m. Observers there will see the Southern Cross low in the southwest, just underneath Hadar and Rigil Kentaurus, which one can find by following the "spar" of the cross to the north (upwards from the horizon). Turning left and looking southeast, one will see Achernar, the end of Eridanus the River, about 37 degrees high. If one looks in the other direction, towards the west, one can see Antares, the heart of Scorpio (which is below the horizon in mid-northern latitudes) — one can find it because Venus, the brightest planet, will be below it. Scorpio is "upside down" — the claws of the Scorpion point to the horizon, and the tail curves toward the zenith, making a fishhook shape that ends about 60 degrees above the horizon. Above Scorpio is the teapot shape of Sagittarius.
