September’s new moon will partially eclipse the sun, though the eclipse will only be visible from the southern Pacific Ocean and Antarctica.
A new moon is when the moon shares the same celestial longitude as the sun; the two bodies are said to be in conjunction. This occurs about every 29.5 days. The exact moment of this months’ new moon occurs today (Sept. 21) at 3:54 p.m. EDT (1954 GMT).
This also puts the moon between the sun and Earth, and if the new moon is perfectly lined up with the sun, we see a solar eclipse. Solar eclipses aren’t visible from everywhere on Earth because the moon’s shadow only covers a small part of the Earth’s surface, so while solar eclipses happen about twice a year, a given point on Earth will be in the moon’s shadow a lot less often.
Solar eclipses can be either partial or total; this one is a partial eclipse so only a portion of the sun is covered by the moon; the sun appears to be a crescent or to have a “bite” taken out of it. One should be very careful observing solar eclipses; use of eclipse glasses or specialized solar filters is a must; and never look at the sun through any kind of optical aid (such as a camera lens, binoculars or telescope) without a filter; the result can be permanent blindness from retinal burns.
In this case, the limits of the partial eclipse visibility extends from the southern atolls of Kiribati and Fiji in the north, French Polynesia and the Antarctic Peninsula in the east, and the eastern coasts of Australia and Tasmania in the west, (though Australians and Tasmanians will only see a tiny sliver of the sun covered). Southern New Zealand allows for observing the deepest eclipse; one can do so from the southern half of Stewart Island.
Oban, New Zealand, is the only town on Stewart Island, and there the eclipse starts at 6:10 a.m. New Zealand Standard Time on Sept. 22. Sunrise in Oban is at 6:37 a.m., so the eclipse starts while the sun is below the horizon. As the sun rises, one will see a crescent as the moon is already covering the upper-left portion of the sun. Maximum eclipse occurs at 7:14 a.m. – the sun will still be only about 6 degrees high in the east – and the eclipse ends at 8:23 a.m. About 73 percent of the sun’s disk will be covered at maximum eclipse.
In less remote parts of New Zealand such as Christchurch, up to 69 percent of the sun will be covered. As in Oban, the eclipse starts at 6:03 a.m., before the sun rises at 6:19 a.m. At that point the moon is covering a small part of the upper-left side of the sun (the northern side). Maximum eclipse is at 7:08 a.m. local time, and the moon will appear to have shifted to the other side of the sun even as it covers more of it; one will be able to see the “Devil horns” shape as the sun will appear to be a crescent with the points facing upwards. The eclipse ends at 8:18 a.m.
For observers in Fiji, only about 27 percent of the sun will be covered; in Suva (the largest city) the eclipse starts Sept. 22 at 5:31 a.m. local time (before sunrise). Sunrise is at 5:56 a.m. and the top part of the sun will be obscured; the maximum eclipse is at 6:22 a.m. and the eclipse ends at 7:19 a.m.
Visible planets
For those that can’t see the eclipse, the night of the new moon offers some visible planets, each following the other in the sky as the night progresses. In New York City (other locations in mid-northern latitudes will have similar times) sunset on Sept. 21 – the day before the equinox – is at 6:54 p.m. EDT. The end of civil twilight, when the sky gets dark enough that streetlights begin to turn on, is at 7:21 p.m. If one is near a flat, unobstructed horizon and has a clear sky, it’s just possible to catch Mars, which will be only about 7 degrees high in the southwest. The planet isn’t bright enough to be very distinct against the sky, so observing the planet before it sets at 8:05 p.m. EDT. The red planet will be much more visible later in the year as it emerges from the sun’s glare in the evenings.
Jupiter rises next, at 12:59 a.m. Sept. 22. Jupiter is in the constellation Gemini, the Twins, and will be to the right of the two brightest stars in the constellation, Castor and Pollux. Jupiter will be brighter than either of those two stars, which will be on the left side of the planet. Jupiter transits at 8:22 a.m., so it will be lost in daylight before it gets there, but by 6:00 a.m. the planet will be a full 54 degrees high in the east-southeast.
After Jupiter we see Venus, which rises at 4:31 a.m. EDT on Sept. 22. Venus is the third brightest object in the sky after the sun and moon, so it will be quite obvious even if it is close to the horizon. Sunrise is at 6:44 a.m. EDT and Venus will be visible until about 6:30 a.m., when it will be about 21 degrees high in the east.
Nearer the equator, some planets become easier to see. In Bogota, Colombia, for example, Mars sets at 7:41 p.m. local time, and sunset is at 6:13 p.m. The planet is still about 16 degrees above the western horizon by 6:30 p.m. when the sky is getting dark, so it spends a bit longer out of the solar glare than in locations further north. Saturn, meanwhile, rises at 5:49 p.m. – still in daylight – and about a half hour after sunset is 13 degrees high in the east. The planet transits at 11:49 p.m. and is 82 degrees high—almost directly overhead.
Jupiter rises at 1:13 a.m. local time on Sept. 22, and by 2:30 a.m. one can see it in the east about 17 degrees above the horizon. Venus follows at 4:07 a.m. and is about 20 degrees high in the east by 5:30 a.m. (sunrise in Bogota is at 5:46 a.m.).
Southern Hemisphere locations will have the easiest time spotting Mars in the evening. In Santiago, Chile, sunset on Sept. 21 is at 7:39 p.m. local time and civil twilight ends at 8:03 p.m. Mars sets at 10:02 p.m. so by 8:15 p.m. it will still be about 21 degrees high in the west.
As the sky gets dark, Saturn will be in the east; the ringed planet rises at 7:26 p.m. – before sunset – but by 8:30 p.m. Saturn is 12 degrees above the eastern horizon. The planet transits at 1:36 a.m. Sept. 22, and will be 59 degrees high in the north; nearly two thirds of the way to the zenith.
Jupiter rises in Santiago at 4:07 a.m. on Sept. 22 and from mid-southern latitudes it will appear to be above and to the right of Castor and Pollux, with Pollux appearing almost directly below the planet. By 5:30 a.m. it is 14 degrees high in the northeast.
Venus rises at 6:27 a.m., so it is only visible for a short time – sunrise is at 7:22 a.m. and the planet is only 10 degrees high by then; bright as it is it will be difficult to spot without a clear and unobstructed horizon.
Constellations
In late September, by about 8:30 p.m., one can look almost due west to see Arcturus, a bright orange-white star, about 20 degrees high. Arcturus is recognizable because of its color – it can look distinctly orange, and from mid-northern latitudes Mar has already set, so there’s no confusing the two. If one looks to the right, towards the north, one will see the Big Dipper, the asterism that is part of Ursa Major, the Great Bear.
Looking to the left of Arcturus (slightly southward) and upwards, one can see a bright star that is the center of a small arc of fainter stars; this is the constellation Corona Borealis, the Northern Crown, and its bright star is called Alphecca.
Going back to the Big Dipper, which will look almost horizontal, one can use the “pointers” — the two stars at the front of the bowl (the right side) to find Polaris, the Pole Star. The pointers are called Dubhe and Merak, with Dubhe being the one closer to Polaris. Polaris will be upwards; and from a darker-sky location one can see to the left of Polaris the two fainter stars called the Guardians, which are one side of the bowl of the Little Dipper. The lower one is called Kochab and the upper one Pherkad.
If one continues the line from the Dipper through Polaris, one sees Cepheus, the legendary king of Aethiopia. Just below that is the “W” shape that represents Queen Cassiopeia, his wife. Both are towards the northeast and relatively high in the sky; about halfway to the zenith. Cassiopeia, Cepheus, and the Big Dipper are all known as circumpolar stars – they never truly set for many Northern Hemisphere observers. As one moves northwards, more of the southern stars move below the horizon and aren’t visible at all, but more of the constellations in the northern half of the sky become circumpolar. The same is true as one moves into the Southern Hemisphere, though it is the northern stars that go below the horizon and a different set of constellations that become circumpolar.
Looking further eastwards and towards the horizon, using the pointed parts of the “W” one can see a long arc of four medium-bright stars that form part of the constellation Andromeda, Cassiopeia’s daughter. The rightmost point of the arc (it looks like a long smile) is part of the Great Square, which will look like it is standing on one corner. That square is the wing of Pegasus, the winged horse.
On this night the Summer Triangle – an asterism made up of Deneb, Altair and Vega – is almost directly overhead. It’s recognizable as the three stars are bright enough to see even in a city location; Altair, the “eye” of Aquila, the Eagle, is the southernmost part of the triangle; one can imagine it as the tip of a triangle pointing south. From Altair, one can look straight up and see Deneb on the left and Vega on the right to complete the Triangle. Deneb is the tail of Cygnus, the Swan.
Vega is the brightest star in Lyra, the Lyre. The constellation Cygnus forms a cross shape and it is sometimes called the Northern Cross; if one follows the long axis of the cross roughly towards Altair, one reaches the star Sadr, the center of the cross, and then Albireo, the “head” of the Swan.
Drawing a line between Deneb and Altair takes you to Sagittarius; close to the horizon in the south. Sagittarius has a distinct “teapot” shape of seven stars. Scorpius (the Scorpion) will be nearly setting, though the heart of the Scorpion, Antares, is still just high enough to see if the horizon is clear of obstructions; it is only about 9 degrees high from the latitude of New York.
Above Scorpius one can see Ophiuchus; the Serpent Bearer. To find it, look for Antares, and then upwards from the horizon; one should see a large rectangle of fainter stars with a short horizontal side and longer vertical ones; that is the body of Ophiuchus, and above the rectangle is a star that makes an “A-frame” shape, which is his head. Ophiuchus is sometimes called a 13th constellation of the zodiac, because the constellation’s modern borders mean the sun and planets often pass through it.
Constellations visible in the Southern Hemisphere on Sept. 21 at about 9 p.m. local time will include the Southern Cross, Centaurus the Centaur, and the Southern Fish. From mid-southern latitudes such as Cape Town or Santiago, Chile, or Melbourne, Australia, The Southern Cross (officially called Crux) is in the southwest, about 21 degrees above the horizon. It’s a compact group and the bottom of the cross, marked by Acrux, faces roughly towards the Southern Celestial Pole (in this case the bottom of the cross is to the left, because the Cross will appear sideways). Above the Cross are two bright stars; the first one (as one moves upwards) is Hadar, and the second is Rigil Kentaurus, otherwise known as Alpha Centauri. These are sometimes taken to be the front hooves or legs of the Centaur.
Turning towards the southeast (to the left) one will see a bright star that at 9 p.m. local time will be at about the same altitude as the Cross (imagine drawing a straight horizontal line almost halfway across the sky). This is Achernar, the end of Eridanus, the River. The River extends below the horizon (the rest of it doesn’t rise until later) but the other end is near the foot of Orion.
If one continues turning left (towards the east) and upwards, about halfway to the zenith, one encounters Fomalhaut, the brightest star in Piscis Austrinus, the Southern Fish. Fomalhaut is west and south of Saturn, putting it above and to the right of the ringed planet. From the Northern Hemisphere it is always close to the horizon and difficult to see but in the Southern Hemisphere it gets much higher in the sky.
Turning to the north (left from Fomalhaut and Saturn), one can see the Summer Triangle, but from below the equator it is “upside down” with Vega closer to the horizon, about 16 degrees high (this will change a bit depending on one’s exact latitude), with Altair above and to the right. Deneb is hard to see from the southern latitudes; it will be to the right of Vega but only about 9 to 10 degrees above the horizon.
In the high western sky  — above Mars  — one can spot an upside-down Scorpius, which in the southern skies faces towards the horizon and is much higher, with Antares about 53 degrees high if one is at the latitude of Santiago, Chile or Sydney, Australia. Sagittarius is also high in the sky; almost directly overhead.
