The moon is new at 4:17 a.m. (0817 UTC) on August 27 for observers in the Eastern Daylight Time zone, according to the U.S. Naval Observatory (opens in new tab). A new moon occurs when the Sun and moon are in conjunction, on the same north-south line that passes through the celestial pole, near the star Polaris. (The term conjunction is also applied to other celestial bodies, such as planets). This also puts the moon directly between the sun and Earth.
Lunar phases’ timing depends on where the moon is relative to the Earth, so they occur at the same time all over the world, with any differences due to one’s longitude (and time zone). For example, in Sydney, Australia the new moon occurs at 6:17 p.m. on August 27, as there is a 14-hour time difference between eastern Australia and the east coast of the U.S.
New moons are not visible unless there is an eclipse; eclipses don’t happen every new moon because the orbit of the moon is tilted by about 5 degrees relative to the plane of the Earth’s orbit, and the node — the point where the orbits intersect — moves relative to the Earth’s surface. So the moon’s shadow “misses” the Earth most of the time. (The next solar eclipse isn’t until October 25, 2022).
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Mercury is at greatest eastern elongation on the same day the moon is new at 5:47 a.m. Eastern Time (opens in new tab). As measured along the planet’s orbit (as projected on the sky) Mercury will be 11 degrees east of the sun, so it will be above the horizon after sunset. The planet’s elevation above the horizon will vary with latitude; from New York City it will be at about 9 degrees at 7:36 p.m. (sunset). That means the planet won’t become visible until at least a half hour later, but by about 8 p.m. it will only be about 4.4 degrees high — to see it at all will require a flat horizon with no obstructions (or clouds).
As one moves south, seeing Mercury gets easier. From Miami, the planet’s altitude at sunset on August 27 (which is at 7:45 p.m.) is about 15 degrees, and by the start of nautical twilight (when the sun is between 6 and 12 degrees below the horizon) at 8:08 p.m. local time, Mercury will still be 10 degrees above the western horizon, and bright enough that it should start to become visible against a darkening sky.
From the Southern Hemisphere, Mercury is higher in the sky. In Buenos Aires, the sun sets at 6:31 p.m. local time on Aug. 27, while Mercury sets at 8:39 p.m. By 7 p.m. the planet is 20 degrees high in the west, and more easily visible than in the northern latitudes.
After the new moon, on August 29 at 6:51 a.m. Eastern Time, the moon will be in conjunction with Mercury (opens in new tab). From mid-northern latitudes the two-day-old moon and planet pair won’t be visible (at least not together) — the sun sets in New York City at 7:34 p.m. and Mercury will only be about 8 degrees above the western horizon, lost in the glare of the sun. By the time the sky starts to get dark (about 30 minutes after sunset) the planet will only be about 4 degrees high.
This is another situation where the more southerly sky watchers have an advantage. In Miami, the moon (a thin crescent) will appear above Mercury, which becomes visible as the sky darkens. By 8 p.m., about 15 minutes after sunset, Mercury will be about 11 degrees high and the moon at about 16 degrees, and the planet will just start to be visible. In Buenos Aires sunset is at 6:31 local time and by 7 p.m. the pair will be at about 20 degrees, with the moon to the right of Mercury as seen from Earth.
For the mid-northern latitudes, the other four visible planets will make a kind of line across the sky in the hours before dawn. On the night of Aug. 27 in New York City Mercury sets at 8:24 p.m. local time (times will be similar in cities such as Chicago, Denver, Madrid, Istanbul, and Rome). As the sky gets darker one will see Saturn in the east; the planet rises at 7:02 p.m. Eastern Time, and by sunset, Saturn will be 6 degrees high in the east, in the constellation Capricornus. Capricornus is not a bright constellation, so from city locations, the planet will probably be visible before the stars of the constellation are, likely by about 7:45 p.m. to 8 p.m. since it is on the other side of the sky from the sun, the glare will be less.
Saturn is followed by Jupiter, which rises at 8:55 p.m. (opens in new tab) when the sky is fully dark. Jupiter will be in the constellation Cetus. Like Capricorn, Cetus contains few bright stars, so Jupiter becomes obvious because of the contrast.
Mars rises just before midnight on Aug. 27, at 11:29 p.m. In the constellation Taurus, the Red Planet will appear to be above the star Aldebaran as it gets higher in the east. Aldebaran will appear somewhat less reddish (most people see it as yellow-orange). One can also follow the rule that stars twinkle and planets do not; Mars will be the steadier light.
Venus rises at 5:05 a.m., about an hour and 13 minutes before the sun (which rises at 6:18 a.m. on Aug. 28 in New York). Venus won’t get very high in the sky by sunrise, when it reaches about 13 degrees above the horizon just north of east, but it is so bright that it is often visible even as other stars fade from view. By about 3 a.m. local time one will be able to see Mars about 28 degrees high in the east.
Constellations: Northern Hemisphere
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For Northern Hemisphere sky watchers August is when the summer constellations dominate the first half of the night, and the autumn stars begin to appear after midnight, followed by some winter stars in the predawn hours.
By 10 p.m. the Summer Triangle is high in the eastern sky; the “top” star is Vega, the brightest star in Lyra the Lyre, and it is almost at the zenith (about 79 degrees above the horizon). The other two stars in the Summer Triangle are of Deneb and Altair, both of which are east (to the left) of Vega. Below Altair (looking further south) one can see the teapot shape of Sagittarius almost due south and Scorpius to the right of it, low in the southwest.
Looking north (again at about 10 p.m. from mid-northern latitudes) one will see the Big Dipper to the left (west) and below Polaris. If one imagines the sky as a huge clock face with Polaris at the center, the Dipper will be at approximately the 8 o’clock position. Follow the “pointers” (the two stars in the front of the bowl of the Dipper, Dubhe and Merak) to Polaris. Two stars can be seen to the left of Polaris, forming the “bowl” of the Little Dipper (otherwise known as Ursa Minor, the Little Bear), called Kochab and Pherkad. They are also known as The Guardians and in ancient times the celestial pole was closer to Kochab. As the Earth’s axis changed direction, a process called precession, the celestial pole moved closer to Polaris, which took on its current navigational role in the medieval period.
From the Big Dipper’s pointers, continuing straight past Polaris one encounters Cepheus, the king, and just below Cepheus is the “W” shape of Cassiopeia. Cepheus and Cassiopeia are the legendary king and queen of Ethiopia, the parents of Andromeda who Perseus saved from a sea monster. Perseus is just below Cassiopeia, near the northeastern horizon.
In the other direction, follow the handle of the big dipper and “arc to Arcturus,” the brightest star in Bootes, the herdsman. Turning south, one sees Scorpius again, and the bright red star Antares. In darker sky locations looking up (north) from Scorpio one sees Ophiuchus the healer, who appears to be stepping on Scorpius’ head.
Constellations: Southern Hemisphere
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In the mid-southern latitudes, the days are getting longer, as the winter solstice there was on June 21 — but it is still late winter there, so sunsets will be relatively early. At the latitude of Cape Town, the sun sets at about 6:24 p.m. local time, and in Sydney, sunset is at 5:33 p.m. local time on August 27.
So for antipodeans in mid-southern latitudes, the sky is dark by 8 p.m. At that point in the northeast one sees Vega and Altair, two of the stars in the Summer Triangle — since it is “upside down” Altair rises before Vega does, and both are lower in the sky than in the Northern Hemisphere. Turning towards the south (to the right) one will see Fomalhaut, the brightest star in Piscis Austrinus, the Southern Fish, about 24 degrees high. Keep turning right and one sees Achernar, the star that marks the end of Eridanus, the River, which starts near the foot of Orion — Achernar isn’t often visible to Northern Hemisphere sky watchers.
The Southern Cross is high in the south-southwest — the brightest star, Acrux, is about 34 degrees above the horizon by 8 p.m. It forms something of a cluster of bright stars; the Cross is a compact constellation and it is relatively close to Alpha Centauri, our nearest stellar neighbor and the alpha star of Centaurus, the Centaur. At this point, Alpha Centauri, also known as Rigil Kentaurus, appears above the Cross. Just below Alpha Centauri is Hadar, the second-brightest in the Centaur, and between Alpha Centauri and the Cross.
Turn your gaze upwards, towards the zenith, and at an altitude of 71 degrees, one sees Scorpius and Antares.
The Southern skies have no pole star; the closest thing is the faint constellation Octans, the Octant, and Chameleon, but both are faint. To find the South Celestial pole one method is to use the Southern Cross, and draw a line to Achernar; about halfway down that line and just above it will be the pole.
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