The new moon occurs Friday (May 22), at 1:39 p.m. EDT (1839 GMT), the same day that Venus and Mercury make a close approach, according to NASA.
A new moon occurs when the moon is between the sun and Earth, and the two bodies share the same celestial longitude. (Celestial longitude is a projection of the Earth's own longitude lines on the celestial sphere). Such alignment is also called a conjunction. Because the sunlit side of the moon is facing away from us, new moons are generally invisible from Earth unless the moon passes in front of the sun, as happens during solar eclipses.
At about 5:37 a.m. EDT (0937 GMT) on May 22, Venus and Mercury will share the same celestial longitude as well. For people in New York City the moment of conjunction won't be visible, since both planets will be below the horizon. By the evening they will be close together (just under two lunar diameters apart). At about 8:30 p.m. local from New York City, they will appear side-by-side, both in the constellation of Taurus, the bull. The sun sets at 8:12 p.m. local time that day, or about an hour and a half before Venus and Mercury dip below the northwest horizon.
Venus should be quite visible, as it is the brightest object in the night sky, shining at magnitude -4.1. (Magnitude is a measure of brightness used by astronomers, with lower numbers denoting brighter objects and negative numbers indicating exceptionally bright objects.) Mercury will be harder to see — it is magnitude -0.5, a bit brighter than the star Vega — but once you catch Venus you can use the brighter planet to orient yourself to find Mercury, which will be to its left. Both planets will be relatively close to the horizon, only about 13 degrees above it (or a bit more than the width of a clenched fist at arm's length).
For those in the Southern Hemisphere, the sun sets earlier as we enter austral winter, but the two inner planets will be harder to see. In Melbourne, Australia, the new moon occurs at 3:38 a.m. local time on May 23. The conjunction of Venus and Mercury occurs at 7:37 p.m. local time on May 22. Even though the sun sets at 5:13 p.m., by 5:30 p.m. Mercury and Venus will only be about 6.4 degrees and 4.6 degrees above the northwestern horizon, respectively, with Mercury above and to the right of Venus. The planets will set shortly after 6 p.m. local time.
Visible planets and constellations
Besides Venus and Mercury, the planets further out will still be visible in the after-midnight sky. The first to rise is Jupiter, in the constellation Sagittarius, the archer. Jupiter rises at 12:08 a.m. local time in New York City. Saturn, in the constellation of Capricornus, the sea goat, follows at 12:23 a.m.
Last is Mars, at 2:08 a.m., according to Heavens-Above.com calculations. Jupiter and Saturn will be about 23 degrees in altitude by about 3 a.m. local time and Mars will be about 9 degrees above the south eastern horizon.
For antipodeans, the three planets are easier to see, at least if you don't want to stay up late. In Melbourne, Mars rises at 12:17 a.m. local time on the morning of May 23 and 12:16 a.m. on the morning of May 24, and the sun doesn't rise on those days until 7:20 a.m., giving observers plenty of time to view the Red Planet. Jupiter and Saturn respectively rise at 9:00 p.m. and 9:24 p.m. local time, and by 11:30 p.m. Jupiter will be 28 degrees in altitude and Saturn 24 degrees, so those planets will also be easy to spot.
On the night of the new moon, observers in mid-northern latitudes will still see the spring and summer constellations becoming more prominent. By 8:30 p.m. local time in New York City, the constellation of Leo, the lion will be high in the western half of the sky.
Just above the horizon in the east will be the constellation of Lyra, the lyre, with Vega as its brightest star, and the bright star Deneb, which marks the tail of the constellation Cygnus, the swan. Both are two stars of an asterism, or star pattern, known as the Summer Triangle. The third star is Altair, which is well above the horizon by 11 p.m. The winter constellations such as Orion, Taurus, Gemini and Canis Major will all be setting by 8:30 p.m. local time and will be completely below the horizon before midnight.
In the southern latitudes, some of the same constellations that mark winter for northerners are still visible after sunset; Canis Major is still about 25 degrees above the western horizon by 8 p.m. local time. Meanwhile, high in the south the Southern Cross will be just east of the meridian, and just to its left will be the Centaurus constellation, with Alpha Centauri, our nearest stellar neighbor, marking one of the feet of the Centaur. The Scorpius constellation, which in northern latitudes is low in the sky, is "upside down" and high in the southeast.
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