The new moon arrives on Sunday (Aug. 8), and three days later a thin crescent moon will pass Venus in the evening sky. It also comes just as the Perseid meteor shower gets more intense.
Because the four-day-old moon will not be very bright, skywatchers don’t need to worry about it washing out the fainter meteors when the shower peaks on Thursday (Aug. 12). It also sets that night by about 10:30 p.m. local time in mid-northern latitudes, leaving the meteors to shine most of the night.
The moon is officially new at 9:50 a.m. EDT (1350 GMT) on Sunday. A new moon means the moon is directly between the sun and Earth. Technically, both objects are in conjunction, or on the same north-south line that passes through the celestial pole, near the star Polaris. (The term is also applied to other celestial bodies, such as planets).
The timing of the lunar phases depends on where the moon is relative to the Earth, so it occurs at the same time all over the world — the only differences being due to what time zone you are in. In Melbourne, Australia, for example, the new moon occurs at 11:50 p.m. on Aug. 8, and in London it is at 1:50 p.m.
Since the new moon is between Earth and the sun, it is invisible unless there is a solar eclipse. Eclipses don’t happen every new moon because the moon’s orbit is tilted by about 5 degrees relative to the plane of the Earth’s orbit. Most of the time the new moon is offset from the sun (from the point of view of Earthbound observers), rising and setting at around the same time. The next solar eclipse isn’t until Dec. 4, 2021.
On Monday (Aug. 9) the moon is in conjunction with Mars. The conjunction occurs at 8:42 p.m. EDT (0042 Aug. 10 GMT), according to the skywatching site In-The-Sky.org.
The moon will be a very thin crescent, barely a day and a half old, and it will be about 4 degrees north of the Red Planet, or, as seen from mid-northern latitudes, to the right and slightly above it.
But from New York City the pair will be near-impossible to see; sunset is at 8:01 p.m. local time (per Time and Date) and the moon will only be at an altitude of about 11 degrees, according to Heavens-Above.com calculations. Mars will only be about 9 degrees above the horizon.
Spotting the moon will be challenging even with a clear sky and obstruction-free horizon. By the time the sun is 6 degrees below the horizon — the end of civil twilight, when some jurisdictions turn the streetlights on — the moon will only be 5 degrees high and Mars will be at about 3 degrees.
(Warning: While spotting the moon so soon after the new phase can be a fun challenge — it was and is important for people who use lunar calendars such as observant Jews and Muslims — pointing binoculars or a telescope to an object near the sun is a very dangerous thing to do; the sun’s light is concentrated and can burn one’s retinas, even at sunset. Such damage is permanent).
Visibility improves greatly as one moves south. In Miami, for example, the sun sets at 8 p.m. local time, while the moon will be about 14 degrees in altitude and Mars will be at about 13 degrees; by 8:25 p.m., when civil twilight ends, they will still be about 8 degrees above the horizon and much easier to see.
Southern Hemisphere observers will have the best chances to see the conjunction of Mars and the moon (even though the hour of the day is less favorable) because it is now the austral winter and the ecliptic — the path the sun and planets follow in the sky — is higher in the sky at night.
In Cape Town, for example, the conjunction occurs at 2:42 a.m. local time, so the closest passage of the moon and Mars isn’t visible. However, at sunset, which occurs at 6:12 p.m. local time, the moon will be at an altitude of 10 degrees while Mars will be at 17 degrees. That means that by about 6:38 p.m., the end of civil twilight, the moon will still be about 5 degrees (or 10 lunar diameters) high, and Mars will be at about 12 degrees.
The next conjunction will happen only two days later, on Wednesday (Aug. 11), as the moon passes Venus, about 4 degrees north of the planet. Both will be visible in the evening sky — though the actual conjunction will be at 2:59 a.m. EDT (0659 GMT).
Sunset in New York City is at 7:58 p.m. local time, and the crescent moon will be about 22 degrees high; Venus will be 16 degrees up and to the right of the moon (and closer to the sun). About a half-hour later both will still be visible with Venus still approximately 11 degrees in altitude and the moon at 17 degrees. Venus sets at 9:25 p.m. in New York.
As with the Mars conjunction, those farther south will have an easier time. For example, Miami’s skywatchers will see the sun set at 7:59 p.m. local time and Venus will be a full 24 degrees above the horizon, and the moon will be 30 degrees up. Venus will set at 9:46 p.m. local time.
In Cape Town, the conjunction occurs during the day, at 8:59 a.m. At sunset, which is at 6:13 p.m., the moon is 53 degrees high and Venus is at 47 degrees; that means that by 6:43 p.m. when the sky is dark enough to begin seeing stars the two will still be well above the horizon (about 40 degrees high). As the Southern Hemisphere sky appears “upside down” the Moon will be slightly above and to the right of Venus.
The actual moment of the Venus conjunction will be visible from time zones east of Australia; for example in Christchurch, New Zealand the sun sets at 5:39 p.m. local time and the conjunction is at 6:59 p.m. The moon will be 25 degrees above the horizon and Venus will be at 30 degrees. The moon sets first at 8:25 p.m. and Venus at 8:36 p.m.
(To find out when the planets, moon and sun rise and set from your specific location, check out Time and Date’s night sky calculator.)
On Sunday night (Aug. 8) in mid-northern latitudes Mercury will be lost in the sun’s glare; in New York City at sunset the planet is only 4 degrees above the northwestern horizon.
Jupiter and Saturn, by contrast, will be visible almost all night. Saturn rises at 7:41 p.m. local time in New York, followed by Jupiter at 8:35 p.m., so as the sky gets fully dark one will see them low in the southeast by about 9 p.m., with Saturn at about 17 degrees and Jupiter at 5 degrees altitude.
In the Southern Hemisphere, Jupiter and Saturn will be higher in the sky; from Melbourne at 9 p.m. on Aug. 9 Saturn will be at about 47 degrees and Jupiter at 29 degrees above the horizon in the northeast.
August is the time for the Perseid meteor shower. The Perseids, so named because the radiant (the point in the sky they seem to originate from) is in the eponymous constellation, Perseus. In much of the Northern Hemisphere that point is circumpolar, which means it never sets. This makes for good meteor watching almost all night.
While the shower is active starting in late July and through Aug. 24, the peak of activity is around Aug. 12, and the new moon is just four days before that. A new moon means there is nothing in the sky bright enough to wash out the meteors, so even from suburban locations it can be possible to see them — though your best bet is always to find a place away from city lights.
By about 9 p.m. local time on the night of the new moon, Perseus will be rising in the northeast; its brightest star Mirphak can be found by looking for the Big Dipper and the North Star Polaris. Look to the right of Polaris and find the “W” shape of the constellation Cassiopeia. Mirphak will be below Cassiopeia and the radiant of the Perseids will be a few degrees above Mirphak.
That said, to see meteors — there will be about two per minute — the best strategy is to look about 30 degrees away from the radiant. That radiant point reaches its highest point in the sky at about 7 a.m. your local time, so the most meteors are usually visible after midnight (this is also when the Earth is “facing” the stream of dust and debris that makes meteors).
Meteors are small particles of dust left behind by comets. The Perseids parent body is comet Swift-Tuttle, which makes a 133-year circuit around the sun. Its last appearance near Earth was in 1992; when it could be seen with binoculars and telescopes; it will be back in 2126.
As the “comet crumbs” enter the atmosphere and burn up, this creates meteors, commonly known as “shooting stars.” Most of the ones we see at night are the size of grains of sand; the glow is caused by the heat as the meteor collides with the upper atmosphere some 60 miles (100 kilometers) from the Earth’s surface.
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