The new moon occurs Tuesday (Feb. 1), at 12:46 a.m. EST (0546 GMT), a day before the moon makes a close approach to the planet Jupiter in the night sky.
New moons occur when the sun and moon share the same celestial longitude, a projection of the Earth’s own longitude lines on the celestial sphere. This happens when the moon is directly between Earth and the sun; such alignment is also called a conjunction. The sunlit side of the moon faces away from us at the new moon, so unless there is a solar eclipse — the moon passing directly in front of the sun — new moons are invisible to earthbound observers.
The timing of new moons and other lunar phases is the same over the entire Earth, with the differences being a result of time zones. While the new moon occurs in New York just after midnight, in Melbourne, Australia it is on Feb. 1 at 4:46 p.m. local time.
In many traditional calendars, new moons mark the first day of the month. Hebrew, Muslim, and Chinese lunar calendars all reckon their months from the new moon. For example, the first day of the Hebrew month of Adar is on Feb. 1, and the Muslim month of Rajab starts on Feb. 2. The Islamic calendar starts the new month a day after the “official” new moon because Islamic astronomers had to rely on visual observations — you can’t see the moon until it emerges from the sun’s glare a day or so after the new moon. It’s also the case that the new moon occurs later in the day, at about 7:46 a.m. on Feb. 1.
On the night of the new moon, just after sunset (which happens at 5:13 p.m. in New York), Jupiter will still be visible in the southwest. Saturn sets only five minutes after the sun does; it will be effectively invisible due to the sun’s bright glare and the planet’s proximity to the horizon. Mars, meanwhile, will rise in the predawn hours, at 5:03 a.m. local time in New York. Venus rises about 10 minutes before Mars does, and the “morning star” will be a bright presence in the east; it is so bright that it is often one of the last night sky objects to disappear as the sun rises.
A day after the new moon, our moon will enter conjunction with Jupiter, which occurs at 4:10 p.m. EST (2110 GMT), according to the skywatching site In-The-Sky.org. At that time, the waxing crescent moon will pass just over 4 degrees to the south of Jupiter. Both should become visible by about 5:30 p.m. in New York; Jupiter sets there by 7:11 p.m. local time.
If you have a telescope or binoculars, you might be able to catch Uranus, especially from a dark-sky location. Uranus usually shines at a brightness of magnitude 5 or 6, which is about the limit of visibility for even a keen-eyed person. To find it one can trace a line between Alpha Ceti (Menkar), the second-brightest star in the constellation Cetus, the whale, and Beta Arietis (Sheratan), the second-brightest star in the constellation Aries. Uranus is near the line between the two.
Stars and constellations
By about 7 p.m. the Big Dipper will be rising in the northeast, with the “bowl” facing north, and the “handle” pointing to the horizon. The two stars at one end of the Dipper are Alpha and Beta Ursae Majoris, respectively called Dubhe and Merak. Those point to Polaris, the North Star. Using those same “pointers” one can go in the opposite direction, and find the constellation Leo, the lion, which will be more due east. The two stars at the back of the Big Dipper’s bowl point to the star Regulus, the brightest star in Leo. The more northerly star is called Megrez while the other is called Phecda. On Feb. 1 the Lion will be half above the horizon at sunset; the constellation won’t be completely visible until about 9 p.m. local time.
By about 9 p.m., from mid-northern latitudes one will see Canis Major, Orion and Taurus in a rough line from south-southeast as one’s point of view approaches the zenith (the point in the sky directly overhead). All three will be well above the horizon with Orion marking due south. Orion’s famous belt (consisting of the stars Alnilam, Alnitak and Mintaka) is visible even from city locations, as is Sirius, the “Dog Star” in Canis Major.
As the night progresses observers can watch the constellation Virgo rise by about midnight. The Big Dipper can help here; at that point the Dipper will be approaching the “upside down” position, and using the handle one can “arc to Arcturus” by drawing a sweeping arc to Arcturus, an orange-yellow star in Boötes, the herdsman, and then keep going to reach Spica, the brightest star in Virgo.
In the Southern Hemisphere, sunset is later, as it is summer. In Buenos Aires the sun doesn’t set until about 7:59 p.m. By 9 p.m., when it is fully dark, the Southern Cross will be rising in the southeast. Just below it is the constellation of the Centaur, containing Alpha Centauri, our nearest stellar neighbor. If you follow the Milky Way up from the horizon, you’ll encounter the three constellations that make up Argo, the ship: Puppis, the deck; Vela, the sail; and Carina, the keel. Even if one can’t see the Milky Way because of city lights, the group of relatively bright stars in the region is noticeable.
Canopus is the brightest star in Carina, and it is known for being one of the most luminous stars in the solar neighborhood. It is 310 light-years away and magnitude -0.76, making it some 10,000 times as bright as the sun, according to observations by the European Southern Observatory.
From Southern Hemisphere locations one can use the Southern Cross to locate Corvus, the crow, which will be rising in the east just south of Leo when the Cross is high in the sky. Going in the other direction, towards the west, one can see the Small and Large Magellanic Clouds, two satellite galaxies of the Milky Way, provided the sky is relatively free of city lights.
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