Under dark skies when Cygnus is higher, sharp-eyed observers may even glimpse this object without optical aid. The nebula is also quite large, spanning some 2° by 12/3°. Located near bright Deneb, the Swan’s tail star, this beautiful emission nebula lies about 3° due east of that luminary, making it easy to find. While the Moon remains visible at night, let’s check out the Swan about two hours before dawn to explore one of its many gems: the North America Nebula (NGC 7000). The large constellation Cygnus is currently soaring through the early-morning sky. Uranus’ disk is just 4″ across, thanks to the planet’s distance from Earth: some 19.54 astronomical units (AU where 1 AU is the average Earth-Sun distance), or 1.8 billion miles (2.9 billion kilometers). It will appear as a dim, “flat”-looking star, whose edges might appear sharply defined, rather than the formless pinprick of light shown off by stars. You’ll need binoculars or a telescope to view Uranus, which glows softly at magnitude 5.8. The half-lit Moon sits just outside the perimeter of this triangle. The planet sits inside a triangle of three of the Ram’s fainter (5th to 6th magnitude) stars: Sigma (σ), Omicron, and Pi (π) Arietis. The Moon sits about 11.5° southeast of these stars, and Luna is now nearly 2° due west of distant Uranus. This constellation doesn’t have many bright stars: Hamal (magnitude 2) and Sheratan (magnitude 2.6) are the most notable. The pair are in Aries the Ram, which lies in the southwest after dark. EST, the Moon passes 0.9° north of Uranus. local time from the same location.įirst Quarter Moon occurs at 10:19 A.M. The Moon’s illumination is given at 12 P.M. *Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. Diphda gives off copious amounts of X-rays and appears to be fusing its helium into carbon as it, too, approaches the later stages of its life. This star is relatively close to Earth, just 96 light-years distant, compared with Menkar’s 220. At magnitude 2, it is brighter than Menkar, despite its Greek-letter “rank” of second. On the other side of the constellation to the southwest, marking the tail of Cetus is Deneb Kaitos (Beta Ceti), also called Diphda. Astronomers believe that Menkar, too, will become a variable like Mira, before ultimately ending its life as a white dwarf. This star is slightly younger than Mira but is now reaching the later stages of its life, no longer burning hydrogen into helium in its core. But, of course, you can pick it up with binoculars or a telescope, some 12.7° southwest of our next stop: magnitude 2.5 Menkar, Cetus’ alpha star. So, if you look for it with the naked eye tonight, you won’t see it - it’s simply too faint. So, sometimes it is readily visible to the naked eye, taking its proper place in the center of the constellation, and sometimes it appears to have vanished! In fact, Mira’s last peak, when it was brightest, was July last year, and its next is June of this year. An aging variable star, Mira changes in brightness between roughly 3rd and 10th magnitude over the course of just under a year (330 days). One such star is Mira, also cataloged as Omicron (ο) Ceti. This large constellation - the fourth largest of all 88 - covers some 1,231 square degrees and contains several well-known stars. Cetus the Whale stands above the southwestern horizon these winter nights.
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