The sky this week from December 17 to 31

Sunday 26 December
Mars passes 5 ° due north of Antares at 1:00 p.m. EST. Although they are obscured by daylight by this time, you can catch them early this morning, about 10 ° above the horizon 30 minutes before sunrise.

Meanwhile, evening watchers should focus on Jupiter after sunset, where the Galilean moons put on a show. By nightfall, you will only see three of the four moons: Callisto closest to the eastern limb of the planet, with Io then Ganymede further east. But keep an eye out for things for the next few hours: At 8:24 p.m. EST, Europe is about to emerge from Jupiter’s long, dark shadow. It will reappear about 26 “from the eastern limbus – further away of the limb that Callisto is now seated. This is because the planet’s shadow stretches far behind it, as Callisto approaches ahead. It will begin to transit the disc at 8:53 p.m. EST and should be visible as a bright spot against the cloud tops next to the large red spot, also rotating on the visible side of the planet at the same time. time. Jupiter will set around 9 p.m. local time, with Callisto still crossing its 36-inch-wide disc.

The last quarter moon is also occurring this evening, with our satellite reaching this phase at 9:24 p.m. EST.

Sunrise: 7:21
Sunset: 4:41 p.m.
Moon setting: 12:01
Moon phase: Gibbous decreasing (54%)

Monday, December 27
The constellation Lynx rises above the horizon as the sun sets this evening. Wait a few hours then take advantage of the moonless sky before midnight to spot NGC 2419, the intergalactic traveler.

This globular cluster has received a strange name due to its distance, some 300,000 light years away. This is nearly double the distance of the Milky Way’s largest satellite galaxy, the Large Magellanic Cloud. Initially, astronomers weren’t sure this cluster was orbiting the Milky Way, but have since found out that it is. Nonetheless, this great distance is why NGC 2419 seems so small (around magnitude 9, so go for a 4 inch or larger telescope), as it is physically quite large and inherently bright.

To find this compact cluster, it is actually easier to use a landmark in nearby Gemini: the bright star Castor is located 7 ° due south of the Intergalactic Wanderer. While you’re in the area, perhaps take some time to enjoy Castor himself, whose luminous A and B components (2nd and 3rd magnitude, respectively) are only a few arc seconds apart. Castor C is 1.2 ‘to the south – see if you can spot this 9th magnitude star as well. Each of the those three stars is a binary, bringing the total number of stars in this system to six.

Sunrise: 7:21
Sunset: 4:42 p.m.
Moonrise: 12:08 am
Moon setting: 12:25
Moon phase: Descending descending (43%)

Tuesday 28 December
Mercury has finally emerged from the glare of the Sun and is visible in the evening. Tonight, the smallest planet in the solar system passes 4 ° south of Venus at 8 p.m. EST. Both planets are below the horizon then, so catch them just after sunset, when they are 4.2 ° apart and about 7 ° elevation in the southwest. 30 minutes after the Sun disappears.

Venus is much brighter – magnitude –4.5 – while tiny Mercury still shines at a decent magnitude –0.8. It should be easy to grab both with binoculars or zoom in on one at a time with a telescope. Mercury’s face stretches only 6 “and is 84% ​​illuminated; Venus is much wider at 59” but only 4% illuminated.

Over the next few days, Mercury will continue to move higher in the sky each evening, becoming easier to catch longer after sunset.

Sunrise: 7:21
Sunset: 4:42 p.m.
Moonrise: 01h17
Moon setting: 12h51
Moon phase: Descending descending (32%)

wednesday 29 december
The open cluster Collinder 89 rises with Gemini the Twins after sunset. According to Astronomy Columnist Stephen James O’Meara, this cluster could also be called the Peek-a-Boo cluster because so many people see it without realizing it!

The twenty stars of Collinder 89 shine with a total apparent magnitude of 5.7. They are located in the 0.7 ° wide space between the two brightest stars 9 and 12 Geminorum, which are magnitude 6 and 7 respectively. If you need a brighter panel, start with Mu ( μ) Gem, which shines at magnitude 2.9, and look 1.5 ° northwest. The best way to see this target is with binoculars or a low power telescope eyepiece.

Take your time and enjoy that loose elliptical cluster – then watch (without change your field of view) closer to 12 Gem to note that it is veiled in a 30 ‘wide reflection nebula: IC 444. If you cannot see it, note the field and increase your aperture or power to try again. Visual observers will likely only see the brightest 10 feet of this nebula, but astroimaggers will be able to capture the full extent of its glow.

Sunrise: 7:22
Sunset: 4:43 p.m.
Moonrise: 02:28
Moon setting: 13:21
Moon phase: Descending descending (22%)

Thursday, December 30
Andromeda the Princess is high in the northern sky after sunset tonight – the perfect opportunity to hunt down the winter-themed blue snowball. Also cataloged as NGC 7662, this object is a planetary nebula created by a dying Sun-like star. As the star ages, it is blown from its outer layers into a spherical shell, subsequently igniting this tenuous gas.

The blue snowball is about 2,200 light years away. At this distance, it stretches about 30 “across the sky and shines at magnitude 8.3 – easy for binoculars or a small telescope. You will find it about 4.5 ° east of magnitude 3. , 6 Omicron (ο) Andromeda, located near this long western border constellation Take a look for yourself and enjoy the bright blue color of this namesake nebula.

Sunrise: 7:22
Sunset: 4:44 p.m.
Moonrise: 03:44
Moon setting: 13:56
Moon phase: Descending descending (13%)

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