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Kiss the Sky Tonight -- Month of December 2020
A view showing how the Jupiter-Saturn conjunction will appear in a telescope pointed toward the western horizon at 7:00 PM EST, December 21, 2020. Jupiter and Saturn have been traveling across the sky together all year, but this month, get ready for them to really put on a show. Over the first three weeks of December, watch each evening as the two planets get closer in the sky than they've appeared in two decades. Look for them low in the southwest in the hour after sunset. And on December 21st, the two giant planets will appear just a tenth of a degree apart – that's about the thickness of a dime held at arm's length. This means the two planets and their moons will be visible in the same field of view through binoculars or a small telescope. In fact, Saturn will appear as close to Jupiter as some of Jupiter's moons. [Video Credits: NASA, JPL – Caltech, and the Office of Public Outreach – STScI, and WQAD-TV 8 ABC/MyNetworkTV affiliate] [Image Credit: Adapted by Patrick Hartigan from the open-source planetarium software Stellarium, used under GPL-2.0, and provided under CC BY 4.0 courtesy of Patrick Hartigan]
Kiss the Sky Tonight -- Month of December 2020
Welcome to the night sky report for December 2020 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. Step outside on a cold December night when the stars shine bright to find the Big Dipper, Cassiopeia, and Cepheus. They will help you locate a binary star system, a fan-shaped open star cluster, and a variable star. Also this month, catch the Geminids meteor shower. Then see Jupiter and Saturn come together in a conjunction to form a "double planet." Just after sunset on the evening of December 21st, Jupiter and Saturn will appear closer together in Earth’s night sky than they have since the year 1226 -- That’s 800 years ago during the Middle Ages. Is this like the Star of Bethlehem? No, not really -- I realize it is just two planets coming together in the sky (not a star), it’s pointing west instead of east, and it is a few days early for Christmas, but I couldn’t resist making the connection, so work with me here. (Interesting side fact, some have speculated that the true Star of Bethlehem could have been the conjunction of Jupiter and Venus near the bright star Regulus that occurred in the year 2 BC). The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard.
The long, frosty nights of December make for good sky gazing when the stars shine clear and bright. Face north to find the Big Dipper scraping the northern horizon.
The constellation of Cassiopeia the queen swings high on the other side of Polaris, the North Star. The constellation forms a clear “W” or “M” shape in the sky. Snuggled in the W pattern is Eta Cassiopeiae, a binary with a pale yellow Sun-sized star and a less massive orange companion.
Also tucked within the W pattern is the open star cluster M103. Binoculars or a small telescope show a fan-shaped group of about 170 stars, with a red giant star near the center.
To the east of Cassiopeia lies the fainter constellation of Cepheus, the king. His dim shape looks like the outline of a house. Along the base of the house lies Mu Cephei, a red giant also known as the Garnet Star for its deep red color. It’s also a variable star, changing in brightness over a period of hundreds to thousands of days.
To one side of the house’s base sits NGC 6946, a ragged spiral galaxy that appears as a ghostly patch of light in modest telescopes. NGC 6946 is known as the Fireworks Galaxy because of the frequency of supernovas occurring within it -- 10 within the past century. By comparison, the larger Milky Way averages just two per century. When viewed in the X-ray part of the spectrum, it reveals a galaxy filled with remnants of supernovas, whose energy contributes to heating the surrounding gas.
To the west of Cassiopeia we find the sprawling pattern of Perseus, the Greek hero and slayer of Medusa, whose head he carries. Among Perseus stars lies the open star cluster M34. Small telescopes or binoculars show a concentrated scatter of about 100 stars.
Face north to locate the Big Dipper and find galaxy M82. In binoculars and small telescopes, the galaxy appears as a thin rod of light. M82, seen edge-on, experienced a tremendous burst of star formation after an encounter with another galaxy. Multi-wavelength images show the effects of this starburst as it blows out dust and hot gas from its central regions.
Face east to find Orion the hunter with his shining belt rising over the early winter landscape. The glittering stars of winter rise with Orion and promise many fine stargazing nights to come.
December also brings one of the most reliable annual meteor showers, and one of the best in 2020 -- the Geminids. This shower is active from December 4th through the 17th, as Earth plows through the trail of dusty debris left behind in the orbit of asteroid 3200 Phaethon, which might actually be a burnt-out comet.
The Geminids produce a good number of meteors most years, but they're made even better this year as the shower's peak coincides with a nearly new moon, thus making for darker skies with no moonlight to interfere with the fainter meteors. The Geminids peak overnight on December 13th into the morning of the 14th, with some meteor activity visible in the days before and after. Viewing is good all night for the Northern Hemisphere, with activity peaking around 2:00 AM local time, and after midnight for viewers in the Southern Hemisphere.
For the best viewing, find a safe location away from bright city lights and look up. Meteors can appear in any part of the sky, though they'll appear to primarily radiate from near the constellation Gemini.
The Star of Bethlemem? (No, not really)
Jupiter and Saturn have been approaching one another in the night sky since the summer. From Dec. 16 to 25, the two will be separated by less than the diameter of a full moon.
Just after sunset on the evening of Dec. 21, Jupiter and Saturn will appear closer together in Earth’s night sky than they have been since the Middle Ages, offering people the world over a celestial treat to ring in the winter solstice in the northern hemisphere and the summer solstice in the southern hemisphere.
“Alignments between these two planets are rather rare, occurring once every 20 years or so, but this conjunction is exceptionally rare because of how close the planets will appear to one another,” says Rice University astronomer Patrick Hartigan. “You’d have to go all the way back to just before dawn on March 4, 1226, to see a closer alignment between these objects visible in the night sky.”
“On the evening of closest approach on Dec. 21 they will look like a double planet, separated by only 1/5th the diameter of the full moon,” said Hartigan, a professor of physics and astronomy. “For most telescope viewers, each planet and several of their largest moons will be visible in the same field of view that evening.
This event is called a "great conjunction." These occur every 20 years or so as the orbits of Earth, Jupiter, and Saturn periodically align making these two outer planets appear close together in our nighttime sky. Even so, this is the "greatest" great conjunction between Jupiter and Saturn for the next 60 years, with the two planets not appearing this close in the sky until 2080.
Though the best viewing conditions will be near the equator, the event will be observable anywhere on Earth, weather-permitting. Hartigan said the planetary duo will appear low in the western sky for about an hour after sunset each evening.
“The further north a viewer is, the less time they’ll have to catch a glimpse of the conjunction before the planets sink below the horizon,” he said. Fortunately, the planets will be bright enough to be viewed in twilight, which may be the best time for many viewers to observe the conjunction.
“By the time skies are fully dark in Houston, for example, the conjunction will be just 9 degrees above the horizon,” Hartigan said. “Viewing that would be manageable if the weather cooperates and you have an unobstructed view to the southwest.”
But an hour after sunset, people looking skyward in New York or London will find the planets even closer to the horizon, about 7.5 degrees and 5.3 degrees respectively. Viewers there, and in similar latitudes, would do well to catch a glimpse of the rare astronomical sight as soon after sunset as possible, he said.
Those who prefer to wait and see Jupiter and Saturn this close together and higher in the night sky will need to stick around until March 15, 2080, Hartigan said. After that, the pair won’t make such an appearance until sometime after the year 2400.
Dec. 21st is also the date of the December solstice, which is the winter solstice in the Northern Hemisphere and the summer solstice in the Southern Hemisphere. On the December solstice, the Sun reaches its southernmost position in the sky, no matter where on Earth you happen to be.
In the Northern hemisphere, the Sun travels its lowest, shortest path across the sky on that day. Thus, in the north, the winter solstice brings the shortest day of the year, in terms of hours of sunlight.
Now the Sun's changing height in the sky throughout the year is caused by Earth's tilt as it orbits our local star. The tilt causes the amount of sunlight each hemisphere receives to go up and down in the annual cycle of the seasons.
The night sky is always a celestial showcase. Explore its wonders from your own backyard.
The following Deep Sky Objects are found in constellations that peak during the month. Some can be viewed with a small telescope, but the majority will require a moderate to large telescope. The following is adapted from my personal viewing list: "The Guy Pirro 777 Best and Brightest Deep Sky Objects."
IC 342 Galaxy C5
IC 356 Galaxy P127
IC 361 Open Cluster P213
IC 3568 Planetary Nebula P128
NGC 1501 Planetary Nebula Herschel 400 H53-4
NGC 1502 Open Cluster Herschel 400 H47-7
NGC 1708 Open Cluster P129
NGC 1961 Galaxy Herschel 400 H747-3
NGC 2146 Galaxy P130
NGC 2336 Galaxy P70
NGC 2403 Galaxy C7, Herschel 400 H44-5
NGC 2408 Open Cluster P131
NGC 2655 Galaxy Herschel 400 H288-1
IC 10 Galaxy P77
IC 59 Diffuse Nebula P21 - Gamma Cassiopeiae Nebula (West)
IC 63 Diffuse Nebula P22 – Gamma Cassiopeiae Nebula (East)
IC 166 Open Cluster P217
IC 1795 Diffuse Nebula P122
IC 1805 Emission Nebula P2 Heart Nebula
IC 1848 Emission Nebula P3 Soul Nebula
IC 1871 Diffuse Nebula P136
NGC 103 Open Cluster P137
NGC 129 Open Cluster Herschel 400 H79-8
NGC 133 Open Cluster P138
NGC 136 Open Cluster Herschel 400 H35-6
NGC 146 Open Cluster P204
NGC 147 Galaxy C17 Satellite of Andromeda
NGC 185 Galaxy C18, Herschel 400 H707-2 Satellite of Andromeda
NGC 189 Open Cluster P5
NGC 225 Open Cluster Herschel 400 H78-8 Sailboat Cluster
NGC 278 Galaxy Herschel 400 H159-1
NGC 281 Emission Nebula P4 Pacman Nebula
NGC 381 Open Cluster Herschel 400 H64-8
NGC 436 Open Cluster Herschel 400 H45-7
NGC 457 Open Cluster C13, Herschel 400 H42-1 Owl Cluster
NGC 559 Open Cluster C8, Herschel 400 H48-7
NGC 581 Open Cluster M103
NGC 609 Open Cluster P219
NGC 637 Open Cluster Herschel 400 H49-7
NGC 654 Open Cluster Herschel 400 H46-7
NGC 659 Open Cluster Herschel 400 H65-8
NGC 663 Open Cluster C10, Herschel 400 H31-6
NGC 1027 Open Cluster Herschel 400 H66-8
NGC 7635 Diffuse Nebula C11 Bubble Nebula
NGC 7654 Open Cluster M52
NGC 7788 Open Cluster P139
NGC 7789 Open Cluster Herschel 400 H30-6 White Rose Cluster
NGC 7790 Open Cluster Herschel 400 H56-7
NGC 7795 Open Cluster P23
Caldwell 9 Diffuse Nebula C9 Cave Nebula
IC 1396 Open Cluster P6 Elephant Trunk Cluster
NGC 40 Planetary Nebula C2 Herschel 400 H58-4 Bow Tie Nebula
NGC 188 Open Cluster C1
NGC 2300 Galaxy P220
- NGC 2276 Galaxy - Paired with P220
NGC 6939 Open Cluster Herschel 400 H42-6
NGC 6946 Galaxy C12, Herschel 400 H76-4 Fireworks Galaxy
NGC 7023 Open Cluster C4 Iris Nebular Cluster
NGC 7142 Open Cluster Herschel 400 H66-7
NGC 7160 Open Cluster Herschel 400 H67-8
NGC 7226 Open Cluster P140
NGC 7235 Open Cluster P7
NGC 7261 Open Cluster P8
NGC 7380 Open Cluster Herschel 400 H77-8
NGC 7510 Open Cluster Herschel 400 H44-7
NGC 7762 Open Cluster P141
IC 1898 Galaxy P228
NGC 1084 Galaxy Herschel 400 H64-1
NGC 1232 Galaxy P28
NGC 1291 Galaxy P29
NGC 1300 Galaxy P81
NGC 1332 Galaxy P82
NGC 1407 Galaxy Herschel 400 H107-1
NGC 1535 Planetary Nebula Herschel 400 H26-4
NGC 1537 Galaxy P229
IC 348 Open Cluster P95
IC 2003 Planetary Nebula P237
NGC 650 Planetary Nebula M76 Little Dumbell Nebula
NGC 651 Planetary Nebula Herschel 400 H193-1 Part of M76
NGC 744 Open Cluster P96
NGC 869 Open Cluster C14a, Herschel 400 H33-6 Double Cluster (West)
NGC 884 Open Cluster C14b, Herschel 400 H34-6 Double Cluster (East)
NGC 957 Open Cluster P97
NGC 1023 Galaxy Herschel 400 H156-1
NGC 1039 Open Cluster M34 Spiral Cluster
NGC 1220 Open Cluster P238
NGC 1245 Open Cluster Herschel 400 H25-6
NGC 1275 Galaxy C24 Perseus A Seyfert Galaxy
NGC 1342 Open Cluster Herschel 400 H88-8
NGC 1444 Open Cluster Herschel 400 H80-8
NGC 1496 Open Cluster P174
NGC 1499 Diffuse Nebula P44 - California Nebula
NGC 1513 Open Cluster Herschel 400 H60-7
NGC 1528 Open Cluster Herschel 400 H61-7
NGC 1545 Open Cluster Herschel 400 H85-8
NGC 1582 Open Cluster P45
NGC 1605 Open Cluster P239
NGC 1624 Open Cluster P240
Messier 45 Open Cluster M45 Pleiades
Caldwell 41 Open Cluster C41 Hyades
IC 1995 Diffuse Nebula P64
NGC 1514 Planetary Nebula P120
NGC 1554 Diffuse Nebula P200 Von Struve’s Lost Nebula
NGC 1555 Diffuse Nebula P201 Hind’s Variable Nebula
NGC 1647 Open Cluster Herschel 400 H8-8
NGC 1750 Open Cluster Herschel 400 H43-8
NGC 1807 Open Cluster P65
NGC 1817 Open Cluster Herschel 400 H4-7
NGC 1952 Diffuse Nebula M1 Crab Nebula
Constellation: Ursa Major
Messier 40 Double Star M40 Winnecke 4
IC 2574 Galaxy P121 Coddington’s Dwarf Galaxy
NGC 2681 Galaxy Herschel 400 H242-1
NGC 2742 Galaxy Herschel 400 H249-1
NGC 2768 Galaxy Herschel 400 H250-1
NGC 2787 Galaxy Herschel 400 H216-1
NGC 2841 Galaxy Herschel 400 H205-1
NGC 2950 Galaxy Herschel 400 H68-4
NGC 2976 Galaxy Herschel 400 H285-1
NGC 2985 Galaxy Herschel 400 H78-1
- NGC 3027 Galaxy - Paired with H78-1
NGC 3031 Galaxy M81 – Bode’s Galaxy
NGC 3034 Galaxy M82, Herschel 400 H79-4 Cigar Galaxy
NGC 3077 Galaxy Herschel 400 H286-1
NGC 3079 Galaxy Herschel 400 H47-5
NGC 3184 Galaxy Herschel 400 H168-1
NGC 3198 Galaxy Herschel 400 H199-1
NGC 3310 Galaxy Herschel 400 H60-4
NGC 3556 Galaxy M108 Herschel 400 H46-5
NGC 3359 Galaxy P202
NGC 3587 Planetary Nebula M97 Owl Nebula
NGC 3610 Galaxy Herschel 400 H270-1
NGC 3613 Galaxy Herschel 400 H271-1 Paired with H244-1
NGC 3619 Galaxy Herschel 400 H244-1 Paired with H271-1
NGC 3631 Galaxy Herschel 400 H226-1
NGC 3665 Galaxy Herschel 400 H219-1
- NGC 3658 Galaxy - Paired with H219-1
NGC 3675 Galaxy Herschel 400 H194-1
NGC 3726 Galaxy Herschel 400 H730-2
NGC 3729 Galaxy Herschel 400 H222-1
- NGC 3718 Galaxy - Paired with H222-1
NGC 3813 Galaxy Herschel 400 H94-1
NGC 3877 Galaxy Herschel 400 H201-1
NGC 3893 Galaxy Herschel 400 H738-2
- NGC 3896 Galaxy - Paired with H738-2
NGC 3898 Galaxy Herschel 400 H228-1
NGC 3938 Galaxy Herschel 400 H203-1
NGC 3941 Galaxy Herschel 400 H173-1
NGC 3945 Galaxy Herschel 400 H251-1
NGC 3949 Galaxy Herschel 400 H202-1
NGC 3953 Galaxy Herschel 400 H45-5
NGC 3982 Galaxy Herschel 400 H62-4
NGC 3992 Galaxy M109, Herschel 400 H61-4
NGC 3998 Galaxy Herschel 400 H229-1
- NGC 3990 Galaxy - Paired with H229-1
NGC 4026 Galaxy Herschel 400 H223-1
NGC 4036 Galaxy Herschel 400 H253-1 Paired with H252-1
NGC 4041 Galaxy Herschel 400 H252-1 Paired with H253-1
NGC 4051 Galaxy Herschel 400 H56-4
NGC 4085 Galaxy Herschel 400 H224-1 Paired with H206-1
NGC 4088 Galaxy Herschel 400 H206-1 Paired with H224-1
NGC 4102 Galaxy Herschel 400 H225-1
NGC 4605 Galaxy P252
NGC 5322 Galaxy Herschel 400 H256-1
NGC 5457 Galaxy M101 Pinwheel Galaxy
NGC 5474 Galaxy Herschel 400 H214-1 Paired with M101
NGC 5473 Galaxy Herschel 400 H231-1
NGC 5631 Galaxy Herschel 400 H236-1
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