THE SOUTHWORTH PLANETARIUM 207-780-4249 www.usm.maine.edu/planet <http://www.google.com/url?q=http%3A%2F%2Fwww.usm.maine.edu%2Fplanet&sa=D&sntz=1&usg=AFQjCNHulkHuLP13bOG2PkNrPazsGWFs2A> 70 Falmouth Street Portland, Maine 04103 43.6667° N 70.2667° W Altitude: 10 feet below sea level Founded January 1970 Julian Date: 2459219.18 2020-2021: LXV THE DAILY ASTRONOMER Tuesday, January 5, 2021 January 2021 Night Sky Calendar Part II *SUNDAY, JANUARY 10: MERCURY, JUPITER AND SATURN WITHIN A CIRCLE 2.4 DEGREES IN DIAMETER (GOLD EVENT!!!)* Low in the western evening sky tonight one will see a lovely planetary trio: Mercury, Jupiter and Saturn. Fortunately, these planets are all quite conspicuously bright. Unfortunately, they are all close to the Sun and so will begin the night low above the western horizon. One can use their relative brightnesses and positions to identify these worlds. Jupiter (magnitude -1.8) will be the brightest of the three. Mercury (magnitude -0.8) will be brighter than Saturn (magnitude 0.6). Mercury and Saturn appear close together and will both set at 5:17 p.m. Jupiter, slightly away from the others, will set 11 minutes later. This proximity is illusory. Though they might appear near one another, immense amounts of space separate these planets. Mercury will be 118 million miles from Earth tonight, while 561 million miles separate Earth and Jupiter. Meanwhile, Saturn's distance from us will slightly exceed one billion miles this evening. *MONDAY, JANUARY 11: WANING CRESCENT MOON NEAR VENUS (SILVER EVENT!!)* See the waning crescent moon (4% illuminated) in the eastern pre-dawn sky. Even those sky watchers who are not inclined to rise so early should wander out to glimpse these two gorgeous celestial sights together. The moon and Venus are the night sky's two brightest objects. Though always beguilingly beautiful, they are even more captivating when seen together. *WEDNESDAY, JANUARY 13: NEW MOON * Beginning of lunation cycle 1213. *THURSDAY, JANUARY 14: MOON NEAR MERCURY* One can find the thin sliver waxing crescent moon (3% illuminated) in the western evening sky tonight. Both bodies will set in the west by 6:00 p.m. *WEDNESDAY, JANUARY 20: FIRST QUARTER MOON* *THURSDAY, JANUARY 21: MOON NEAR MARS (BRONZE EVENT!)* The waxing gibbous moon (58% illuminated) is close to Mars this evening. They both begin the night high in the eastern sky. The moon sets about half an hour after midnight. Mars sets just before 1 a.m. *THURSDAY, JANUARY 21: MOON AT APOGEE* Yesterday we included the "Moon at perigee" event (January 9th). Perigee is the point on the moon's orbit that brings it closest to Earth. The moon reaches the apogee point , that of greatest distance, today. The difference between the perigee and apogee distance amounts to about 40,000 kilometers. (This month's perigee distance is 367,387 km; the apogee distance equals 404,360 km) Although 40,000 kilometers seems substantial to us, as it is nearly equal to Earth's equatorial circumference, as we can tell from the graphic below, the actual difference is slight in terms of the moon's orbit. The dashed circle represents the moon's mean orbit and the solid curve describes the moon's actual orbital path. One can see that the moon's orbit deviates only slightly from circularity. [image: perigee-apogee-brian-koberlein-e1443384711895.png] *SUNDAY, JANUARY 24: MERCURY AT GREATEST EASTERN ELONGATION* Superior planets are farthest from the Sun in our sky when they are at opposition. Inferior planets -those closer to the Sun than Earth- attain their greatest distance from the Sun in our sky when they are at greatest elongation. When an inferior planet is at greatest western elongation, it is visible in the eastern pre-dawn sky. When an inferior planet is at greatest eastern elongation, it is visible in the western evening sky. Mercury is at greatest eastern elongation day and will be 19 degrees away from the Sun. [image: mercury-greatest-elongation.jpg] This is the best time of the month to find Mercury due to its apparent distance from the Sun. (See PLANET WATCH) *SUNDAY, JANUARY 24: SATURN AT SUPERIOR SOLAR CONJUNCTION* If you're outside looking for Mercury, don't bother trying to find Saturn. Saturn will be at superior solar conjunction, or at the far side of the Sun relative to Earth, today. Saturn will return to the morning sky later this winter. *THURSDAY, JANUARY 28: FULL MOON* The January full moon is known as the "Wolf Moon," the "Old Moon," as well as the "Moon After Yule" and the "Winter Moon." While three of the names are sensible, the origin of "Old Moon" is unclear, as it is the first full moon of the new year. *FRIDAY, JANUARY 29: JUPITER IN SUPERIOR SOLAR CONJUNCTION* Today Jupiter moves to the far side of the Sun relative to Earth. Like Saturn, Jupiter will not be visible until later this winter when it will re-emerge in the eastern pre-dawn sky. PLANET WATCH *MERCURY (PICK PLANET!)* *Host constellations: *Beginning of month: Sagittarius; Middle to end of month: Capricornus What?! Mercury is never the pick planet....well, almost never. The elusive first world never veers far from the Sun in our sky and so is often difficult to find. However, January 2021 is the month for mid-latitude Mercury watchers. At month's beginning, World One rises higher each night in the western evening sky. On January 10th,Mercury joins Jupiter and Saturn to form a beautiful planetary trio. On January 23rd, Mercury will be at greatest eastern elongation. One will be able to see Mercury for an hour and half after sunset around this time. VERDICT: Of the five visible planets, Mercury is generally the most difficult to observe. In fact. even some dedicated skywatchers have admitted that they have rarely ever seen this winged messenger planet. If you want to see it, this month offers ample opportunity to do so. Just venture outside half an hour after sunset and look for it low in the western evening sky. *VENUS* *Host constellations: *Beginning of month: Ophiuchus; middle to the end of the month: Sagittarius One of nature's firmest rules: unless it isn't visible, Venus will always outshine every other planet and all the night sky stars. This month, Venus draws closer to the Sun. Visible in the pre-dawn eastern sky, Venus will rise progressively later each morning. On January 1st, Venus rises at 5:48 a.m. On January 31st, the second planet appears at 6:26 a.m. VERDICT: As Venus will be moving into superior solar conjunction on March 26, 2021, we won't be able to see Venus as the "morning star" for much longer. Seek it out while you can if you happen to rise before the Sun. *MARS* *Host constellations: * Beginning of the month: Pisces; middle to the end of the month: Aries Though not nearly as brillant t now as it was during its opposition, Mars remains one of the night sky's brightest sights. The red planet begins the night high in the eastern sky. In early January it will set around just after 1 a.m. At month's end, it will set about twenty minutes before one. VERDICT: Planet watchers who don't want to rise before dawn or venture outside just after dusk should look for Mars. It will be perfectly positioned throughout the early evening. *JUPITER* *Host constellation*: Capricornus Jupiter certainly garnered an immense amount of media coverage last month as it drew to within a degree of Saturn. However, Jupiter is now preparing to exit stage west. Though still visible in early January, Jupiter will be out of sight by the third week of the month. VERDICT: Seek out Jupiter during the first two weeks of January. On January 28th, the mammoth planet will move to the far side of the Sun (superior conjunction) and won't be visible. Be sure to find Jupiter on the 10th when it will be part of a planetary trio along with Mercury and Saturn *SATURN* *Host constellation: *Capricornus Saturn and Jupiter truly made spectacles a of themselves last month. Now they are both about to set with the Sun. Saturn will leave first. The ringed world exits by the 15th, less than a week after it joins the planetary trio with Mercury and Jupiter. Saturn moves into superior solar conjunction on January 23rd. VERDICT: Find Saturn low in the western sky during the first two weeks of January. Of course, the earlier in the month you seek it, the easier it will be to find. To subscribe or unsubscribe from the Daily Astronomer: https://lists.maine.edu/cgi-bin/wa?SUBED1=DAILY-ASTRONOMER&A= <https://lists.maine.edu/cgi-bin/wa?SUBED1=DAILY-ASTRONOMER&A=1>