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For those of you who like to listen to your stories, click below to hear Susan Trishel Monsøn reading Chris Vaughan’s summary of the planets for February.
Mercury will be visible low in the western post-sunset sky during the first few days of February, and then it will disappear from view until after inferior solar conjunction on February 8. After Mercury enters the eastern pre-dawn sky around mid-February, the shallow morning ecliptic will keep the planet low in a twilit sky and difficult to see except for observers at southerly latitudes, where Mercury will shine in a darker sky. Mid-northern latitude observers can look for the planet between about 6:15 and 6:30 a.m. local time during the rest of February. Viewed in a telescope during the month, Mercury will show a waxing, half-illuminated phase and an apparent disk diameter that shrinks to 8 arc-seconds by month-end. On the mornings surrounding February 23, the orbital motion of Mercury will carry it above and between Jupiter and Saturn, but you will need a cloudless and unobstructed east-southeastern horizon to see those planets.
During February, magnitude -3.9 Venus will become progressively less visible over the southeastern horizon because its elongation from the Sun will decrease from 13 degrees to just 6.5 degrees. On February 6 and 11, Venus will pass half a degree south of Saturn and Jupiter respectively. On February 10, observers at southerly latitudes can look for the slim crescent of the old moon sitting a palm’s width to the right of Venus.
Mars will continue to be conveniently positioned for observing high in the western sky on February evenings, but its apparent disk size will shrink from 7.8 to 6.3 arc-seconds and its visual magnitude will decrease from 0.46 to 0.93 — the latter comparable to nearby Aldebaran. On February 23, Mars’ eastward prograde motion along the ecliptic will carry it from Aries into Taurus, and the planet will end the month just a few degrees to the southwest of the Pleiades. On February 18, the waxing, half-illuminated Moon will be positioned several finger widths below (or 3.7 degrees to the celestial south) of Mars.
Following its conjunction with the Sun at the end of January, magnitude -1.9 Jupiter will enter the eastern pre-dawn sky in February, but the shallow morning ecliptic will keep the planet embedded in morning twilight all month long. Jupiter will be accompanied by fainter Saturn, sitting 8 degrees to its west, and by Venus, which will pass half a degree to the south of Jupiter on February 11. On the mornings surrounding February 23, the orbital motion of Mercury will carry it above and between Jupiter and Saturn.
Having been in conjunction with the Sun on January 24, magnitude 0.65 Saturn will enter the eastern pre-dawn sky in February. The shallow morning ecliptic will keep Saturn low all month long, but the ringed planet will begin to shine among the stars of western Capricornus during the second half of the month. All month long, brighter Jupiter will be positioned to Saturn’s east and will slowly be increasing its distance from Saturn. Bright Venus will pass half a degree south of Saturn on February 6, but the ringed planet will be too faint to see with unaided eyes. On the mornings surrounding February 23, the orbital motion of Mercury will place it above and between Saturn and Jupiter.
During February magnitude 5.75 Uranus will be slowly traveling eastward through the stars of southwestern Aries. It will be descending the western sky after dusk, making the blue-green planet an early evening target only. Telescope views of the planet will show a tiny 3.7 arc-seconds wide disk. On February 17, the waxing crescent Moon will shine 4 degrees to the southeast of Uranus. Note Uranus’ position about midway between the medium-bright stars Menkar (Alpha Ceti) and Sheratan (Beta Arietis) and search for it with binoculars, or even your unaided eyes, on a subsequent moonless night.
Distant blue Neptune will be moving slowly eastward through the stars of eastern Aquarius during February, but the magnitude 8 planet will be too faint and too low in the western sky for observing after the opening days of February.
Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through AstroGeo.ca to tour the universe together.