Perfect time to spot planets, approaching comet
After being absent from the night and pre-dawn skies for the past several weeks, Mercury and Venus, our solar system's two innermost planets, finally return for a brief appearance in the western, evening sky this week.
Mercury (magnitude - 0.39, visible in Taurus — the Bull) appears around 8:30 p.m. (ADT), low above the westnorthwest horizon as the sun sets and dusk gives way to darkness. It will reach an altitude of around 11 degrees above the horizon before setting by about 10:20 p.m.
It will steadily climb higher in the post-sunset western sky during the following week, reaching its highest point in the evening sky as it achieves its greatest eastern elongation from the sun on May 17 — its best appearance of the year for northern viewers.
On May 12, Mercury reaches dichotomy, its half-lit phase (as seen through a telescope from Earth).
With a clear sky and an unobstructed view of the west-northwest horizon, you might glimpse bright Venus (magnitude -3.9, also seen in Taurus — the Bull) sitting low above the horizon (look for a bright "star-like" point of light in the post-sunset twilight), to the right and below Mercury, before it drops below the western horizon by about 9:20 p.m.
Mars (magnitude +1.6, visible in Gemini — the Twins) should be visible around the same time as Mercury and Venus (between 8:30 and 9 p.m.), about 29 degrees above the western horizon before it sets shortly after midnight.
If you're having difficulty finding these three planets in the post-sunset, western sky, use the waxing crescent moon as a guide. On the evening of May 12, a very slim crescent moon will sit low above the west-northwest horizon just after sunset (you'll need a clear sky and an unobstructed view of the horizon); the bright point of light immediately to its right will be Venus.
The next evening, a slightly larger crescent moon will be a bit higher in the evening sky, with Mercury to the lower right. The waxing moon is about equidistance between Mercury and Mars on the evening of May 14, and to the lower right of the Red Planet on the evening of May 15.
Jupiter and Saturn are late risers this coming week. Saturn (magnitude +0.8, look for it in Capricornus — the Sea Goat) tumbles out of its celestial bed around 2:30 a.m., visible 20 degrees above the southeast horizon, and then fades with the approaching dawn by about 5 a.m. Jupiter (magnitude -2.3, look for it in Aquarius — the Water Bearer) makes a bright but brief appearance in the pre-dawn, southeast sky, rising around 3:10 a.m., reaching an altitude of 20 degrees above the horizon before it, too, fades with the glow of the approaching dawn by about 5:20 a.m.
COMET COMING
Keep a sky-eye on Comet C/2020 T2 (Palomar) over the next few weeks. Currently at magnitude 10.5, in the constellation of Canes Venatici — the Hunting Dogs (beneath the tail of Ursa Major — the Great Bear), Comet T2 is visible all night for viewers in the northern hemisphere.
Under a clear sky away from city lights, it will become visible by about 9:50 p.m. (ADT), 60 degrees above the eastern horizon. It reaches its highest elevation in the night sky shortly after midnight, 75 degrees above the southern horizon, before fading from view around 4:30 a.m., 38 degrees above the western horizon.
Although not currently expected to achieve naked-eye visibility, Comet T2 should brighten to be visible in binoculars in the coming weeks.
Until next week, clear skies.
EVENTS
• May 11 - New moon; moon at apogee (farthest from Earth)
• May 12 - Mercury at dichotomy (half-lit phase)