Observer’s challenge: Moon and morning planets on February 8, 9 and 10
On February 8, 9 and 10, 2021 – if you look east shortly before sunup – you’ll see the old moon going, going, almost gone as it heads into the sunrise glare. New moon will come on February 11. If you’re up for a big challenge, you can use the moon early this week to try finding the three morning planets: Venus, Jupiter and Saturn. Fair warning. The planets are easiest to see from Earth’s Southern Hemisphere. They’re easier to see on our chart than in the real sky. No matter where you live worldwide, you’ll need a clear sky, an unobstructed eastern horizon and probably binoculars to tease these worlds out of the glow of morning twilight.
And, no matter where you live, the moon is your ticket to finding these worlds on February 8, 9 and 10. If your sky is clear, and you’re up early, try your luck!
Far and away, Venus is the most brilliant planet of these three planets. In fact, the queen planet Venus beams as third-brightest celestial body in all the heavens, after the sun and moon, respectively. Venus shines some six times brighter than the king planet Jupiter, and 65 times brighter than the ringed planet Saturn. That makes Jupiter nearly 11 times brighter than Saturn. Although the famous planet of the rings ranks as the faintest of the threesome, Saturn is nonetheless respectably bright, shining as brilliantly as a 1st-magnitude star, or one of the brightest stars in Earth’s sky.
On February 8 and 9, the illuminated side of the waning crescent moon points toward the lineup of planets. Look for Venus, the brightest planet, first. Then try for Jupiter below Venus, and Saturn above Venus. The trick is to know when Venus will be climbing above your horizon.
We give you Venus’ approximate rising time for the next several mornings at various latitudes, given an absolutely level horizon:
40 degrees north latitude: Venus rises about 24 minutes before the sun.
Equator (0 degrees latitude): Venus rises about 42 minutes before the sun.
35 degrees south latitude: Venus rises about 56 minutes before the sun.
The reason the Southern Hemisphere has the advantage is that – from there – the ecliptic, or pathway of the moon and planets, intersects the horizon at a relatively steep angle on February mornings. On the other hand, on February mornings in the Northern Hemisphere, the ecliptic hits the horizon at a relatively shallow angle. Although the planets’ elongations (angular separations) from the sun are the same in both the Northern and Southern Hemispheres, the shallow tilt of the ecliptic in the Northern Hemisphere keeps these morning planets deeply submerged in glare of morning twilight.
Look at the chart below for Valdivia, Chile (40 degrees south latitude). Valdivia, Chile, and Philadelphia, Pennsylvania, reside on nearly the same meridian of longitude (75 degrees west longitude). Yet, Philadelphia at 40 degrees north latitude, is about as far north of the equator as Valdivia is south of the equator. Hence, the steepness of the ecliptic in the Valdivia morning sky gives this southern outpost an advantage over Philadelphia. By the way, the featured chart at the top of this post approximates Philadelphia’s morning sky.
Day by day, Venus is now sinking closer to the sunrise. But Jupiter and Saturn are now climbing upward, away from the sunrise. So by the time that March 2021 comes rolling along, when Venus is lost from view, Jupiter and Saturn will be shining brightly in your morning sky.
And, even if you miss the planets on February 8, 9 and 10, the old waning crescent moon should be beautiful to behold on these mornings, with its dark side softly aglow in earthshine.
Bottom line: Try looking for Saturn, Jupiter, and Venus at dawn along with the waning crescent moon February 8, 9 and 10. The planets will be hard to see, but easier from the Southern Hemisphere.