See January’s “Planet Parade,” plus Comet ATLAS Now Visible in Daylight – Sky & Telescope

I like easy. Mining the deep-sky or spending a half-hour teasing out Martian surface features have their rewards, but it’s been a blast to scan the evening sky this month and enjoy the planets with just my eyes.

Venus and Saturn are paired in the west and will be in conjunction this coming weekend. Turn around and face east, and Jupiter and Mars eagerly greet your gaze. Add in the glitter of the Winter Hexagon and its captive, Betelgeuse, and you’ve got seven shimmering stars and four bright planets bent on getting your attention the next clear night.

Maybe you’ve heard about a rare planetary alignment happening on January 25th. Not to steal the joy, but the four brightest planets have occupied the evening sky simultaneously since early December and will continue to do so through late February — so no need to limit your nights out!

Moreover, it’s not rare to have multiple planets in the sky at the same time, though it’s a little uncommon for the four brightest to be so well-placed and accessible. The planets can’t help but line up, because they all orbit within a few degrees of the solar system plane, better known as the ecliptic. Since Earth occupies the same plane, when we gaze into space, the planets look like bright beads strung across an invisible wire that stretches from horizon to horizon and continues below it to include the morning-sky planets.

In fact, there are actually six of our planetary siblings visible right now at nightfall, although two of them — Uranus and Neptune — require binoculars or a small telescope to spot. To find the ice giants, you can make finder charts at in-the-sky.org: Click the Charts heading. In the drop-down menu select Objects-finder charts. Type the planet’s name in the Object box, set the date and click Update.

What’s been grabbing attention these evenings is how many planets are visible simultaneously and how tightly bunched they are. Right now, Mercury is in the morning sky and unfortunately hidden in the Sun’s glare. It’s off the list. But the remaining 6 accessible planets span 136° of sky at the moment.

That’s not bad but nowhere close to a record. We saw a tighter gathering of all of the planets back in June and July of 2022, when the full crew plus the Moon spanned 91° of sky before dawn. The cherry on top was that the brightest planets were lined up in order of distance, from Venus (farthest east) to Saturn (farthest west). No such symmetry plays out in the current lineup.

Things actually become more interesting in late February. Starting around February 23rd, Mercury begins a bright run in the evening sky. While Saturn will be nearly lost in the glow of dusk, dedicated observers should be able to see both planets during early-to-mid twilight under good conditions with binoculars or a small telescope. They’ll be in conjunction, less than 2° apart, on February 25th. As the sky darkens, Neptune, followed by Venus, Uranus, Jupiter, and Mars will appear to make a total of seven planets strung across about 119° of sky.

In case you’re wondering if it’s possible for all of the planets to align, so they’re stacked on top of one another, practically speaking the answer is no. Each planet orbits the Sun with a different inclination, ranging from 0.8° for Uranus to 7° for Mercury. Earth is a special case: Its inclination is 0° because it defines the plane of the solar system. This means the planets, like the Moon, slowly weave above and below the ecliptic plane, precluding a bullseye alignment.

For fun, we can instead calculate how often the eight major planets cluster within 1° of each other. Sky & Telescope Contributing Editor Tony Flanders did the math back in July 2006, and arrived at 13.4 trillion years. But by then, the future Sun will have engulfed Mercury and Venus and messed with the orbits of the surviving planets, preventing such a close alignment from happening.

Check out the sights: Planet by Planet

The planet procession is a great opportunity, especially for beginning observers, to find each planet and trace how it moves against the background stars as it orbits the Sun. Like the Moon and Sun, planets travel eastward along the ecliptic . . . usually. (In a moment I’ll describe an exception.) Careful observation will also reveal the seasonal drift of the planets and constellations, which shuttle westward over the weeks and months as Earth revolves around the Sun. Binoculars or telescopes can also reveal additional details.

In a telescope, Venus shows phases just like the Moon. On January 7th, it looked like a perfect half-moon in my telescope. I also couldn’t help notice how far to the south the planet shines this month. The reason is easy to understand. Not only is Venus near its greatest elongation from the Sun, but the Sun sets far to the south of west in Sagittarius. That big separation also makes it easy to spot the planet well before sunset. Once you become familiar with finding Venus, try going out earlier and looking for it. If you’ve never seen it in the daytime before you’ll be pleasantly surprised.

I discussed viewing Mars with both the naked eye and telescope in this recent post, but I want to be sure to remind you again that the full Moon will occult the planet on Monday night, January 13th for North America. You’ll find disappearance and reappearance times on the International Occultation Timing Association’s website.

Earth is lapping Mars as the planet approaches opposition on January 16th. From our speedier perspective, Mars is now moving from night to night “in reverse,” or retrograde motion, headed west out of Cancer and into Gemini. This Earth-induced movement will be on dramatic display in the coming week as Mars aligns beneath Gemini’s brightest stars, Pollux and Castor. The trio will make a straight line on January 16th and 17th.

Saturn looks dull compared to brazen Venus, but the view through a telescope is anything but. Watch as its rings narrow this month from the current 3.6° to 2.7° on Jan. 31st.

Jupiter is always a joy. The brilliant beacon of cream-colored light shines just 5° from Aldebaran in Taurus. Like Mars, it’s also in retrograde motion. A pair of 7x or 10x binoculars will reveal from one to all four of its brightest moons. To know which is which consult Sky & Telescope’s Jupiter’s Moons tool.

Update: Amateurs spot comet ATLAS in daylight

In other news, it looks like Comet ATLAS (C/2024 G3) is going to plow through perihelion intact. Observers reported it at around magnitude –3 on January 12th and visible in daylight through suitably baffled telescopes. Others hid the Sun below a roofline and spotted the comet in binoculars.

Comet ATLAS is big and bright in the Solar & Heliospheric Observatory’s (SOHO) LASCO C2 coronagraph images. Follow it online the next couple days as it crosses the field of view. So exciting!