Planetary Parade!

Article November 23, 2024

People love a planet. It’s a truth I’ve had to face often in the Planetarium, as I try to drum up equal love for and fascination with things like asteroids, Kuiper Belt Objects, and moons (seriously, if I made a list of my favorite worlds in the solar system, something like 75% of it would be moons). But it’s hard to resist the draw of a planet.

That’s also true in the night sky. Folks love to see a planet in the wild, shining bright in among the stars. Which is why it’s so lucky that, at the moment, we’re getting a positive parade of planets easily visible in our night sky! Here’s what’s up and how to find them.

Mercury

Eh, honestly I say don’t bother. It’s up in the west for an hour after sunset, but Mercury isn’t easy to spot. It’s tiny, doesn’t have a reflective atmosphere to help us out, and it’s never far from the Sun. You’d need a fully clear western horizon (no buildings or trees) and it will probably take a telescope to spot it in the glow of the sunset. But if you’re quite determined to try, it will be the only thing even remotely possible to see between Venus and where the Sun set for that hour after the Sun itself is gone. I wish you luck.

Venus

Venus is pretty easy to spot. In fact, odds are you’ve already spotted it recently if you’ve been looking at the evening sky at all. It’s hard to miss. Just look westward (aka the direction the Sun sets) and it’s the brightest thing there. In fact, it’s so very bright that, at a casual glance, you might dismiss it as an airplane, because surely nothing in the sky would be so luminous.

Venus is the third brightest natural object in the sky, after the Sun and the Moon. I say “natural object” because the International Space Station, with its massive solar arrays only a couple hundred miles up, can outshine even Venus if the angles are right, but nobody would accuse the ISS of being a natural object. So when I say Venus is stupid bright, I’m only stating a fact.

It’s bright enough that you may be able to spot it in the sky before the Sun has actually finished setting. Its brightness is due to the face that it’s close to the Sun (only about 75 million miles from it), it’s close to us (it is the closest planet to us (never farther than 162 million miles from us, and as close as 24 million) and its entire surface is covered in bright, reflective clouds.

Relative positions of Venus and Saturn in the sky about one hour after sunset. The star with the marker on it is the bright star Fomalhaut. Credit: Stellarium

If you have access to binoculars or a telescope, check out Earth’s twin (the nickname comes from the fact that Venus is almost the same size as Earth. They actually look nothing alike). Because Venus is closer to the Sun than we are, it appears to go through phases from our point of view. So if you look at Venus through a telescope, you’ll see it as a crescent, or a gibbous, or a half Venus. The same is true of Mercury if you ever happen to be in a position to spot it.

Venus is up for two hours after sunset but that’s still pretty early in the evening these days, around 7pm. Check this one out on the early side.

Saturn

Next up in the planetary parade is Saturn. Saturn is well up in the sky once the Sun sets. You’ll want to look toward the south-southeast after sunset. Saturn doesn’t stick out as well as some of the other planets in our parade. After all, it’s nearly a billion miles away from us and the Sun, it just doesn’t reflect as much light our way. That said, we’re lucky that it’s currently in a part of the sky that doesn’t have many bright stars in it, making the planet easier to spot.

Looking towards the south-southwest (and more directly in the south by the time you’re getting to the time Venus is setting) you might, depending on your latitude and how clear your horizon is, see two bright objects. The lower one will be just a teensy bit brighter and slightly farther to the west (or to the right if you’re facing south). That’s not Saturn. That’s the bright star Fomalhaut.

Saturn will be higher than Fomalhaut, a wee bit dimmer, and a squib farther to the east. Depending on what the atmosphere above you is doing, it may also be a steadier light. Because planets are close enough to Earth for their light not to be a point source, like stars, their light passes through our atmosphere slightly differently than starlight, and they don’t twinkle as much as stars.

Saturn’s rings when they are more tilted towards the Earth during Saturnian summer/winter, and when they are more edge on towards Earth during Saturnian spring/fall. Credit: NASA/A. Bosh

Despite being nearly a billion miles from us, Saturn is bright enough to easily spot without the use of a telescope because it’s a huge reflective surface. It’s just really big (about ten Earths across) and, like Venus, its entire surface is light clouds which are excellent at reflecting light.

Depending on what season it is on Saturn it can get extra reflection from its bright ring system. At the moment though, it’s nearly fall/spring so the rings are almost edge on to us and not reflecting much light our way. If you have binoculars or a telescope, you’ll easily see the disk of the planet, but the rings will not be quite as impressive. You may still be able to spot some moons though, especially the big one, Titan, so it’s still worth checking out! Saturn’s not setting until around midnight, so you’ll have all evening to find it.

Jupiter

Jupiter rises in the east less than an hour before Venus sets in the west, just after 5:15pm, so if you happen to have fairly clear east and west horizons it may be possible to see Venus, Saturn, and Jupiter all up at once. It’s another easy one to spot, since it comes in just after Venus on the list of brightest natural objects in the night sky. Right now it’s actually smack between the horns of Taurus the bull and above the head of Orion.

That puts it pretty central between a bunch of bright stars, including the luminous Capella (part of Auriga the goatherder/charioteer. I know, Greco-Roman constellations are random), Aldebaran (the eye of Taurus, slightly reddish because this star is aging), and above the bright stars of Orion’s shoulders, Bellatrix and Betelgeuse. Despite being right in the midst of some of the brightest stars the Northern Hemisphere gets to see, it’ll still be the brightest thing there.

Like Saturn, Jupiter’s brightness comes from the fact that it’s a huge planet covered in clouds, but it’s even bigger than Saturn and way closer to us, about half the distance to Saturn. That means we get a much more intense reflection coming back our way.

A representation of what the Galilean moons of Jupiter might look like through a telescope. Remember, their positions change from night to night. Credit: Stellarium

Checking out Jupiter with binoculars or a telescope is always worth it if only for the moons. There are four that are easily seen with only small magnification. I’ve heard of people with telephoto camera lenses being able to see them. We call them the Galilean moons because Galileo was able to see them in the early 1600s with a fairly terrible telescope.

Their names are (starting with the closest to Jupiter) Io, Europa, Ganymede, and Callisto, and each of them is worthy of its own blog post. Because they all orbit Jupiter pretty quickly if you look at them from night to night (or even long enough later on the same night for Io or Europa) you can see their positions change around the planet. When Galileo first saw that it was proof that not everything orbited the Earth, which was a radical idea in the 1610s.

Jupiter doesn’t set until after sunrise, so once it’s up you have all night to view it.

Mars

The last in our planetary parade is Mars. It’s not rising until well after sunset, after 9pm. Its not nearly so bright as Venus or Jupiter, much closer to Saturn in brightness. But Mars is easier to spot than Saturn because it sticks out for its color.

Mars, of course, is famously nicknamed “The Red Planet”. It’s actually the Rusty Planet, but that doesn’t sound as good. A huge percentage of its surface is covered in rusted iron particles. Mars is rocky and doesn’t have a cloudy atmosphere, so it doesn’t reflect nearly as much light back at us as, say, Venus, but the light it does reflect is reddish.

When you spot it in the sky, that reddish color is apparent. I’m not talking “eye of Sauron” red or “blood of my enemies” red, but it will be redder than almost anything else in the sky. Its closest rival might be the red star Betelgeuse, but that star will be right above the distinct trio of Orion’s Belt, while Mars will be much farther to the east and won’t twinkle as much. It will actually be pretty directly between the heads of the Gemini twins and the front of Leo the lion.

You can check out Mars with binoculars or a telescope, but unless you’ve got a seriously fancy setup it’s basically going to look like a slightly bigger red dot. Sorry, it’s just not that big a planet. It’s also not setting until well after sunrise, so once it’s up you have all night to check it out.

Planets, Planets, Planets!

Another fun fact about these planets is that you can pretty much draw a line from one to the next to the next across the sky without much deviation. That’s because the planets of the solar system mostly orbit in the same plane, which we call the ecliptic. It corresponds to the Sun’s equator and runs through the constellations of the zodiac (which is another blog post of its own).

It also means that when the planets’ orbits have them positioned for easy early viewing we get to take in the vast diversity of worlds that can be found within the bounds of our solar system. Seriously, our solar system’s planets are so cool and so weird! And while admiring them, don’t forget to look down towards your feet. That’s where you’ll find the weirdest planet of them all.