An Invitation To Observe Saturn Tonight

The waxing moon, now in gibbous phase, appears several degrees to the right or west of the planet Saturn this evening. Source: Stellarium
The waxing moon, now in gibbous phase, appears several degrees to the right or west of the planet Saturn this evening in the dim constellation Libra next door to Scorpius the Scorpion. Source: Stellarium

The waxing moon coasts to Saturn’s side tonight. With Jupiter and Venus now so low in the west after sunset, Saturn is quickly becoming our only evening planet. While more planets means more fun, I don’t feel deprived. We’ve had a great year so far with Mercury, Venus and Jupiter putting in bright and lasting appearances. No planet truly goes away. Venus will soon leap into the morning sky. Jupiter will do the same, but take more time because it’s much farther from Earth.

If you’ve been wondering where Mars is, it’s right over your head! The Red Planet’s just a fist width to the right of the Sun and completely lost in the glare of daylight. Watch for it to brighten up in the late summer sky before dawn. On November 3, the planet has a superb conjunction with Venus.

Earlier this week under the calmest skies in a month, Saturn shone sharp and serene through the eyepiece of my telescope. I may have looked at the ringed planet somewhere around 1,000 times in my life, but can’t help coming back for more. It’s the only planet with rings we can see. Jupiter’s got ’em, so do Uranus and Neptune, and there are probably millions of hula-hooped planets across the galaxy. But only Saturn gives its secret beauty away with ease; even a 30-40x spotting scope will show its unique character. To my knowledge, it’s the only natural object of its kind — a sphere surrounded by a ring.

Three sketches of Saturn by Galileo. As his telescopes improved, the nature of Saturn became clearer.
Three sketches of Saturn by Galileo. As his telescopes improved, the nature of Saturn’s ring became clearer.

Is it any wonder Galileo, the first to see this unique object, couldn’t figure out what he was looking at. Not only were his optics sketchy, but he had no reference with which to compare this strange sight. On July 15, 1610 the Italian astronomer pointed his 30x telescope at the planet and made this observation:

“The star of Saturn is not a single star, but is a composite of three, which almost touch each other, never change or move relative to each other, and are arranged in a row along the zodiac, the middle one being three times larger than the two lateral ones.” During another later observation, two of the three “bodies” completely disappeared, which must have been a real head-scratcher for the poor guy. Galileo saw an edgewise presentation of the rings; despite their vast extent, they’re so thin, they disappear in many telescopes for a time when edge-on to to Earth.

Painting of Galileo Galilei showing the Doge of Venice how to use the telescope.
Painting of Galileo Galilei showing the Doge of Venice how to use the telescope.

He looked again with an improved telescope in six years later in 1616. Expecting to see three bodies as during his first observation, Galileo encountered a different appearance:

“… whose two companions are no longer two small, perfectly round globes as they were before, but are at present much larger bodies, and no longer round, as seen in the adjoined figure, that is, two half ellipses with two dark little triangles in the middle of the figures, and contiguous to the middle globe of Saturn, which is seen, as always, perfectly round.”

Galileo’s “handles” or “ears” as he called them were finally explained by astronomer Giovanni Cassini in 1855. He wrote that Saturn “is surrounded by a thin, flat, ring, nowhere touching, inclined to the ecliptic.” And now you can go out and wonder at the sight yourself with even the most inexpensive optics.

Saturn tonight around 10 p.m. CDT. Titan, the brightest moon, is easy to see in any telescope. The others shown here are fainter - around magnitude +10-10.7. If air turbulence is low, see if you can see the division in Saturn's rings called Cassini's Division. It divides the outer A-ring from the wider, brighter B-ring. North is up, east to the left. Source: Stellarium
Saturn tonight around 10 p.m. CDT. Titan, the brightest moon, is easy to see in any telescope. The others shown here are fainter – around magnitude +10-10.7. If air turbulence is low, see if you can see the division in Saturn’s rings called Cassini’s Division. It divides the outer A-ring from the wider, brighter B-ring. North is up, east to the left. Source: Stellarium

We’re smack in the middle of the best time to observe the planet, since it’s highest in the south at nightfall. With the moon parked so close, anyone can find it. Saturn shines a little brighter than Antares in Scorpius, located 620 light years away. Saturn’s 932 million miles (1.5 billion km) from Earth today which sounds far until you realize that’s three times closer than Pluto. Viewed through a small telescope, you’ll see the ring system and at least one of its moons, Titan. The other three are visible in a 6-inch or larger telescope. If the air is calm, try to see the narrow, dark gap separating the A and B rings called Cassini’s Division. Internal to the B-ring is yet another ring – a dusky, translucent one – called the C-ring.

Enjoy a look at Saturn the next clear night and consider how fortunate we are to live in a time when anyone can afford a telescope that will show such wonder with ease.