Huestis: Dual Planetary Close Encounters

Sunday, May 29, 2016

David Huestis, GoLocalWorcester Astronomy Expert

Amateur astronomers have been observing the planet Jupiter for several months now. It’s much more convenient when you can catch a glimpse of this gas giant world during a reasonable evening hour. And we still have two more months where we can scrutinize Jupiter and his four Galilean moons before he sinks too low in the sky. But the heavens are going to oblige us with even more planetary pleasures to supplement our personal exploration of the solar system. Within four days of one another, Mars and Saturn will be at their closest distances to the Earth for 2016.

On May 30, Mars will be a mere 46,776,104 miles from us. Then on June 3, Saturn will be 837,996,600 miles from us. These dates are the absolute best times during 2016 to observe these two worlds, as they are closer and appear larger than usual through a telescope. To locate Mars and Saturn please look to the southeast sky around 10:00 p.m. on June 1 (see accompanying star map). If you have a good knowledge of constellation star patterns, you’ll notice Scorpius rising up at an angle above the horizon. The heart of the scorpion is the red giant star Antares, which means “rival of Mars”. Above Antares is the scorpion’s head and claws. This portion of the constellation comes between Mars and Saturn.

Pumpkin-orange colored Mars is to the upper right of Scorpius’ claws in the constellation Libra, while yellowish Saturn can be found to the lower left in Ophiuchus. Antares, Mars and Saturn will be the brightest objects in this region of the sky and will form a nice triangle. If you have a telescope you can begin observing the planets even before it gets completely dark on June 1, but you may want to wait until they rise higher above the horizon. You can visit Jupiter once again while waiting for that to happen. The local observatories may also have to wait until later in the evening or possibly an additional week or so due to obstructions of trees and houses.

To begin our examination of Mars please visit the following Skyscrapers website for a brief history of our second closest planetary neighbor. Suffice it to say that initial accounts of possible “canals” on Mars at the end of the 19th century captured our imagination and most assuredly hastened our exploration of this desolate world with spacecraft.

Now let’s review what an observer should expect to see through even a small telescope.

Mars’ close approach on May 30 will afford decent views through a telescope. While not the closest it can be, this close encounter is the closest one since 2005. So it is worth making every effort to observe one of our neighboring worlds to best advantage. For some Mars observers it might be a challenge to observe much detail considering how small the disk of the planet will appear. However, don’t let Mars’ small image size deter you from gazing at this planet. Medium-sized backyard telescopes should still coax some detail out of the small image. And of course the local observatories will be able to share even more Martian detail when steady seeing allows them to “crank up” the magnification.

Once you focus in on Mars with a telescope, the first detail you will notice will be the color. It’s not quite red, but not quite orange. Perhaps Crayola has a hue that best describes what we can see. How would you describe it? The second detail that will catch your eye will be the North Polar Cap (NPC). It’s definitely a bright white feature that can be seen because Mars’ north pole is currently tilted 12 degrees towards the Earth. (Since the tilt is so shallow, you may also catch a glimpse of the South Polar Cap, as it will still be winter in Mars’ southern hemisphere.) The cap will be small, but noticeable. Mars’ summer solstice in the northern hemisphere was on January 3, so a lot of polar melting will have occurred by the end of May. The NPC will continue to shrink as the Martian summer progresses. Meanwhile, the Earth/Mars distance will be increasing and the image size will be decreasing after our close encounter as the Earth “laps” Mars and pulls ahead in our respective orbits. The autumnal equinox (Fall) begins in Mars’ northern hemisphere on July 5. Dusky surface markings should be apparent under medium telescopic magnification. These features are the underlying rock exposed by the shifting sands during intense dust storms. Wait for steady seeing conditions to observe as much detail as possible.

A keen-eyed observer should be able to catch a few glimpses of a dark area like Syrtis Major or a bright one like Hellas Basin. You don’t have to know the names of the features you glimpse. Just simply enjoy the view of any surface feature you can observe. And though Mars is noted for producing dust storms that can globally enshroud the planet, it is unlikely that will happen during this time of close approach. Mars will be observable through the end of the year, and by December 31, it will be 152,488,340 miles from us. Our next close encounter will be on July 31, 2018, when Mars will almost be at its largest apparent size possible and only 35,785,537 miles away.

In conclusion, be patient when observing Mars. The planet’s disk will be small. Wait for steady seeing conditions. Don’t try observing Mars if the stars are twinkling. Take a knowledgeable look at this alien world that inspired generations of astronomers and science fiction writers alike to ponder the existence of Martian life-forms.

Drag out those telescopes and expose them to the light of the universe. One day your children or your grandchildren may set foot upon this exciting landscape.

Saturn: Lord of the Rings

As mentioned at the beginning of this article, Saturn will be at its closest distance to the Earth on June 3. This beautiful ringed-world is a spectacular sight even in a small telescope. The system of rings is easily seen and they are a most impressive sight. With the ring system tilted 26 degrees toward the Earth, we are viewing the north face of the ring plane. With the rings so “wide open,” this configuration allows much detail to be seen. Next year they will be at their maximum “openness” or tilt of about 27 degrees.

It is really amazing that Saturn’s rings are visible at all, considering the planet’s distance from the Earth and the fact that the ring plane is only about 328 feet thick (just larger than the length of a football field). The rings are composed of irregularly shaped dirty snowballs, ranging in size from grains of dust to the size of pebbles. There are also some “boulders” as large as several feet across. They all orbit Saturn along the planet’s equatorial plane. Look for gaps within the ring system.

Though Saturn is a gas giant a little smaller than Jupiter, it does not exhibit the prominent bands and zones in its cloud tops as its larger cousin does. Not much detail can be observed at all on Saturn’s disk. In fact, if it weren’t for Saturn’s ring system, this planet would be quite a boring destination for most amateur astronomers and the public alike.

What one can look for is the shadow of the rings upon Saturn’s cloud tops. The configuration of the rings provides a stunning 3-D effect of the Saturnian system, including eight of its brightest moons in a dark moonless sky with the telescopes available locally. We’ll be focusing on Saturn until between the first and second week of October, depending upon local horizon views.

So during the next few months, plan on treating yourself and your family and friends to wonderful views of Saturn and Mars through either your own telescope or one of the larger instruments at any of the local observatories. You won’t be disappointed.

Experienced sky interpreters will be on hand to provide incredible views of our local planetary family and distant stars, nebulae, galaxies and star clusters at each of the following facilities. Seagrave Memorial Observatory in North Scituate is open every clear Saturday night. Ladd Observatory in Providence is open every clear Tuesday night. The Margaret M. Jacoby Observatory at the CCRI Knight Campus in Warwick is open every clear Wednesday night. Frosty Drew Observatory in Charlestown is open every clear Friday night. Check the respective websites for open times.

Keep your eyes to the skies.