Telescope and Observing Tips for the 2020 Mars Opposition

If you’ve got a telescope, you’re likely excited for the Mars opposition occurring now—here are some quick tips to make sure you see everything as clearly as possible.

First, make sure you’ve got good “seeing” conditions—that is, that the skies are steady. If the stars are twinkling noticeably, it’s not a good night.

In October, try looking between midnight and 2 AM to get the sharpest, clearest image. Mars is visible low in the east after twilight, but if you aim your telescope at it then, you won’t get as sharp a view as you would if you looked later. That’s because looking near the horizon causes your telescope to peer through many more miles of our atmosphere than if you were looking straight up—in effect, a cause of poor seeing, even in a steady sky.

Give your scope adequate time to cool down to the outside temperature (at least 30 minutes—more with a big scope). You might not imagine that this could make a difference, but it does!

Avoid using magnification greater than your telescope can realistically provide—though it’s easy enough to create huge magnification by putting stronger eyepieces on your scope, the resulting image will get blurry after a certain point, worsening as the power is boosted further. As a guide, keep your magnification to around 25-30x per inch of aperture (so no more than 100-125x on a 4-inch scope, or 200-250x on an 8-inch, and so forth). These numbers assume your telescope is cooled down and you’ve got good seeing conditions (as discussed above); if not, you’ll have to set your power lower to get a reasonably sharp image.

And of course, ensure your telescope is collimated correctly (that is, your optics are well-aligned), and your eyepieces are clean.

Finally—relax! In spite of all the click-bait about “Mars Opposition on October 13th,” you’ll get similar views all the way into November—the exact date of opposition is just the “high water mark,” give or take, for this event, and you have much more time to enjoy the view than you think.

VIDEO: March 2020 Planetary Conjunction

Still Image from "Touring the Night Sky" Conjunction video.
Still image from a four-minute video showing you how to see the beautiful planetary alignments in late March. –Click image to go to the video on YouTube.

In spite of nasty viruses and all kinds of other misbegotten issues, the sky still performs its celestial dance–and we now have an opportunity to see the planets embrace as they perform a pre-dawn planetary conjunction–that is, two or more planets will line up closely from our point of view here on Earth. Mars and Jupiter will draw close on the morning of March 19, and even closer on Friday, the 20th. After that, they’ll continue to dazzle early risers–especially since Saturn is also nearby, and for part of the dance, at least, our Moon makes a cameo as a beuatiful crescent…

I have created a video covering the next several days’ planetary action, so you can see how these events will look–and which planet is which! It’s a little over four minutes, and I hope it inspires you to get out and look for yourself–here’s the YouTube link:

The Mercury Transit Explained

by Zachary Singer

Diagram of a transit of Mercury.
Diagram of a transit of Mercury.

(All illustrations © Zachary Singer.)

If you’ve heard about the November 11 Transit of Mercury (visible 6:39 AM – 11:04 AM, Mountain Standard Time, here in Denver), you may have a simple question: “What is it, and why is a transit a rare event?” The “what” is quick to answer; the “why” takes a bit longer, but isn’t hard to understand.

During a transit of Mercury, we see Mercury’s silhouette pass across the face of the Sun. It’s very much the same idea as a solar eclipse (when the Moon passes in front of the Sun), except that Mercury is so much farther away that it hardly covers the solar disk—all we see (through a telescope set up for safe solar viewing) is the planet’s “little black dot” move across the Sun over several hours.

If we could watch this event while looking down from a vantage high above our solar system, we’d see Mercury, the Earth, and the Sun arranged in a fairly straight line, with Mercury between the Earth and Sun (see Chart 1, below). Continue reading “The Mercury Transit Explained”

February Skies 2019

by Zachary Singer

Some of our favorite planetary targets, Venus and Jupiter, are up in the pre-dawn sky this month, and Mercury appears in the evening, as we’ll see in “The Solar System,” below. In “Stars and Deep Sky,” we’ll take a look at two notable open clusters in Auriga, M36 and M37.

The Solar System

Mercury starts off February still lost in the solar glare, but begins to reappear after the first week of the month. It’s still difficult on the 10th, but the party is just beginning—just a few days later, on Valentine’s Day, you’ll see Mercury glowing at magnitude -1.2; look for it low in the west, Continue reading “February Skies 2019”