Closest Approach: October 6
Opposition: October 13
Some sizes for the month after opposition: How fast does Mars shrink after an opposition?
October 16 22.3" November 6 19.3" October 23 21.6" November 13 18.0" October 30 20.6" November 20 16.7"
The view favors Mars' southern hemisphere, which will be experiencing summer around the time of opposition, so the south polar cap isn't very visible.
Here are the slides for a talk I gave on Observing Mars at Opposition on October 16, 2020 for the PEEC Planetarium in Los Alamos, NM (press spacebar or → to advance to the next slide).
If you prefer, you can skip the FAQ and jump directly to the links.
There is a message floating around the internet about an amazingly close Mars opposition where "Mars will be as big as the moon!" That message is a hoax, and it's full of misinformation. It describes an opposition that happened in 2003. It's over. For more information on the hoax, see my article on the evolution of the hoax, or the Snopes.com page.
Note that the month or so after the opposition is also a good time to observe; although the planet will be starting to recede, it will be rising earlier in the evening than at opposition, which makes it easier for most people to observe it when it's high in the sky.
Q. What sort of equipment do I need to look at Mars?
A. Just about any telescope will do. I've seen some detail on Mars, during the 1997 opposition, with my 4.25" f/4 reflector, though that's certainly not an ideal planetary telescope. A good 6" f/8 reflector or 4" refractor should show a lot of Mars detail if the air is steady and if the telescope is in good collimation. I've also gotten excellent views of Mars through big dobsonian reflectors: although a clock drive is convenient for high magnification observations, don't let that stop you if you happen to have a dob. In 2003 I've done most of my observing so far with my homebuilt 8" dobsonian.
Binoculars won't show you any more than you see with the naked eye: just a bright red point.
Steady air and magnification are more important than telescope aperture, ultimately; you'll have the best luck when Mars is high in the sky, and it may help to find a location at high elevation or at least one where you're not looking over houses, cars or asphalt.
Q. Do I need filters to observe Mars?
A. No, but they can sometimes help in bringing out detail. They're especially helpful if you have an inexpensive refractor which has some chromatic aberration (meaning that it shows some colored fringes around bright objects): filters can dramatically cut down the color fringing. See specifics on the ALPO page.
Q. What can I see with a small telescope?
A. Hellas (a bright impact basin), some dark features like Syrtis Major, Mare Erythraeum, Mare Acidalium, and Niliacus Lacus, more subtle dark features like Margaritifer Sinus, Sinus Sabaeus, Lacus Solis (the "Eye of Mars"), and the polar caps.
With filters, you can sometimes see clouds and hazes of various types. With exceptional seeing, there are many other light and dark features which become visible, and you can look for details on the edges of the features, and for clouds over the Tharsis volcanos. You may even see parts of Valles Marineris, near Lacus Solis.
Sorry, you won't see canals -- there aren't any. But there's plenty of other stuff to look at!
Q: Why can't I see anything at all?
A: Mars is small. Really small. The details are smaller still. You really have to practice and have patience. The details will come, but don't expect them to be easy. Try for the polar cap first: that's usually the easiest to see. Then try to see some dark markings on the planet. The more you observe the planet, the more you'll learn how to see the detail on it.
Q. How can I train my observing skills?
A. Observe a lot -- start well before the opposition if you can, even if Mars is small or low in the sky. That way, by opposition you'll be ready to see all the detail which is there.
Also, try sketching the detail that you see -- even if you don't consider yourself an artist (I'm certainly not), sketching planetary detail really helps you think about what you're seeing, as well as being fun in its own right.
Q. Why do I see two polar caps, or none, when everybody says only
one is visible?
A. First, in some oppositions both polar caps are visible; in others, only one is.
Hellas, a light-colored impact basin (one of the biggest in the solar system) which tends to accumulate frost and haze and consequently appears very bright, looks more like a polar cap when it's near the limb than the real polar cap does. If it looks like you're seeing two polar caps, the other one may be Hellas. If it looks like you're only seeing one, it may be Hellas rather than the polar cap, especially during the Martian summer when the polar cap is unusually small and difficult to see.
If you're not seeing any polar caps, it may be that it's summer in the hemisphere pointing toward us, and the polar cap has shrunk to a point where it's hard to see.
Q. How do I figure out what part of the planet I'm looking at
and how it's oriented at the time when I'm looking?
A. That's one of the tricky parts of observing Mars, especially during this opposition when the polar cap is expected to be inconspicuous.
One way is to use a Mars globe, if you can find one (see the Links section for some suggestions).
The other, and easier, method of orientation is to use a computer program. See the software links below for programs which show Mars rotated correctly for a particular time and date.
Q. Can I see Mars' moons?
A. The moons should, in theory, be visible in large amateur telescopes (say, a 10" or so), but they're quite difficult, because they're very close to Mars and Mars is so bright its glare overwhelms the dim moons. Phobos is brighter, but Deimos is farther from Mars so might actually be easier to see. It helps to move Mars just out of the field, or to use an "occulting bar" in the eyepiece to block out the brightness of Mars. It's a challenge, but it's definitely possible!
... Mars Links ...
Older programs, no longer supported, but will still work if you can get a copy:
In some years I've put up detailed observing info for that particular year. Specifically: Mars 2007 • Mars 2005 • Mars 2003.