The Ultimate Guide to Observing Mars

Beyond Earth's orbit lies the fourth planet from the Sun, Mars—a small, mysterious planet that has intrigued humanity for centuries. With its eerie, fiery, reddish appearance in the night sky, Mars often looks like it is preparing for battle, so it was fittingly named for the Roman god of war.

Unlike Venus and the outer planets covered in clouds, Mars shows surface detail when viewed through a telescope. Nineteenth-century astronomers noticed its surface was marked with crisscrossed lines resembling irrigation "canals" and ever-changing seasonal polar ice caps. These markings caused many to speculate that there could be intelligent life on the planet.

For the amateur astronomer, seeing Mars in the sky and observing Mars through a telescope can be as thrilling as collecting data from professional spacecraft and rovers scouring its surface and making discoveries. Best of all, you can do it right from your backyard! This guide will help you understand Mars and why it is such a favorable target. We'll provide interesting Mars facts, equipment recommendations, methods for capturing your Mars images, surface features to look out for, observing tips, and more.

Interesting Facts About Mars

	Mars is often called the "Red Planet" because of its reddish appearance, which is due to iron oxide, or rust, on its surface.
	In Roman mythology, Mars was the god of war and agriculture and the protector of Rome.
	Mars is about half the size of Earth, with a radius of 2,106 miles (3,390 kilometers). It has an elliptical orbit, so its distance from the Sun varies. At its closest point, known as perihelion, Mars is about 128 million miles (206 million kilometers) from the Sun. At its farthest point, called aphelion, Mars is approximately 154 million miles (249 million kilometers) away from the Sun.
	A Martian day is known as "sol," 40 minutes longer than a day on Earth. However, a year on Mars is nearly twice as long as an Earth year, lasting 687 Earth days.
	Mars has seasons like Earth due to its 25-degree axial tilt. However, Seasons last longer on Mars because the planet takes longer to orbit the Sun.
	Mars is home to the largest shield volcano in the solar system, Olympus Mons. It is over 21.9 km (13.6 mi; 72,000 ft) high, as measured by the Mars Orbiter Laser Altimeter (MOLA). Mars also features a massive canyon system named Valles Marineris, over 4,800 kilometers (3,000 miles) long. The planet's surface is covered in dust and rocks, with evidence of ancient river valleys and lake beds, suggesting that liquid water once existed there.
	Mars has two irregularly shaped small moons in orbit, Phobos and Deimos. Both are thought to be captured asteroids and heavily cratered. American astronomer Asaph Hall discovered the moons in 1877. Phobos is the larger moon, orbiting Mars three times a day. It is 17 miles across and orbits an average distance of 3,700 miles from the planet's surface. Phobos is gradually moving closer to Mars at a rate of about 6 feet every century. Scientists calculate that in 50 million years, Phobos will either crash into Mars or break up into a ring around the planet. Deimos is the smaller moon, orbiting Mars about every 30 hours. It is 9 miles long and orbits at a distance of approximately 12,500 miles from Mars.
	Scientists believe that 4 billion years ago, Mars had enough water to cover its entire surface 140 miles deep! Today, most of the water on Mars exists as ice, primarily at its polar ice caps, with a seasonal layer of carbon dioxide on top. Evidence of Mars's seasonal briny (salty) water flows also exists. Dark streaks, known as recurring slope lineae (RSL), appear on Martian slopes during warmer seasons and fade as they get colder. Scientists believe the presence of hydrated salts in these areas may suggest that liquid water is involved. Water on Mars is crucial for human exploration, as it can be used for drinking, growing food, and producing fuel! The presence of water on Mars in the past and present suggests that the planet may have supported microbial life, although no definitive evidence has been found. Let's keep our fingers crossed for future Mars missions to make more exciting discoveries.
	Mars's atmosphere is unique compared to Earth's. It's very thin, cold, and composed mostly of carbon dioxide (about 95%), with small amounts of nitrogen (2.7%) and argon (1.6%). The atmospheric pressure on Mars is less than 1% of Earth's. The median surface temperature is -85°F (-65°C). Due to Mars's thin atmosphere, heat easily escapes. Temperatures on the Red Planet range from the 70s°F (20s°C) at the equator to -225°F (-153°C) at the poles. Mars's atmosphere undergoes seasonal changes, with carbon dioxide freezing at the poles during winter and sublimating back into gas in the spring. Unlike the reddish sunsets on Earth, sunsets on Mars appear blue due to the unique way the Martian atmosphere scatters sunlight. The Martian atmosphere contains fine dust particles that are the right size to scatter blue light more effectively than red light, called Mie scattering.
	Although Mars has clouds, they differ from Earth's. Mars has water ice clouds, similar to Earth's cirrus clouds, but thinner. Carbon dioxide (CO2) ice clouds form when cold enough that the Martian atmosphere freezes locally. These clouds are typically found at higher altitudes and can be quite beautiful, often appearing as wispy clouds filled with ice crystals that scatter light from the setting sun. Some even shimmer with colors, creating captivating displays! Dust clouds also form when hot air rises, carrying dust, cools, and sinks. The dust cells that form have a similar granular pattern to Earth's clouds, but they are made from dust instead of water.
	Mars experiences frequent dust storms. Solar heating occasionally raises pockets of warm air during summer, causing strong winds. As a result, dust storms form that can cover much of the planet, obscuring its surface and lasting for several weeks, creating a "global dust storm." Much of its dark surface markings disappear when Mars is viewed through a telescope during a dust storm.
	Mars's dust devils are quite common and similar to Earth's but can be larger (8 kilometers, 5 miles) and widths up to 700 meters (2,300 feet) due to the thinner Martian atmosphere. They form when the Sun heats the surface, causing warm air to rise through cooler air above, creating an updraft. Horizontal winds then cause this rising air to spin, forming a vortex that lifts dust from the surface. Martian dust devils can be larger in size and height than Earth's dust devils, but the overall force exerted by a Martian dust devil is weaker than an Earth dust devil of comparable size. Although they can threaten equipment and landed spacecraft, dust devils have also been known to be beneficial. Between 2007 and 2008, dust was periodically removed from the Mars rover Spirit's solar panels, enabling it to function longer than anticipated.
	Mars is considered one of the most explored planets in our solar system. Numerous missions to the Red Planet have been successful like Mariner 4 (1965), Viking 1 and Viking 2 (1976); Mars Pathfinder and Sojourner Rover (1997); Mars Global Surveyor (1997; Spirit and Opportunity Rovers (2004); Mars Reconnaissance Orbiter (2006); Curiosity Rover (2012); Insight Lander (2018); Perseverance Rover and Ingenuity Helicopter (2021); Tianwen-1 (2021); and Hope Orbiter (2021). Let's look forward to future Mars missions, including Mars Sample Return (MSR) and Human Missions to Mars within our lifetimes.

Understanding Mars Opposition

Earth and Mars travel around the Sun in oval-shaped or elliptical orbits; neither planet's orbit is a perfect circle. As a result, the distance between the two planets varies greatly. Mars Opposition occurs when the Earth catches up to Mars in their respective orbits and is placed between the Sun and Mars. The Sun and Mars appear on opposite sides of the Earth. So, from our viewpoint, Mars rises in the east as the Sun sets in the west and remains visible all night. Mars Opposition occurs about every 26 months. The next Mars Opposition occurs on January 16, 2025. On this date, Mars appears in the constellation Gemini, and its orange/reddish disc will appear larger and brighter in the night sky, reaching an apparent diameter of about 14.5 arcseconds and shining at magnitude -1.4.

A close Mars Opposition occurs every 15 to 17 years when Earth passes between Mars and the Sun near Mars' perihelion (its closest point to the Sun). In 2003, Earth and Mars were at their closest in nearly 60,000 years, with a distance of less than 35 million miles. Mars appeared impressively large, with an apparent diameter of 25 arcseconds and a brightness magnitude of -2.8. In contrast, Mars can be 62 million miles from Earth during less favorable oppositions. Mars' orbit will continue to recede away from Earth's orbit as they circle the Sun. Mars' size will appear smaller during future oppositions through 2027 before its orbit begins to close in on Earth's orbit again for the next cycle.

How to find Mars?

How can you find Mars? Well, suppose you have followed Mars since last year's Opposition. In that case, you will probably know Mars is still visible in the night sky and is currently in the constellation Cancer but is moving towards Gemini, where it will be in Opposition. For the rest of us, star charts in astronomy-related magazines or websites are helpful visual guides to spot Mars.

Today's most modern and informative tools are in astronomy apps such as Celestron's SkyPortal Powered by SkySafari™ Mobile App. This full-featured planetarium app is included with the purchase of any Celestron telescope, available from the Apple App Store or Google Play. SkyPortal instantly provides new telescope owners with information, including audio and written descriptions about Mars. It also provides celestial coordinates, a real-time sky map, rise and set times, and physical and orbital parameters.

The best equipment for viewing Mars

Telescopes:Any small telescope with an aperture of 60 mm to 90 mm can reveal some surface markings on Mars about a month before, during, and after Opposition, although the image scale will be small and the resolution somewhat limited. Telescopes such as Schmidt-Cassegrain and Maksutov-Cassegrain telescopes (seven inches and up) are our best picks for planetary observing due to their increased light-gathering ability, longer focal lengths, and ability to accommodate higher magnifications (150x or more) on a night with steady seeing.

Resolution is a function of aperture, so consider using a larger telescope to observe prominent features on the Martian surface. The larger the telescope's mirror or lens, the more light it will collect, but the heavier the telescope will be. You should carefully consider how much weight you can handle and if your budget allows.

Filters: Color filters are a great way to enhance subtle features on the Martian surface and its atmosphere for a more enjoyable observing experience. Filters can individually thread onto the end of eyepiece barrels or be stacked together to enjoy the benefits of multiple filters at once. (Please note that when you stack filters, light is diminished. Doing so is only advisable with telescopes with at least 8" of aperture.) Here are the most popular color filters for enhancing details on Mars:

• #80A Blue Filter - Enhances atmospheric clouds.
• #58 Green Filter - Excellent for increased contrast of Martian polar caps, low clouds and yellowish dust storms.
• #56 Light Green Filter - Increases contrast of Martian polar caps, low clouds and yellowish dust storms.
• #25 Red Filter - Ideal for observing the polar ice caps and features on the Martian surface. Sharpens the boundaries of yellow dust clouds.
• #21 Orange Filter - Reduces light from the blue and green areas that darken the maria, oases and canal markings, while lightening the orange-hued desert regions. It also sharpens the boundaries of yellow dust clouds.
• #12 Yellow Filter - Reduces light from the blue and green areas that darken the maria, oases and canal markings, while lightening the orange-hued desert regions. It also sharpens the boundaries of yellow dust clouds.
• #21 Orange - Increases contrast between light and dark features and penetrates hazes and most clouds.

Color filters are available in the following Celestron products:

A Variable Polarizing Filter - 1.25” #94107 can be adjusted to reduce light transmission and is beneficial for reducing glare.

Cameras and Phone Adapters: Smartphones’ built-in cameras are getting better and better. You can hold your phone up directly to the telescope’s eyepiece to take advantage of the telescope’s image scale with higher magnification to capture plentiful detail, but only when Mars is in a favorable position. You have the option of using the smartphone’s digital zoom feature to increase the size of the planet to your liking.  It can be tricky to properly center your target, but by using a smartphone adapter, centering Mars will be quick and easy.

DSLR cameras are another popular tool you can use to capture Mars. You will need a T-Adapter (there are different models available for your telescope), and a camera-specific T-Ring (i.e., Canon, Nikon, etc.). The T-Ring attaches to your camera’s bayonet, and the T-Adapter threads onto the T-Ring. Depending on the T-Adapter you are using, it will either slide into the eyepiece drawtube, or screw directly onto the telescope’s rear cell.

Planetary imaging cameras are also a great way to capture high-resolution images with tremendous detail. The camera takes the place of your telescope’s eyepiece and connects through a USB cable to your computer or laptop. Software analyzes each frame of the live video capture and throws away the images that are blurry due to poor atmospheric turbulence. It then stacks and perfectly aligns the clearest video frames to create a bright, detailed, colorful image.  Celestron’s planetary imaging cameras include:

What to look for while observing Mars?

Mars often reveals subtle changes from Opposition to Opposition, but every so often, a significant change does occur. In 2018, a massive global Martian dust storm engulfed the planet and limited the amount of visible detail. This storm caused NASA's Opportunity rover to suspend operations due to the lack of sunlight for its solar panels. The storm was so intense that it led to the end of Opportunity's mission. Currently, the surface is much clearer. For the best views, a larger aperture telescope and patience to find just the right time when the air settles and details pop into view. So, what prominent Martian features should we look for during and after the Opposition?

	Phases Although Mars does not exhibit the full range of phases seen from Earth, it almost always appears in a gibbous phase, leading up to a full phase at Opposition.
	Polar Ice Caps Like the polar ice caps on Earth, Mars has ice caps at its poles that grow or wane with the season. They are much smaller and thinner than the Earth's ice caps and made from frozen carbon dioxide (dry ice) and water ice, which lies beneath.
	Land Formations Unusual dark surface formations on the Martian surface were named after seas or lakes. These maria appeared to change shape over time, but it was later learned these markings did not actually change but were periodically covered in dust and sand. Look for these large ancient volcanic "seas" such as Syrtis Major, Mare Tyrrhenum, and Mare Cimmerium. There are also smooth areas that were once thought of as continents. Look for Hellas Planitia impact basin and Arabia Terra. Both appear to be covered in Martian dust. Olympus Mons is the largest volcano in the Solar System and roughly the size of the state of Arizona. Although you are unlikely to see it in a telescope, you might be able to spot the high-altitude clouds covering its location named Nix Olympica. One of the largest canyons in the solar system is Valles Marineris. It is so large that it dwarfs our own Grand Canyon! This Martian canyon is one of the largest canyons in the Solar System and can be seen through a telescope as a dark scar across the planet's surface.
	Dust Storms As mentioned earlier, dust storms can cover much of the planet, obscuring its surface detail and lasting for several weeks, creating a "global dust storm." Many of Mars's dark surface markings disappear when viewed through a telescope.

Observing Challenge: Although they are very tiny, you may be able to spot the two orbiting moons of Mars, Phobos and Deimos, if you're up for a good observing challenge. While their proximity to the overwhelmingly bright planet may make them challenging to see from the glare, it can be done. You will need access to a large telescope 11" in aperture or greater, excellent viewing conditions, patience, and luck.

Occultations and Conjunctions

In 2025, Mars will be visible for much of the year, especially around its Opposition on January 16. During this time, Mars will be at its brightest and most prominent in the night sky, making it an excellent viewing target to showcase to your family and friends. However, Mars will also be joining up with other celestial bodies during the year that are noteworthy:

Lunar Occultation: On January 13, 2025, the Waning Gibbous Moon will pass in front of Mars, creating a lunar occultation visible from parts of the Americas and Africa. Although the occultation will only be visible across part of the world, viewers outside the occultation boundary will still witness a close conjunction between the pair will be more widely visible. Check your astronomy-related apps for the disappearance and reappearance times for your area. On February 9, 2025, another lunar occultation of Mars will occur over high latitudes in regions of Russia, China, Canada, and Greenland, but will not be seen from the United States.

Conjunctions: On October 21, 2025, Mars will be in conjunction with Mercury, separating at about 2 degrees. Look low in the southwest after dusk. Another closer conjunction of Mars and Mercury will occur on November 12, 2025. This time, the planets will be separated by about 1.18 degrees. Look low in the southwest after dusk.

Occultations and Conjunctions provide fun viewing opportunities for amateur skywatchers, so mark your calendars and enjoy the show!

Helpful Observing Hints

We hope this guide helped you get better acquainted with Mars. While observing our nearest neighboring planet, you may imagine a day when humans finally stepped foot on its surface. Do not forget to reflect that there are intelligent rovers already on Mars (both alive and dead) that originated from Earth, several orbiters circling the Red Planet, and other missions being planned. Perhaps SpaceX's Starship and NASA's upcoming human exploration missions will deepen our understanding of the Red Planet and pave the way for human settlement like in a science fiction movie. Perhaps one day, Mars will reveal more of its secrets and answer the age-old question, "Is it hiding something?"

To learn more fun Mars facts, please click here.

Have a great time exploring Mars! Clear skies! 

Other articles you might be interested in: Ultimate Guide to Observing the Universe