The Major Surface Features of Mars

Introduction

Mars is a fascinating planet!

And not just because it is our neighbor in the solar system.

Although Mars is smaller in size when compared to Earth, it boasts some of the largest surface features among the planets in our system.

From its vast distance, we often see it as a red, smooth dot. But, with craters and canyons and volcanoes filling its surface, Mars hardly fits that image when you get up close, as we will soon learn. 

Observing Mars is a challenge because when the planet itself is in a favorable position, there are other obstacles to our seeing. For example, clouds and dust storms can obscure observations, and poor telescopes will not show you the details.

In this article, we will learn the various surface features on Mars, which ones can be seen with telescopes (don’t worry, we will also tell you the best telescopes to see Mars) and the points you need to remember to make the most of your observing experience. 

Ready for a ride of the Martian world? Let’s go! 

A view of planet Mars from space
Planet Mars (source)

Surface Features of Mars

The first, and most notable, feature of Mars is its red-colored surface, which is caused by oxidation of iron (III)

On first look through a telescope, the Martian surface broadly consists of bright and dark regions. The lighter regions are covered by dust, whereas the darker areas are where wind has swept the dust to reveal the underlying rocky surface.

The Martian surface is dotted with 43,000 craters. These have remained intact for many years due to the lack of tectonic activity, stable crust, and low erosion rate.  

There are also 20 large, old volcanoes, including Olympus Mons which is the largest in our solar system. 

The north and south poles are covered with ice, made mostly of carbon dioxide with underlying water-ice content. 

Vast, deep systems of canyons streak the red planet’s surface. Moreover, scientists believe that water once flowed freely on the Martian surface, since the hematite and goethite only form in liquid water. 

A map of major surface features on Mars from Hubble
A Hubble portrait of Mars (Source)

In addition to these relatively permanent features, Mars also hosts seasonal features such as global dust storms and clouds. These spike during summer because Mars’ orbit takes it closer to the Sun, thus increasing the temperatures. 

Martian Features You Can See With a Telescope 

Mars has several interesting features on its surface which a telescope can reveal, especially when Mars is near us at opposition. With a medium- to large-sized telescope, you can observe the Olympus Mons volcano, polar ice caps at each Martian pole, and even the canyons such as Valles Marineris.

Mars’ overall diameter of 4,219 miles (6790 km) is a little more than half of Earth’s size of 7,923 miles (12,750 km). Although it is Earth’s neighbor in the solar system, its smaller size makes some of the features difficult to observe.

What details you see on Mars with a telescope also depends on the model you are viewing with, as we will learn later in this section. At a minimum, a 4-inch telescope aperture size is required to comprehend Mars’ red color.

During oppositions, which is usually the best time to view Mars, the dark regions on its surface come into focus as well. 

With telescopes of aperture sizes between 6 and 8 inches, more planetary details like the planets’ clouds and their colors are visible (even when there is no opposition occurring). 

Telescopes 8 inches and above reveal clearer and sharper views of Mars, including, with a lot of effort, its moons Phobos and Deimos.

The table below gives a sense of which features are visible with a telescope and what you should expect to see.

FeatureMartian Coordinates Small Telescope(up to 5 inches)Medium Telescope(5 to 8 inches)Large Telescope(8 inches and above)
Polar Ice CapsPolesUnfocused white dotsVisibleVisible
Olympus Mons19°N 226°ENot visibleVisible as a dark spot during oppositionVisible
Valles Marineris14°S 59°WNot visibleDifficult. At opposition onlyVisible
Vastitas Borealis88°N 33°ENot visibleNot visibleVisible
Syrtis Major Planum8°N 70°ENot visibleVisible as a dark spotVisible
Dust StormsNANot visibleVisibleVisible

We’ll now look at each of the features above in more detail, except dust storms, which are covered in a separate article.

Polar Ice Caps

Overview

The ice caps at each Martian pole are caused by the planet’s tilt of 25 degrees, which is comparable to Earth’s 23.5 degrees. This gives Mars seasons similar to Earth, although the summers and winters on Mars are more extreme.

A view of the North Polar ice cap on Mars
The Martian North Pole (source)

During Martian winters, the poles are in complete darkness and the temperatures also drop to -153 degrees Celsius or -243 degrees Fahrenheit

Due to this, the carbon dioxide that is normally present in the atmosphere condenses as snow, forming a seasonal ice cap. Clouds also start developing over these regions, causing the cap to grow for latitudes up to 55 degrees in the north and 50 degrees in the south. 

When summers come around, the CO2 layer sublimes back into the atmosphere, leaving behind a tiny patch of a mixture of sand, dust, and water ice, called the residual ice cap.  

How to See the Polar Caps With a Telescope

Martian polar caps are the easiest feature to identify. Their location is at the poles (top and bottom) of Mars… pretty easy, right? 

Telescopes below 6-inches will only result in fuzzy views. Use a 6-inch scope and a 50x magnification to view the poles during opposition. Since Mars is tilted, you will typically be able to see only one pole at a time

If you are using a large telescope, you should be able to spot the ice caps relatively easily.

Olympus Mons

Overview

The now silent Olympus Mons is a shield volcano, one that consisted entirely of lava flows. 

At 624 km in diameter and 25 km high, it is the largest volcano in our solar system (Mt. Everest on Earth falls a long way short at 8.8 km!). In fact, it is so huge that even if you were standing on Mars, you would not be able to view it in its entirety because of the planet’s curvature.

It resides at the edge of the Tharsis Montes region, which is known for its large number of volcanoes that are up to 100 times bigger than those on Earth. 

The weak gravity on Mars led to high eruption rates early during the planet’s history and the accumulating of them over very many years. 

Olympus Mons from high in the Martian atmosphere
Olympus Mons (source)

How to See Olympus Mons With a Telescope

Olympus Mons resides at 18.65°N 226.2°E on the Martian surface, in Mars’ western hemisphere. 

It is not visible with small telescopes but can be seen as a dark region with medium and large scopes. This region also attracts a lot of orographic clouds, which are usually used as a landmark to spot Olympus Mons within the Tharsis region. 

Note that these clouds, when they appear, will block your view of Olympus Mons.

Valles Marineris

Overview

We mentioned earlier that Mars hosts systems of canyons. Valles Marineris is one such system, and one of the largest canyons in the solar system. 

The entire system, which extends along the equator of Mars, starts in the Tharsis region to the east and ends in a western outflow region in Chryse Planitia. 

It is thought to have formed during the thickening of Mars’ crust and later widened. It is 4,000 km long in total, 200 km wide, and 7 km deep. In fact, its length is equivalent to that of the United States! 

How to See Valles Marineris With a Telescope

It is very difficult to see Valles Marineris with small- and medium-sized telescopes. With large telescopes, Valles Marineris is visible as a dark line near Mars’ equator. 

Vastitas Borealis

Overview

Famously known as the northern plains, Vastitas Borealis is the largest lowland region on Mars. 

Centered at 87.73°N 32.53°E on the planet’s surface, the region is patterned with chains and polygons. These are a result of the ice which is present in the soil reacting to drastic temperature fluctuations. 

During summers, as this ice melts, the dark soil present underneath is revealed. 

How to See Vastitas Borealis With a Telescope

It is not possible to observe Vastitas Borealis using a small or medium telescope. We recommend a large one. 

From the given coordinates, you’ll be able to spot Vastitas Borealis in the northern latitudes of Mars near Planum Boreum. From there, it spans 1,500 km towards the south.  

Syrtis Major Planum

Overview

Syrtis Major Planum is another shield volcano (like Olympus Mons) and one of the darkest regions on the planet. As with other dark regions on Mars, Syrtis Major too consists of basaltic volcanic rock. 

It lies in between Mars’ northern and southern hemispheres, and spans 1,000 km from west to east and extends 1,500 km north. This feature also hosts many seasonal variations, where sand dunes migrate on the planet’s surface, roughly 0.5 meters per year.  

The Syrtis Major Hemisphere on Mars
The Syrtis Major Hemisphere (source)

How to See Syrtis Major Planum With a Telescope

Syrtis Major is centered at 8.4°N and 69.5°E, on the west of Isidis Planitia. It is not visible with a small telescope.

With a medium- or large-sized telescope, you’ll find it as a dark spot roughly 1,500 km from the Martian equator. 

How To See the Martian Features

While a telescope of 6-inches and up will give you relatively good visibility of the Martian surface, consider using filters to enhance your observing experience. Filters work by improving the contrast between the feature you are trying to observe and its background. 

Red and orange filters highlight the Martian polar ice caps and their boundaries. They also increase the contrast of the darker regions such as Valles Marineris. These are best to spot dust storms boundaries as well (note that dust storms are a common occurrence on Mars, and obstruct observations when they arise).

A green filter increases the overall contrast of the planet with which extensions of polar caps come into view. Martian clouds can be viewed with a blue or violet filter.

When to See the Marian Features

Although all of these features are interesting, they are not always visible. The quality of your observations will depend heavily on where Mars is in its orbit, which of its sides is facing Earth, and the specific features that are visible on that side. 

Mars’ Orbit and Rotation

The red planet rotates once every 24.5 hours, which means that the same side will be facing Earth for many consecutive days. Due to this, it is best to plan your observations on days that are further apart with varying times to detect a broad range of features. 

The fact that Mars is next to Earth in the solar system means that, in its orbit, the distance between two planets varies widely. It ranges between 56 million km when they are closest and over 400 million km when they are opposite to each other. 

Mars approaches the closest to Earth during oppositions that happen every 26 months and is visible the brightest in the months leading up to the opposition and up to one month after it. Around this time, it reaches its highest in the sky at midnight

Also worth noting is that both Earth and Mars rotate in the same direction, so your features will appear to move left to right unless you are using a mirror-reversed telescope, in which case they will move right to left. 

Ideal Telescopes to See Planet Details

While details about Martian orbit are important to remember, your observation tools play an important role as well. 

Telescopes with a small field of view are preferred since they fill the eyepiece with the planet’s light and not the background sky. 

A helpful tip is to remember that as focal length increases, the field of view decreases, which means you should be aiming for telescopes that have higher focal length and a slower focal ratio. Models with a focal ratio of f/8.0 and above are ideal for planetary observing.

Whichever telescope you choose, if you wish to see Mars in more detail, you will need to push for greater magnification. In effect, that means a larger aperture. You’ll more detail with a big scope than with a smaller one, because it collects more light which tolerates higher magnification levels.

Maps of the Martian Surface

Using data from the Mars Global Surveyor, the map of the Martian surface reflects 600 million measurements to depict the names and locations of various features. You can find a version of it here.

Google Mars 

I wish we could all travel to Mars. Since that is not possible at the moment, we will make do with Google Mars, which allows us to visit Mars (in 3D!) while remaining on Earth. 

It was launched in 2009 by NASA and Google and features data collected from the Mars Global Surveyor.

The website is filled with useful resources that explain Mars’ surface features, the spacecraft that visited it, dunes, craters, and canyons among others. 

You can also view the map in either visible or infrared view; each highlights features in a different way. 

Summary

Martian features are fascinating to know but sometimes frustrating to observe. We recommend a minimum of a 6-inch telescope since anything below that will not reveal great detail. 

The best time to hunt for major Martian features is when the red planet is at Opposition since Mars is brightest and biggest around this time. Future opposition windows are a month or two on either side of October 2020, December 2022, January 2025, and February 2027.

Keep in mind that dust storms are a common occurrence on Mars and could obscure your observations for days on end. 

However, when you do have a good view of the surface, consider using filters to enhance the feature you are trying to observe.

As with any observation, patience and a bit of luck are also necessary. 

Happy observing!


Written by Sharmila Kuthuner