How to see planet Mars through a telescope
Last updated: 15th May 2020
For many amateur astronomers, Mars is one of the most intriguing planets to observe through a telescope. It’s a good astronomical target to practice on with your telescope (whether it be Newtonian, Dobsonian, Cassegrain, refracting, reflector, or quite simply your first ever instrument.)
Observing The Red Planet - An Introduction
Almost all year round, Mars can easily be seen with the unaided eye. When it is close to the Earth, the planet shines with a strong glow tinged with red, which helped to make it the embodiment of the god of war (Ares among the Greeks and Mars among the Romans). This characteristic colour is due to a strong presence of iron oxide in the Martian soil: rust!
Today, its observation is popular among amateur astronomers and the images from its exploration by scientific probes and rovers captivate the general public. Mars is indeed the closest celestial body to the Earth after the Moon and Venus, and a place where humans could consider moving to in the future… So much to stimulate the imagination!
When can you see Mars through a telescope?
It is important to wisely choose the best time to observe Mars in order to enjoy the best viewing conditions because its distance to us varies very strongly: from 56 to 400 million km! The most favourable moment is when Mars is in opposition: the time Mars is opposite the Sun in relation to the Earth, which happens every two years. Mars is then visible from sunset to sunrise and reaches its highest point (best field of view) in the sky in the middle of the night.
It is also the moment (within a few days) where the planet is closer to the Earth and is, therefore, best observable through a telescope of any type (Newtonian, Dobsonian, etc.).
However, this minimum distance can vary from 56 to 101 million km due to the elliptical orbit of the red planet and the respective periods of revolution of Mars and the Earth, which means that the opposition does not always occur where the two orbits are closest.
Mars was precisely in opposition last July, in a particularly favourable position since its distance from the Earth was only 57.7 million km (compared to 76.1 million km in 2016). This is the lowest distance since 2003 and such good positioning will not happen again until 2035.
When is Mars at its brightest in the sky?
The red planet reaches a peak magnitude about once every two years. In 2020, Mars will be gradually brighter starting from early February until November when its luminosity will slowly lower back to a normal level. The best time to view Mars in a telescope this year: from October 4th to October 17th.
After that, Mars will reach its highest magnitude again towards the end of 2021.
Did you know ?
- It’s a telluric planet with a tenuous atmosphere
- Fourth planet from the Sun
- Distance to the Sun: 207 to 249 million km
- Equatorial diameter: 6794 km (0.5 times that of the Earth)
- Revolution period: 687 days
- Rotation period: 24h 37min
How to find Mars with your phone
Nowadays, many stargazing apps for iPhone & Android can help you find planets, stars, comets and even satellites in just a few taps.
Simply hold your phone in front of you and move it across the sky – the app will update your screen in real-time and show you what’s in front of you.
You can’t find what you’re looking for? Simply use the search function and an arrow will appear to point you in the right direction.
Star Walk 2 – Apple Store / Google Play
Which telescope is best for observing Mars?
A home telescope of 60 to 100 mm in diameter with high magnification makes it possible to visualise the planet’s shape, but not much more. The best planetary telescopes usually feature a good focal length, and a decent aperture size is always helpful. It usually requires an instrument of at least 115 to 130 mm and a strong magnification (up to 150x) for the first surface details to be visible.
However, it is important to not underestimate what a 4″ scope can do. Many planetary observers use 4″ refractors very effectively to observe minute planetary detail. Patience and experience are paramount for planets observation. The red planet can be a very rewarding target to observe but it can also be very unpredictable: its own atmosphere has a huge influence on what details will be visible for you.
Among all the scopes that I’ve used, I have to admit that the refractors are a delight for planetary observing and suit my style which is more often than not short sessions with a quick setup. Binoculars that are well suited for stargazing can also deliver satisfying results if you are on a budget.
Important: Looking through a telescope takes a little bit of skill and practice. It will take time for your eyes to get used to the dark and seeing through the eyepiece of your telescope. Also, try to keep both eyes open. Cover the one you aren’t using if it is distracting. It is easier to keep your eye relaxed if you aren’t squinting one eye shut.
For those who do not yet have their own telescope, visiting your local observatory is usually a good starting point. They might regularly host stargazing parties and offer access to the more powerful instrument to the public as well as explain some element of astrophotography!
General Safety Guidelines When Using a Telescope
- Never look directly at the sun with a telescope (unless you have a proper solar filter on).
- Never use a telescope to project an image of the sun onto any surface. Internal heat build-up can damage the telescope and any accessories attached to it.
- Do not leave the telescope unsupervised, especially if children are present.
- We recommend you allow your eyes at least 10 minutes to adjust to the dark conditions needed to use the telescope at night.
- Wear suitable warm clothing if needed and have a torch to navigate yourself through the dark
- Assess the strength of the wind. Do not use the telescopes in strong winds.
What does Mars look like through a telescope?
As you will see from the pictures below, even an amateur telescope reveals some nuances of its rocky soil and surface details. Large characteristic formations are visible and appear in the form of dark expanses, as for example Syrtis Major which owes its colour to rocks resulting from volcanic activity. On the other hand, other areas are clear, like the Hellas Planitia impact basin, because of the dust raised by the Martian winds.
Another peculiarity of the red planet: the possibility to see ice scopes at the poles! Last year, the southern polar cap was visible even with lower-end telescopes.
Pro-tip: It’s good to set up your telescope on a tripod and leave it out for 10-15 mins so the different parts and optics (primary mirror) inside your instrument adjust to the outside temperature.
Mars comes around every two years and two months but only every 15-17 years will it be at its most favourable position, and even then it will usually look about half the size of Jupiter through a telescope. To increase the chance of a good observing session, I usually plan my planetary stargazing sessions in the evening twilight or morning twilight provided any are up.
Purely from an image scale factor, a greater telescope magnification is always desired for Mars to show things just that little bit bigger for those who have a less experimented set of eyes.
Telescope views of Mars
2-inch telescope
This is one the smallest aperture size and usually a telescope for people starting their stargazing journey. Unfortunately, you won’t be able to resolve a clear image of the red planet at this size. At best, you will see a bright disc with a reddish hue.
4-inch telescope
At this size, your telescope aperture will collect a little bit more light and thus give you a view of Mars worth seeing. To improve the image further, you may want to use an eyepiece that increases magnification between 120x to 200x.
8-inch telescope
A telescope of this size would definitely be a good upgrade for planetary observation. In perfect conditions, it could even handle 300x magnification which would greatly help seeing finer details on the planet surface. It would be worth adding an orange filter onto the eyepiece in order to make the darker features of the planet stand out more against the orange background.
10-inch telescope
A much better size for planetary observing. The planet will show much more feature, including some dark markings and the north polar cap. If you are observing Mars at its closest position to Earth and granted you have a steady atmosphere above you, think about trying a 2x Barlow lens in order to improve your visual experience that little bit further.
Related: Check out our guide on how to purchase your first telescope.
Galileo's Tips & Tricks
A red filter will lighten the desert regions of Mars and darken the rest of the planet.
A green filter will enhance the overall contrast of the image.
Can You See Mars Without a Telescope?
Mars is one of the 5 planets that can be seen without a telescope. At certain times during the year, you can see more than one celestial bodies in the sky at the same time.
During favourable times, Mars appears as a very bright star tinged with red. The planet is visible for much of the year, except for short periods of time when it is too close to the Sun to be observed.
If you are observing without optical instruments, it is, of course, impossible to discern any details on Mars as you would with a refractor or a reflector telescope. In general, planets appear like stars to the unaided eye. On the other hand, Mars will appear a lot more prominently during opposition and look like a star with a reddish hue, offering beautiful visual pictures when it gets closer to the Moon. Even with binoculars, its interest remains limited, with no extra details being visible.
Frequently asked questions:
#1 Can you see Mars through a telescope?
Ans. The red planet is one of the closest planet to Earth so it is fairly easy to observe through a home telescope.
#2 Is Mars visible without a telescope?
Ans. You can easily spot Mars without a telescope depending on the light pollution in your area. It looks like a star with a reddish hue.
#3 How big of a telescope do I need to see Mars?
Ans. You can observe Mars with an entry-level telescope (3-inch) and be able to distinguish its shape and colour. Through an 8-inch telescope, you’ll be able to make out surface features.
Interesting Fact About Mars
If you observe Mars repeatedly and diligently, know that thanks to a longer rotation period that of the Earth, a given area will be visible every night at the same place but about forty minutes later than the day before. Which also means, if you observe the planet with a telescope every night at the same time for 36 days in a row, you can observe all of its surfaces! Pretty cool, right?
Icon source: Icon8
More Planets to Observe
I have been an avid stargazer for over 15 years. The night sky is a treasure trove of celestial wonders that I will never stop looking up to. From planets and galaxies to nebulae, I feel incredibly lucky to have been able to observe them with my own eyes, and I hope to help others do the same.