By Nalayini Davies
Mars is the only planet whose surface details can be observed from Earth – Mercury is too small and all the others are covered in clouds.
And Mars is especially photogenic during opposition because it can be seen fully illuminated by the Sun when viewed from Earth.
Although you’ll need a telescope to observe the surface features of Mars, the easy to use, portable and cost-effective “Dob” – the Dobsonian design Newtonian telescope - is all that will be required.
To see Mars, we recommend our best-selling telescope – the 8” Dobsonian
With this, you will see the various surface features of Mars as the planet rotates and presents different aspects of its surface.
Location in the Solar System: 4th planet from the Sun, Earth’s immediate neighbour with its orbit lying just outside that of Earth’s.
The Size of Mars: Diameter of 6, 792 km, and at just over half that of Earth it is the second smallest planet in the solar system.
Average Distance from the Sun: 227.9 million km (Earth is 150 million km from the Sun).
Axial Tilt: 25.2 degrees (Earth: 23.5 degrees).
Time Taken to Orbit the Sun: 687 Earth days (Earth takes 365 days).
Furthest Distance from Earth: 401.3 million km.
Nearest Distance from Earth: 54.5 million km (on 31 July 2018: 57.6 million km).
Time Taken to Rotate: 24 hours 37 minutes and 23 seconds (Earth takes 23 hours and 56 minutes).
Greatest Apparent Magnitude: -2.9 magnitude (same as Jupiter at its brightest). On 27 July 2018: -2.8 magnitude.
Greatest Angular Size in the Sky: 25.1 Arcseconds (there are 60 arcseconds in an arcminute and 60 arcminutes in a degree and your little finger held at arm’s length covers one degree of sky). On 31 July 2018: 24.3 arcseconds.
Number of Moons: 2, Phobos and Deimos.
Naked-Eye to see the distinct orange-red colour of Mars and how it compares to other celestial objects in the sky both in brightness and colour.
Binoculars will only show an orange dot of light with no better viewing than naked-eye, so Mars in not a binocular object.
Telescope of 6” or greater aperture will show the features of Mars.
Mars is a beautiful naked-eye object, easily seen with a striking orange-red colour. It will also help trace the ecliptic (the apparent path of the sun and the planets in the sky) by first locating Mars and then planets Jupiter and Venus which are the other two brightest objects in the night sky at this time. Slightly less bright Saturn and early setting fainter Mercury i.e. all 5 naked eye planets are all present in the sky and can be traced through the ecliptic found through Mars.
The rusty red colour of Mars is the result of large quantities of iron oxide (i.e. rust) in its surface rocks.
Mars is the only planet whose surface details can be observed with a telescope from Earth – Mercury is too small and all the others are covered in cloud.
The bigger the aperture the more detail you can see so a 10” reflector telescope shows more than an 8” and an 8” shows more than a 6”. The greater the magnification, the better the viewing so the use of an additional Barlow lens in conjunction the two lenses of the telescope (one is for greater magnification and the other one offers a wider field of view) would enhance the experience.
Telescope viewing can reveal Martian features such as white polar caps and volcanic plains. The polar ice is mostly frozen carbon dioxide and the extent of it varies with Martian seasons resulting from its 25-degree axial tilt.
The image of Mars will be upside down through a Dobsonian telescope, so uppermost in view will be the South Pole.
With repeated and committed viewing, Syrtis Major, Mars’ most prominent dark surface marking (a “V” / triangular shape) is also observable. This is a sloping area of darker sub-surface rock that is periodically and temporarily partly covered by paler dust.
The atmospheric pressure on Mars is less than 1% of Earth’s mean sea level pressure. Mars’ atmosphere is also significantly thinner. This leads to even the slightest of breezes on the surface resulting in dusty whirlwinds of surface soils. Such dust storms on Mars can obscure the surface markings but these storms are more common when Mars is closest to the Sun.
As Earth rotates about 40 minutes faster than Mars, over a period of a few weeks it’s possible to see much of Mars’ surface, and this provides more opportunities to see surface features potentially missed during earlier observations.
Changing Views of Mars through Telescope Image credit: NASA
Observing from a dark site under clear moonless skies it is also possible for a committed observer to see the Martian moons, Phobos (+10.5 magnitude) and Deimos (+11.6 magnitude).
When observing through telescopes, the use of filters can sharpen details.
A Barlow lens will help with magnifying the image so you’ll see more detail.
The use of filters will enhance the viewing and a wide range of colour filters are suitable (e.g. Green or Blue filter will enhance the polar caps and a Red or Orange filter will enhance the darker details like Syrtis Major).
One “sees” as much as one “knows”, so using an astronomical guide book will improve your knowledge and through that enhance the observing experience.
The Astronz introduction to imaging theplanets. Great for Mars, Jupiter and Saturn.
Sketches made by Auckland Astronomical Society Member Andy Cho have captured Syrtis Major and the polar caps respectively during the less close 2016 Mars opposition.
Syrtis Major on Mars Image Credit: Andy Cho Polar caps on Mars (Image Credit: Andy Cho)
Astrophotography by Auckland Astronomical Society Member Rolf Olsen from Auckland in November 2015 has captured the surface markings
Surface markings and Storm on Mars (Image Credit: Shaun Fletcher)