This autumn, Mars comes close to Earth, so it will be very obvious in the sky. It’ll be easy to spot in the evenings – just look toward the south, roughly halfway up from the horizon, and you’ll see it as the brightest thing in the sky, other than the Moon or any planes that happen to be around.
Mars at its closest is brighter than any star, and brighter than any other planet apart from Venus – and that is in the morning sky at the moment anyway. You’ll also notice its colour. Although we call Mars the Red Planet, it’s really more pale orange than bright red. Even so, it really stands out from everything else.
Jupiter and Saturn are also in the evening sky at the moment, but they are quite low and set in the west quite early in the evening, whereas Mars will remain visible throughout the evening and night.
Because Mars is the next planet out from the Sun it takes over twice as long as Earth to orbit the Sun. So Earth only catches up with it every two years and two months.This means that it is in a different part of the sky each time we get close to it.
The time around close approach of a planet is known as opposition, because that’s when the planet is opposite the Sun in the sky. The date of opposition this year is 13 October. For more about oppositions, see below.
Mars is actually at its closest to Earth on 6 October, but on that date the planet isn’t at its highest in the sky until around 1 am – not a good time for family observing! So we have chosen the date of NAW to be when Mars is much higher in the sky in early evening, although not quite as close. In addition, during the Week the crescent Moon also comes into the sky, providing another object for people to observe. And on 17 November we have the annual Leonid meteors – shooting stars – which will help this to be a true week of astronomy! Find out more about all these things at our page on Also worth observing
At its closest this year Mars will be 62 million km (39 million miles) from Earth, and during NAW it has moved away somewhat to 81 million km (50 million miles). That is about 200 times farther away than the Moon. Even light takes 4½ minutes to travel this distance.
At the moment there is a rover on Mars, called Curiosity. If the operators on Earth send a command to Curiosity, to take a picture for example, it takes 4½ minutes for the command to get there, then another 4½ minutes for the picture to come back. Radio waves travel at the same speed as light. When Mars is at its most distant, it takes over 20 minutes for a one-way journey. If you saw the film ‘The Martian’, you may have noticed that communications between Earth and Mars took a long time to get a reply, for this reason.
In summer 2018 Mars was also at opposition but it was very low down in the sky as seen from the UK, in about the same part of the sky that Jupiter and Saturn are in now. This made it hard to see fine details on the planet, as we had to look through a thick slice of our unsteady atmosphere. This year it will be almost as close, but as it’s higher in the sky we will get a better view through our telescopes.
The turbulence of Earth’s atmosphere is what makes stars twinkle. However, Mars and the other planets rarely twinkle because they have discs, rather than being points of light like the stars. So that’s another distinguishing feature of Mars, as well as Jupiter and Saturn – it doesn’t twinkle.
You won’t really be able to see the disc of Mars through ordinary binoculars, as even at its closest it is quite small. However, if you can get hold of a telescope that magnifies about 40 times you should be able to glimpse the disc, although to see any details you need a magnification of 75 or more.
Usually during a National Astronomy Week there are stargazing evenings all around the country where you can look through telescopes, but this year the number of such events is very limited. But do go out and view Mars for yourself in the sky, and watch our livestreaming events to see what it looks like through a telescope.
You can find out more about looking at Mars through a telescope on our Observing Mars page.
Oppositions occur when a planet more distant than the Earth is exactly opposite the Sun in the sky as seen from Earth, so they are the time when the planet is closest to Earth in it orbit. Being opposit the Sun means that they are due south at midnight (as seen from the northern hemisphere, and are also best placed for observation.
In the case of Mars in particular, they are also the time when space missions to Mars are launched so as to have the shortest journey time. Or rather, the missions are launched about three months before opposition, then arrive about three months afterwards.
Look at the animation below to see how the Earth and Mars get close in their orbits in October 2020, then separate again, and why successive oppositions take place at different times of year and with different separations between the planets.
Below is an animation showing how the position of Mars in the sky changes over the years as a result of the movement of the two planets. Earth is represented by the blue dot in the middle. Mars is the pink dot. As it goes around the Sun in its orbit, it moves through the sky from right to left. However, around the time of opposition, the planet appears to go backwards in the sky (called a retrograde loop) because the Earth moves faster in its orbit than Mars.
Each successive opposition is represented by a separate loop. The different loop sizes are caused by the varying distances of Mars at each opposition, shown at the bottom.
Text by Robin Scagell
Last Updated: 2020-10-13 17:45:36