Mars close approach visible on December 8

Mars is closest to Earth at opposition, this is when the Earth passes between Mars and the Sun, and the views will be spectacular.

Even for those without a telescope, Mars will appear like a bright red star just above the full moon.

Views will be sharp if you've got a medium to large telescope, Adelaide Planetarium astronomy lecturer Paul Curnow said.

"Martian oppositions occur roughly every 780 days, and although the planet will still be over 80 million kilometres away, it's worth going out for a look," he said.

For those keen to catch a glimpse of the red planet, look towards the northeast (in the constellation Taurus), find the full moon, and Mars will be about four degrees above.

This is when Mars and Earth come nearest to each other in their orbits around the sun.

Close is a relative term, NASA says. The minimum distance from Earth to Mars is about 54.6 million kilometres. However, that doesn't happen very often.

"If Earth and Mars had perfectly circular orbits, their minimum distance would always be the same. However, they have elliptical (egg-shaped) paths," the space agency said.

Gravitational tugging means the two planets constantly change the shape of their orbits, with Jupiter influencing the orbit of Mars.

The orbits of Mars and Earth are also slightly tilted with respect to each other.

"All of these factors mean that not all close encounters are equal. In 2003, Mars made its closest approach to Earth in nearly 60,000 years! It won't be that close again until the year 2287," NASA said.

If the sun were as tall as a typical front door, Earth would be the size of a dime, and Mars would be about as big as an aspirin tablet.

Mars orbits our sun, a star. Mars is the fourth planet from the sun at an average distance of about 228 million kilometres.

One day on Mars takes a little over 24 hours. Mars makes a complete orbit around the Sun (a year in Martian time) in 687 Earth days.

Mars is a rocky planet. Its solid surface has been altered by volcanoes, impacts, winds, crustal movement and chemical reactions.

Mars has a thin atmosphere made up mostly of carbon dioxide (CO2), argon (Ar), nitrogen (N2), and a small amount of oxygen and water vapor.

Mars has two moons - Phobos and Deimos.

There are no rings around Mars.

Several missions have visited this planet, from flybys and orbiters to rovers on the surface. The first true Mars mission success was the Mariner 4 flyby in 1965.

At this time, Mars' surface cannot support life as we know it. Current missions are determining Mars' past and future potential for life.

Mars is known as the red planet because iron minerals in the Martian soil oxidize, or rust, causing the soil and atmosphere to look red.

The month March is name after Mars.

Roman war god Mars, they had a day named Mars day. "When the anglosaxons adopted the Martian war god, they applied their old English war god's name of Tiw (Tyr) to it the day and that's where we get Tuesday," Mr Curnow said.