WATCH: Mars passing its closest to Earth in 15 years

The Red Planet will appear super bright with its orange-red colour

WATCH: Mars passing its closest to Earth in 15 years

The distinctive Mars planet | Image: NASA

Mars, the fourth planet from the sun, is passing its closest to Earth in 15 years.

The Red Planet will be 35.8 million miles from us, making it a perfect opportunity to spot it in clear skies.

While 35.8 million miles is not what most of us would consider 'close', in planetary terms, close is relative.

On July 31st, Mars will appear super bright, and will be hard to miss with its orange-red colour.

From July 27th until the 30th, the point in Mars' orbit will come closest to Earth, and will be closest to Earth on Tuesday.

Mars will not get this close again until 2035.

What defines a 'close approach?' - The minimum distance from the Earth to Mars is about 33.9 million miles and does not happen very often.

Because Earth and Mars have elliptical orbits and are slightly tilted to each other, all close approaches are not equal.

When Mars approaches what astronomers call 'opposition', it and the Sun are on opposite sides of the Earth.

Earth and Mars align in opposition about every two years: this is why most NASA missions to the Red Planet are at least two years apart, to take advantage of the closer distance.

Image: NASA

Back in 2003, Mars was 34.6 million miles from Earth and the closest it had been in nearly 60,000 years.

This type of proximity will not happen again until 2287 - but there will be another close approach in October 2020.

NASA streamed the event live from the Griffith Observatory in Los Angeles.

David Moore is editor of Astronomy Ireland magazine: "In the 19th century telescope users thought that the dark markings they were seeing on Mars for the first time were evidence of vegetation, and some even thought that they saw thin lines that were canals built by intelligent Martians.

"So, it was close approaches in the 1800s that led to all the stories of 'little green men from Mars' and aliens being predominantly Martians.

"Mars will be closest today, July 31st, but it will be very close for many weeks meaning telescope owners can get superb close up views for a couple of months at least.

"Right now, Mars is at its highest in the South around 1.30am and looks like the brightest 'star' in the sky with a definite orange/red colour - I saw it this morning before dawn."