See Mars at its closest and biggest in over a decade

Artist's conception of Mars opposition. Note that the sizes and orbits are not to scale. Credit: NASA

Monday, May 30, 2016, 3:48 PM - A week ago, we watched as Earth, Mars and the Sun lined up in a special configuration known as Opposition. Now, on the night of May 30, the orbits of Earth and Mars will bring the two planets to their closest approach in over a decade!

Head outside tonight, under a clear, dark sky, and you'll be in for a treat. Mars, one of our solar system next-door neighbors, will be at its biggest and brightest since 2005.

The southern night sky on May 30. Credit: Stellarium/S. Sutherland

Look to the south-southeast, and a triangle of three bright points will be visible among the stars. The left-most point will be the ringed planet, Saturn. The bottom point will be the star Antares. The right-most point, which will have a noticeable orange/red colour, will be Mars.

Sky conditions will be very important in seeing all three. The above representation - a simulated view using the night-sky software Stellarium - shows an idealized view. With clear skies, from a position far from urban light pollution, and with either plenty of time for eyes to become dark-adapted, or using a long exposure shot, this will be the view, including seeing the Milky Way stretching from the southeast into the northern sky.

If viewing from inside or close to an urban centre, such as in the Greater Toronto Area, expect most of the stars and the Milky Way to be lost from view due to the glare of the city lights. Mars should still bright enough to be seen, however, even from heavily light-polluted areas.

If you are stuck indoors tonight, under cloudy or rainy skies, you will want to tune in to the Slooh Community Observatory's livestream of the event.

Watch from the embedded livestream above, or connect via Slooh's website, from 9-10 p.m. Eastern Time tonight, to share your own photos of Mars during the event, chat with other audience members and interact with the hosts, and personally control Slooh’s telescopes.

Closest in over a decade, but it gets even closer!

As Mars and Earth orbit around the Sun, the distance between the two planets lengthens and shortens. When the planets reach opposition - where both are on the same size of the Sun, and the positions of the Sun, Earth and Mars form a straight line - this is typically when we see Mars at its biggest and brightest, but not all oppositions are equal.

Earth's orbit around the Sun isn't a perfect circle, but its close - so close that it's difficult to see that its an ellipse just from look at it. The elliptical shape of Mars' orbit is much more obvious, however, and because oppositions come along every 26 months or so, they never really happen at the same time of year. Thus, Mars opposition migrates around Mars' orbit. The last time it was closer was over a decade ago, in November of 2005, when it was around 69 million kilometres away. Since then, the distance at opposition lengthened for the 2007, 2010 and 2012 events, and it has shortened since, for the 2014 and now this 2016 occurrence.

One catch though: due to the exact shape of Earth's and Mars' orbits, opposition doesn't always mark the exact time of closest approach. The timing of opposition and closest approach becomes closer when Mars is closer to perihelion (its closest point to the Sun) and aphelion (its farthest point from the Sun). When opposition happens somewhere in-between, however, the time between the two can stretch out to a week or more.

In this case, in 2016, the Sun, Earth and Mars lined up on May 22, but there has been a delay of around 8 days until the two reach their closest distance, at 75.3 million kilometres, on May 30.

Mars through a telescope, throughout 2016. Credit: NASA

This isn't the closest approach of Mars, though. If you happen to miss this one, due to your schedule or the weather, watch on July 31, 2018, when Earth and Mars will be 57.6 million kilometres apart - their closest since 2003, and closest until 2035.

Comparison between 2016 and 2018 views of Mars, as seen through a telescope, at closest approach. Credit: NASA

Sources: NASA | NASA | Online Astronomy Text