This weekend brings a spectacular cosmic show for stargazers, who will be able to see Mars, with or without a telescope, as it makes its way to its closest distance from Earth in more than a decade.
Early Sunday morning, Mars, the next planet out from the sun after Earth, reached “opposition” with Earth, which means it aligned in a straight line with our planet and the sun on its path in a wide, elliptical orbit about the sun. This weekend, and over the next few weeks, is the best time to see Mars, which will appear bigger and brighter in the night sky.
During opposition, Mars and the sun flank Earth on opposite sides, so the Red Planet will appear to Earthlings to rise in the East just as the sun sets in the West, making the sun-facing side of the orange-reddish planet luminous all night long.
There will be a rare chance on May 30 at 6 p.m. EDT (22:00 GMT) to view the planet at its closest point to Earth since November 2005, when it will be 46.7 million miles away.
Besides offering rare close-up views of Mars, opposition events are also a boost for space agencies such as NASA, which time the launch of rovers and orbiters to Mars around oppositions, as National Geographic points out, as the proximity of the planets saves money on fuel and time on travel.
Given its further distance from the sun and the different forces of gravity influencing it, Mars orbits the sun much more slowly and on a different plane than does Earth. For this reason it reaches opposition only once every 26 months, when it happens to briefly sync up with Earth’s tighter orbit around the sun.
The shape of Mars’s path around the sun is also more elliptical than Earth’s – and actually elongating over the centuries – so the distance between the two planets changes. This means that some oppositions bring the worlds closer together than others.
As NASA points out, this is because an opposition can happen anywhere along Mars's orbit. When it happens while the Red Planet is closest to the sun, which is called "perihelic opposition," Mars is especially close to Earth.
The last close encounter of this type was in August 2003, when Mars was 35 million miles from Earth, the closest the two planets had been in almost 60,000 years. Unfortunately for today’s stargazers, this won’t happen again until 2287.
Here is advice from Space.com on where in the sky to look for Mars during this month’s opposition:
The exact time when Mars will be above the horizon depends on your location. For example, in New York, Mars rises in the East at 8:10 p.m. EDT and sets in the West at 5:35 a.m. EDT, so it is above the horizon for 9 hours and 25 minutes. Farther south, it will be visible longer, and farther north, for a shorter time.
The easiest way to spot Mars this weekend is to go out when the Red Planet is highest in the sky, close to midnight local time. Remember that if you live in a part of the world that is on daylight saving time, that "sweet spot" of viewing times will be close to 1 a.m. your local time.
If you live anywhere north of the equator, Mars will be due south at midnight local time. If you live south of the equator, Mars will be high overhead.