Get out and look up to the sky to see Mars. On July 31, 2018, Mars will be closer to, and therefore brighter, than it has been since 2003 and closer and brighter than it will be until 2035. It will be brighter than the brightest star of the night sky.
On July 27, the day of the lunar eclipse, Mars will be in Opposition. Oppositions occur when the Sun, Earth, and the planet in question (in this case Mars) are aligned. For our neighbor, this phenomenon occurs approximately every 2 years and 2 months. On this occasion, the distance between Earth and Mars will be slightly less than 58 million km , the smallest since the opposition that occurred in 2003, hence the red planet looks very bright during these weeks.
As we already know, that same night, near Mars, there will be a total lunar eclipse (the longest in the 21st century) visible for about half of the Earth (South America, Europe, Africa, Asia and Australia).
What is a Mars opposition?
The Mars Opposition occurs when Mars is on the opposite side of the Earth from the Sun.
How bright will Mars look?
Mars will be brighter than Jupiter, and almost 3 times brighter than the brightest star in the night sky, that is, Sirius. It will approach -2.8 magnitudes. The only brightest natural objects in the sky will be Venus, the Moon, and the Sun.
How far away will Mars be in this approach event?
At 57.7 million kilometers in the opposition and 57.6 million kilometers at its closest point of approach.
How big will it look?
In the closest approach to opposition this month, Mars will be 24.31 arc seconds in diameter. The apparent brightness of Mars will increase as it gets closer to Earth.
Will I be able to see the disk of Mars without help, by direct observation?
The angular resolution of the human eye is about 1 arc minute, which is 60 arc seconds, so the answer is … no. Mars will appear as a point of light for our eyes.
Will Mars appear as big as the full moon?
The full moon has an angular diameter of about half a degree or 1800 arc seconds. So, therefore, the moon will look approximately 74 times larger in diameter than the maximum size of the disk of Mars.
What will Mars look like through a telescope?
It depends on the telescope . Through a small telescope, we will see Mars as an orange / red disk. Through more powerful telescopes, the planet’s features may be visible, although with the current dust storm on Mars, we probably won’t be that lucky.
Why is it closer to Mars during some oppositions?
Mars is closer, and therefore appears brighter, as well as larger through a telescope, during some oppositions, mainly due to the elliptical (non-circular) orbit of Mars. If both Earth and Mars had circular orbits, then their minimum distance would be the same. But Mars, in particular, has a significantly elliptical orbit. So if Earth approaches Mars when Mars is closest to the Sun (perihelion), then Earth and Mars are significantly closer than during oppositions at aphelion.
2018 has a perihelic opposition: Mars is near perihelion. The next Mars opposition that will take place in 2020 will be further away, and the following ones even further. We will have to wait until 2035 to have an astronomical event of this approach again.
Reference: NASA
