October is the best month to observe Mars for 14 years

October is the best month to observe Mars for 14 years

October is the best month to observe Mars for 14 years

Mars will be the protagonist of the October skies. This weekend it is in conjunction with the Moon, also very bright because it has passed through the full moon on day 1. As the night progresses, the separation between the two stars will decrease and will be minimal at sunrise.

In successive days, its proximity, its orientation and its illumination, will make Mars be in optimal conditions for its observation, conditions that have not been that good for 14 years.

The red planet will appear in the sky in the east after sunset. It will reach its maximum elevation at about 45 degrees above the horizon, already at dawn, when it passes through the meridian. And it will continue on its way west to bed at dawn.

Day 6: maximum approach

Due to its characteristics, Mars can be considered as the little brother of the Earth: it is a rocky planet with an atmosphere and the length of the Martian day is similar to that of the Earth, but the diameter of the red planet is approximately half that of our planet.

October is the best month to observe Mars for 14 years

Right now, as these days go by, Mars is progressively approaching Earth. On the 6th it will be only 62 million kilometers away. Its proximity and the almost frontal illumination by sunlight make its beautiful reddish-orange glow already surpass that of the giant Jupiter, which is also observable on these nights, west of Mars.

Day 13: opposition

On Tuesday the 13th, the Sun, Earth and Mars will be perfectly aligned. Viewed from Earth, Mars will appear in a position completely opposite to that of the Sun. That is why we astronomers simply say that it is in 'opposition'. The days around the opposition are undoubtedly the most favorable for observing the red planet, since the lighting is then completely frontal: the entire Martian disk is lit by sunlight.

Mars is located 1.5 times farther from the Sun than Earth and it takes 1.88 times longer than our planet to complete one round of the Sun. As a consequence of all this, the Mars oppositions occur every 2 years and 47 days. During the last competition, which took place on July 27, 2018, we also enjoyed a beautiful total lunar eclipse. It was a sensational show. The next opposition will take place on December 8, 2022.

Not all Martian oppositions are identical, since the orbit of Mars is more elliptical than that of Earth. This makes the distance between the two planets vary slightly from one opposition to another. In 2018, Mars was 57.6 million kilometers away, while this year, as we have said, Mars will be further away, about 62.2 million kilometers on the 13th.

However, in July 2018 Mars remained relatively low above the horizon and the lower layers of the atmosphere, more turbulent, were in the way of observation. This year, Mars culminates at a much higher elevation, at about 50 degrees as seen from the Peninsula, the atmosphere will not disturb so much and the conditions for its observation will be much better.

To see the Martian surface

With the naked eye, the brightness of Mars will be splendid, but to observe the details of its surface it is necessary to use a telescope of at least 100x magnification . Even with the telescope, the image still looks small, and the whitish polar caps, for example, are very difficult to see. However, it is possible to see the large dark patches called 'seas', vast sandy plains where iron oxide abounds. As with our blood, it is iron that provides the characteristic reddish color to these plains.

Mars rotates on itself every 24 hours and 37 minutes. Therefore, the face that it offers us depends on the moment chosen. During the 2018 opposition, sandstorms left the surface of Mars completely screened for weeks. Fortunately, the weather forecasts for the red planet are much more favorable this year as no major storms are expected.


Rafael Bachiller is director of the National Astronomical Observatory (National Geographic Institute) and academic of the Royal Academy of Doctors of Spain.

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