Remember to see Mars! It is the biggest and brightest. If you miss it, you will have to wait for 10 years!

Have you noticed in recent days that there is a bright red star shining in the eastern sky in the first half of the night?

That's Mars .

As long as the weather is fine, you can't miss it if you look up at night. You can even take a picture of it with most mobile phones .

Mars was also very bright last night. I took this photo with my phone. | ​​Photo by Heijio Meimei

Mars opposition

Why is Mars so bright now? Because it is about to reach opposition again.

When Mars is in opposition, there are two major characteristics:

1. It is closest to us and appears to be the largest;

2. When viewed from our Earth, it is facing the Sun. Not only is its entirety illuminated, but it can also reflect sunlight more strongly into our eyes.

During opposition, Mars is closer to Earth and appears larger and brighter | EasyNight

Mars and Earth are like two athletes on a track, running around the sun in the middle along two adjacent tracks. Earth runs the inner circle, with good stamina and fast speed, and a short track, so it only takes a little over 365 days to complete a circle; Mars runs the outer circle, with poor stamina and slow speed, but the track is even longer, so it takes 687 days to complete a circle.

Therefore, in such a seemingly unfair arena, even if the Earth and Mars are initially at the same starting line, the Earth on the inner track will gradually overtake Mars on the outer track, leaving it farther and farther behind, until it is a full circle beyond it, overtaking from behind and "circling" Mars again .

On average, the Earth will overtake Mars once every 780 days, or about 26 months. At this time, the Earth and Mars have a chance to get close. From a third-party perspective, the Sun, Earth, and Mars will be roughly aligned at this time .

In astronomy, this phenomenon is called Mars opposition .

Martian onion? No, it's the Mars opposition! | EasyNight

This year, Mars opposition will occur on December 8.

No matter where you are, Mars will be visible all night long. In the evening, when the sun sets in the west, it rises in the east; when it gets dark, it will be shining low in the east. For the rest of the night, Mars will hang high in the south, slowly moving westward. In the first half of the night, it will be almost due east, then move to due south at midnight, and then to due west. It will not set in the west until dawn, when the sun is about to rise in the east.

Not a big rush, but better than a big rush

Mars opposition to the Sun is not always the same, but varies in size .

In a track and field stadium on Earth, the inner and outer circles of the track have different circumferences, but at least they are similar in shape and parallel to each other. When two athletes chase each other along the track, no matter where they pass each other, the distance between them is not much different.

But on the track and field of the solar system, the situation is different - although each track is an ellipse, its shape may be very different, and the direction of the major axis is also different.

The inner track where the Earth is located is about 150 million kilometers away from the Sun, with a difference of only 5 million kilometers between the closest and farthest points, which can be said to be nearly circular. The outer track where Mars is located is more than 250 million kilometers away from the Sun at its farthest point, but only a little over 200 million kilometers at its closest point, which is an obviously elongated ellipse.

This year's Mars opposition position on the "runway" | EasyNight

On these two "irregular" runways, every time the Earth overtakes Mars from the inner circle, it will catch up with a different position on the runway, resulting in a large difference in the closest distance between the two .

If Mars happens to be at its farthest point from the Sun, then during opposition, Mars will be 100 million kilometers away. On the other hand, if Mars happens to be closer to the Sun, it may be less than 60 million kilometers away from us during opposition.

This closest opposition only occurs once every 15 to 17 years, and we call it the "big opposition" ; the other oppositions are called small oppositions or ordinary oppositions.

Four years ago in 2018, we had a major opposition of Mars, when Mars was only 57 million kilometers away from Earth. The next major opposition of Mars will not occur until September 2035.

Mars appears to be getting bigger as opposition approaches | Jonathan T. Grayson

Mars: I want to fly higher!

This year's Mars opposition is not a "great opposition" and is much farther away from the Earth than a great opposition - the closest distance is about 81.5 million kilometers.

After this time, Mars will be farther and farther away from the Sun, until it reaches 100 million kilometers in 2027, and then it will start to approach the Earth again. It will not be until the opposition of Mars in 2033 that Mars will be closer to us than it is now.

So, it is still a great opportunity to appreciate Mars recently. If you miss it, it will not be closer or brighter in the next 10 years !

The distance between Mars and Earth is now the closest it will be in the next 10 years | EasyNight

Moreover, for those of us in the Northern Hemisphere, this year is more suitable for observing Mars than the Mars opposition in 2018 .

The orbits of the Earth and Mars are relatively fixed, and each Mars opposition occurs around August to September in late summer and early autumn. We know that the sun is very high at noon in summer, which means that Mars, which is opposite the sun during opposition, will be very low at midnight.

The 2018 Mars opposition is in August. Although it is closer to us than this year, from the northern hemisphere it always hovers low in the south, affected by haze, extinction and atmospheric disturbances, and it is not clear at all.

This year is different. Mars opposition occurs on December 8, which is already past the Great Snow solar term and not far from the winter solstice. Although it is freezing cold, the sun is low at noon, so Mars can rise very high at midnight , even close to overhead.

The higher it rises, the more enjoyable it is to watch!

Mars is in a better position for the Northern Hemisphere this year | EasyNight

Mars is visible to the naked eye

Although December 8 is the exact day when Mars will be at opposition, the month before and after is the best period for observing Mars .

For example, in recent days, the brightness of Mars has been comparable to that of Jupiter. The two are shining in the evening sky, one in the east and one in the west, one red and one white.

Around opposition, the brightness of Mars will reach its peak. In the words of astronomers, its brightness will reach -1.8 magnitude. Translated into plain language, Mars is now extremely bright , more than twice as bright as Vega, the brightest star in the summer night sky. If you don't know, if you accidentally see Mars, you might mistake it for a street lamp in the distance!

In 2018, Mars will be in opposition, and it will be in Capricorn. All the stars in this constellation combined cannot match the dazzling light of Mars, as if the stars have surrendered to the brightest red in the night sky | Yao Shun & Night Sky China

If you look at it with your naked eyes, the most striking feature of Mars these days, besides being extremely bright, is that it is red !

Mars itself appears rusty red due to the large amount of iron oxides on its surface. However, Mars is usually far away from us and the brightness is insufficient to stimulate the color-sensitive cones in our eyes, making it difficult to see the colors. During the opposition period, the brightness is not a problem at all, and Mars will be very conspicuously red .

If you take photos of Mars with your phone, the redness may not be obvious. If you are not content with this, you can use a camera, tripod, equatorial mount and other equipment to challenge more advanced photography.

The red Mars captured by the camera, yes, it is the brightest one! Shooting method: Nikon D810A + Sigma 40Art, ISO 1600, f/4, single exposure 120 seconds, night sky part equatorial tracking, landscape equatorial mount off, 2*2 stitching of sky and earth. | Pu Shi & Night Sky China

Mars is closest to Earth during opposition, which means it looks particularly large. On December 1, Mars will be closest to Earth , and in astronomers' terms, its apparent diameter will be 17 arc seconds. Translated into plain language, Mars will look 1/105 the size of a full moon! (Don't laugh, that's pretty big...)

Mars opposition and closest distance may be delayed by several days | EasyNight

Although it still sounds small, so small that it is just a point of light to the naked eye, with the help of a not-too-expensive telescope, if you magnify Mars 105 times, it will look as big as the moon! In most cases, to make Mars as big as the moon, you often need to magnify it more than 200 times. This is not something that can be done by just using a larger, more expensive, and more advanced telescope. It also requires the cooperation of an extreme environment to achieve it.

Now you can probably understand why opposition is a great time to observe Mars from Earth. Because the larger Mars appears, the more details we can easily see.

In fact, there are indeed many features on Mars that astronomers discovered during opposition, such as the two small satellites of Mars, dark patterns on Mars that resemble water channels (they were once mistaken for Martian "canals"), etc. With a telescope with higher resolution, you can even see the highest mountain in the solar system, Olympus Mons, and the largest canyon in the solar system, Valles Marineris!

On November 21, the photographer took a photo of Mars from Earth, with clear details | Damian Peach

Compared with the 2018 Mars opposition, this Mars opposition has another unique advantage: the air quality has improved! The air quality here does not refer to the Earth, but to Mars.

In the summer of 2018, a huge dust storm blew up on Mars, which soon swept across the globe and lasted for several months. During that time, if you looked at Mars through a telescope, you could only see a plain red marble. Even the white polar caps at the north and south poles were blurred, not to mention the dark lines and volcanoes, which were almost completely obscured by the dust storm. The dust storm even suffocated the famous Opportunity Mars rover. It lost contact with the Earth in June 2018, and NASA was forced to announce the end of the Opportunity mission in 2019.

This year, there are no dust storms on Mars , so the air quality is much better, and all kinds of landforms can be clearly shown in the telescope. I missed the good opportunity of the last Mars opposition, so I must seize the opportunity to see Mars this time!

You can see all these features on Mars if your telescope is big enough! | Ade Ashford

As far as observing Mars is concerned, the good time will continue for a while. At least until the end of the month, the Earth, which has overtaken Mars from the inner circle, will not have time to run too far away, and the brightness will remain above -1 magnitude. During this period, Mars will appear in the east every night, gradually move to the high sky in the south, and shine with a bright red light.

On a clear night you can't ignore it.

This year, when we look at Mars, we have an extra concern. The Zhurong rover is still on the surface of Mars and is about to end its hibernation , and the Tianwen-1 orbiter is still orbiting Mars. Although we cannot see them with the naked eye, we can also wish Mars all the best while we watch it!

Cute selfie of Zhurong｜CNSA / China Planetary Exploration

Author: EasyNight

Editor: Steed

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