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  • Writer's pictureLuke


Updated: Mar 12, 2021

In the eastern sky there is a bright distinctly red spot of light that comes out fairly quickly after sunset. I’m sure you’ve guessed already this is the planet Mars! This year Mars has been particularly bright red for a few reasons and is the brightest it will be for fifteen years!

The true color image of Planet Mars, shot by Rosetta in February 2007

Mars takes 2 years to go around the Sun where it takes the Earth 1 year. This means about every 3 years we catch up with mars and pass by it. When this happens it is called ‘opposition’. Opposition means an alignment of the Sun the Earth and one of the outer planets (outer planets are planets that are further from the Sun than us: Mars, Jupiter, Saturn, Uranus, Neptune). You can see when this happens by watching the sky at sunset, because the Sun, Earth and another planet is in alignment the planet is on the opposite side of the of the sky from the Sun. After you watch the Sun set in the west, turn around and see the planet that is in opposition rise in the east, for that night that planet will be as above the eastern horizon as the Sun is below the western horizon (the same phenomenon can be seen at full moon too). This will happened on October 13th 2020 for Mars. Because opposition is happening this year that means we are closer to mars then we will be for another ~3 years.

Mars will be in opposition on October 13th 2020.

To visualize why this makes Mars so much brighter lets talk about Astronomical Units. An Astronomical Unit (AU) isn't just hyperbole but actually a defined scientific unit that is useful for talking about distances within our solar system. 1 AU is defined as the distance from the Earth to the Sun. The distance from Mars to the Sun is 1.7 AU because mars is 70% further from the Sun than Earth is. Now to help visualize this let's shrink the solar system down to something we can manage if we shrink 1 AU to equal 10m (~10 yards) saying the Earth is ~10 yards away from the Sun (Earth would be about 1mm big at this scale, about the size of a grain of sand, The Sun is 110 times the diameter of earth so it would be 110mm about the size of a grapefruit) Mars would be 1.7 AU ~ =17 yards away from the Sun at this scale (Mars is about 1/2 the diameter of Earth so it would be .5mm at this scale, a small grain of sand). So now if Mars was lined up with Earth on the same side Mars would only be 7 yards away, but if Mars was on the opposite side of the Sun Mars would be 27 yards away from Earth. Something as small as a grain of sand would look a whole lot easier to look at if it was only 7 yards (.7AU) away rather than 27 yards (2.7AU) away. That's why years like this year where we are in "opposition" with Mars and on the same side of the Sun as Mars, it becomes much brighter and easier to see in the night sky.

In addition this year we are actually even closer to Mars than usual because both the Earth's and Mars's orbits are not perfect circles but slightly more like an oval meaning sometimes we are slightly closer or further from the Sun. It just so happens this year we are reaching opposition at the same time that both we are slightly further from the Sun than average and Mars is slightly closer to the Sun than average meaning the Earth will be even closer to Mars this year than it was last time we were in opposition. Actually we will be closer this year than we will for the next 15 years worth of oppositions. However I would mitigate expectations here by saying this will be much like the "supper Moon" where it's talked up as being a big deal but it's not exactly easy to tell the difference between the super moon and a normal moon.

NASA image showing comparison of a supermoon (left) and a micromoon (right)

Because we are so close to Mars Astronomers have been planning to do a lot of research on mars this year. You may have seen that this last July three probes were sent to Mars. One from the United States, one from the United Arab Emirates, and one from China. Because we are so much closer to mars this year it's cheaper to send the probes the shorter distance to Mars this year. The one from the US is NASA's Mars 2020 rover (it was named before we knew how much of a disaster 2020 was) and is set to land on mars on 2021 deploying the "Perseverance" rover and a helicopter drone named "Ingenuity" hopefully filling the hole left from when the Opportunity rover died in 2018.

(right) Ingenuity will scout for points of interest for the Perseverance rover to study.

(middle) Perseverance rover with seven scientific instruments labeled.

(left) The cruise stage will carry both spacecraft to Mars taking measurements along the way.

In 2018 there was a major dust storm on Mars which threatened the Opportunity rover by blocking out the sun so that the solar panels could not provide the power the rover needed to operate. The dust storm is well over now but NASA still hasn’t been able to contact the Opportunity rover. NASA suspects that dust has accumulated on rover's solar panels during the storm preventing them from charging the rover. This brought to an end a rover with over 14 years of operation, that had broke many records and made some amazing discoveries in that time. The Curiosity rover however has been operational this entire time as it relies on a nuclear power source which is also true for the Mars 2020 rover.

A penny the Curiosity rover uses to calibrate its camera. On the right is a photo from about a month after it landed and on the left is a picture 6 years from when it landed, just after the dust storm.

Setting in the south-west sky soon after sunset there is a star Anterries in the constellation Scorpio which is the red heart of the scorpion. I bring Anterries up as Anterries is Arabic and means ‘rival to mars’, this is because like mars it too is red. The rivalry comes when comparing the brightness between Mars and Anterries Mars is truly winning the rivalry currently but this is not always true. Actually usually Mars loses the rivalry 2 years out of 3 (when mars is further away, or on the other side of the Sun, as Anterries is always the same brightness). People will often come to me and point to Anterries or Aldebaran (a red star, currently below Mars and rising late in the night {~10:30p currently} that makes up the eye of Taurus the bull) or Betealgeuse (the red star you might be familiar with in Orion, currently appearing in our sky around midnight) and ask if it is mars and I have to tell them no… This year is different because we are passing so close to Mars, Mars is truly winning the rivalry and being the brightest red point in our night sky, you can't help but to point out as being Mars.

In a telescope or a good pair of binoculars mars appears as a red disk, where any of the red stars I mentioned will still be just a point of light. If you have a good telescope you might be able to see the white ice cap. With a really good telescope and a trick called occulting where you block out the light of mars you might be able to see mars's two faint moons Phobos and Deimos. Phobos and Deimos are small and irregularly shaped leading us to think they are most likely captured asteroids.

Mars in my best telescope.

Mars has captured our imaginations a lot through the ages starting with the Sumerians who likened it's red appearance to blood and saw it as an omen of war and blood shed. the Greeks and Romans went along with this naming it after their gods of war Aries and Mars (Marmor being an alternate name) respectively.

In modern times Mars is often the site of many scifi novels, movies, and art. This is owed in part to a wealthy and influential astronomer Percival Lowell who in 1906 claimed to see canals on mars that he thought were so straight they must of been engineered. Lowell wished to find life on mars so much that he started to. This hallucination was contagious and many other astronomers picked up on the canals. the story took off and inspired two generations of scifi writers and artist (Burroughs, Bradbury, Weinbaum, to name a few) who created works that went on to be inspirations for many artists to this day (Andy Weir, Kim Stanley Robinson, David Bowie and countless more). Lowell's observation was before photography when all astronomy was done by eye which leads many to say the canals were in the eye of the beholder, literally, as the drawings Lowel produced resemble retina of the human eye. We know now that there are no canals on mars but it wasn't until the Viking and Mariner probes of the 60s and 70s that hopes of canals on mars was finally put fully to rest.

Martian canals depicted by Percival Lowell.

Even without canals Mars is still an amazing place that captivates the imagination. Valles Marineris which is a system of naturally formed canyons that reaches 4 miles deep and would stretch across mainland United States if it was on earth. If human eyes ever see Valles Marineris up close I’m sure it will be a jaw dropping sight putting the grand canyon to shame. Mars is also home to Olympus Mons an extinct volcano reaching 72,000ft making it the largest mountain in our solar system (there is a case to be made for Rheasilvia a mountain on the asteroid Vela to be bigger). With science supporting the idea of frozen carbon dioxide (dry ice) snow storms, some have thought about skiing down Olympus Mons and getting lots of air with Mars’s low gravity (about a third of the gravitational force we have on earth). Along with volcanoes and canyons mars also has many impact craters that scar its surface. Mars is home to the greatest diversity of impact crater types of any planet in the Solar System.

Olympus Mons

Hope you enjoy observing Mars this evening. If you want to see it up close in my telescope I will be holding a tours through October.

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