Wednesday, 7 December 2016

Trees on Mars

At the men’s breakfast at St Brelade’s Church, I was told, quite categorically, that there were trees on Mars. It was during a discussion of my forthcoming Astronomy Quiz night which I had just finished. So I wondered where this story came from, and why it was believed so readily.

According to the Daily Express "Alien believers shockingly claim that NASA is trying to cover up the existence of the 'trees' with an elaborate cover story for what they really are. This is under a story in March 2016 with the headline: "TREES FOUND ON MARS: Extraordinary image 'shows towering plants on the Red Planet'"

But would NASA really publish the photo in the public domain if they were trying to cover it up? And when they are searching for evidence of past life on Mars, why on earth wouldn't they shout this from the rooftops if it really was trees?
The image in question is of a vast region of sand dunes at high northern latitudes on Mars. And it is an old photo. The pictures have been on NASA’s site since 7th April 2008. They were taken via the HiRISE camera on the Mars Reconnaissance Orbiter.

NASA's Candy Hansen, writing for the Space Fellowship website in 2010, noted:

“There is a vast region of sand dunes at high northern latitudes on Mars. In the winter, a layer of carbon dioxide ice covers the dunes, and in the spring as the sun warms the ice it evaporates. This is a very active process, and sand dislodged from the crests of the dunes cascades down, forming dark streaks. In this image falling material has kicked up a small cloud of dust. The color of the ice surrounding adjacent streaks of material suggests that dust has settled on the ice at the bottom after similar events.”

And a commentator on the Universe Today added in 2010:

"Definitely not trees. At first glance, I can understand how you’d get that impression, though. But look closer. They “grow” in multiple directions, but they don’t cast shadows. Looking a little closer, they show as gullies carved in the faces of the steep sides of dunes."

It is an example of Pareidolia. That is the imagined perception of a pattern (or meaning) where it does not actually exist, as in considering the moon to have human features. It is something which we, as human beings, are very good it. It is an inbuilt way of seeing the world. But it can misfire, and we see (based on our experience) something which isn't really there.

Sometimes it can be used with good effect. For instance, the Horsehead Nebula is so called because it resembles a chess piece, so it is an easy way of making a quick and memorable identification: But no one ever believed there really was a giant chess piece hanging in space!

But often it can lead the casual observer astray. This site looks at all the photos which have been misinterpreted in this way.

One of the most notable is that seen in 1976. A photograph of a rock formation on Mars beamed to Earth by NASA?s Viking 1 orbiter looked to many like a face carved in the Martian surface. The Face on Mars photo?s legacy has survived to this day, even after additional observations by more advanced spacecraft have revealed it to be a trick of light and shadows.

So why did the tabloids run with this article?

It sells papers, even if they do give the more mundane explanation. Which would you prefer, a scientific explanation, or something which tells you about conspiracies to cover up the possibility of alien life? The latter always sounds exciting, hence the popularity of Dan Brown. An explanation which tells us there is alien life on another planet is so much better than one which exposes our own vulnerability to mistakes of perception. We want to see the Happy Face on Mars as a construct not an illusion.

1 comment:

James said...

The five words according to the Daily Express normally suffice to tell you that what follows is garbage...