MYSTERIES OF THE UNIVERSE
WHY IS MARS CONTINUING TO WOBBLE?
Researchers confirm that the Red Planet is spinning off its axis
Reported by David Crookes
© Alamy; Getty
Grab your telescope and gaze at Mars.Are you able to spot something unusual as you focus in on the planet, paying particular attention to its white caps? Not even a little bit? Here’s a clue: we’re referring to a teeny, tiny wobble that occurs as the poles wander from the Red Planet’s axis of rotation. Still can’t see it? Don’t worry – it’s taken scientists decades to spot some rather odd behaviour on the Red Planet.
For the past 18 years, radio tracking observations determined from satellites orbiting the planet have been able to show stark evidence of the Chandler wobble on Mars –a variation of latitude named after American astronomer Seth Carlo Chandler, who discovered the phenomenon in 1891. In simple terms, it means the Red Planet is repeatedly wobbling as it spins, in this case by just ten centimetres (four inches) from the planet’s axis of rotation – that’s why you’re unlikely to see it for yourself. If you’re after a nailed-on explanation of why it’s continuing to happen, then you’re sadly out of luck.
Although scientists have made a breakthrough in determining that the Red Planet wobbles in its rotation, they are not exactly sure what is driving it. What they’ve gleaned from studying the data so far is that the Chandler wobble on Mars occurs in a near-circular, counterclockwise direction, as viewed from its north pole, every 207 days. As a result, the poles don’t always line up perfectly. The Red Planet is the only other body in the universe known to exhibit such behaviour, with the phenomenon only ever discovered and confirmed on Earth before.
It makes the new discovery highly significant, and not just because there are now two planets resembling a spinning top teetering as it loses speed. This latest study shows the sheer importance of gathering and analysing information over a long period of time –a laborious process requiring heaps of patience, but one that has proven ultimately rewarding. “With 18 years of data, the Chandler wobble signal is very clear,” explains Alex Konopliv, an aerospace engineer at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. And as more data comes through, the better the conclusions will become.
Before we take a closer look at the Chandler wobble on Mars, let’s first briefly examine its effect on Earth by way of comparison. We know that our planet rotates on its axis every 24 hours – every 23 hours, 56 minutes and four seconds, to be exact – but while you may excitedly spin a globe on your desk and smoothly reach a destination when it comes to a halt, real life isn’t quite like that.