Although the Mars opposition and closest approach were in late July, the planet still looks spectacular and will remain brighter than Jupiter for all of August. To the eye, a brilliant orange colour, it continues to look as if it shouldn’t be there! Indeed it hasn’t looked this bright since 2003.
Unfortunate for telescope viewing has been the persistence of an enormous planet-encircling dust storm which has obscured the surface features.
But the good news is that the dust is finally starting to settle!
Over the last week or so, more dust has been falling out of the planet’s thin air than has been rising with the dust raising occurring in ever smaller areas and in other areas stopping altogether. Some Martian landforms previously hidden have now become visible from orbit again.
This, along with the fact that Mars is rising a little higher in the sky night by night, should make the planet a very worthwhile telescope target for some weeks yet. Jupiter with its moons, and Saturn with its ring system will stay in prime observing positions also.
IMAGE LEFT: The red planet before and during its monster storm. Credit: JPL/NASA. See more here.
IMAGE RIGHT: A series of simulated images shows how conditions changed around NASA’s Mars rover, Opportunity, as the huge dust storm intensified throughout June 2018. At left, the Sun appears blindingly bright but darkens as the dust storm intensifies. At the far right, the Sun is a mere pinprick, with the dust storm in full swing. Credit: NASA/JPL-Caltech/TAMU
Can we even begin to imagine a dust storm of global scale?
Such monsters are not unheard of on the red planet. On average, they come to life once every three Mars years (about 5.5 Earth years), and they almost completely obscure the surface.
They put enough dust in the air to completely block out the Sun, but in doing so, they ultimately doom themselves. The radiative heat of sunlight reaching the surface of the planet is what drives these dust storms.
As sunlight hits the ground, it warms the air closest to the surface, which then rises taking the dust with it. These rising plumes of air create everything from dust devils to ‘small’ storms that occur about once a year covering a few million square kilometres and lasting several weeks. Typically, these happen during summer in Mars’ southern hemisphere. Sometimes these bad-boys morph into the great planet-encircling storms such as is being experienced right now. In this storm, only the 25 km high peak of Olympus Mons, the largest volcano in the Solar System, has remained proud of the obscuring dust.
Although they enshroud the planet, and block the light of the Sun, these storms are not as brutally fierce as we might imagine.
The winds on Mars top out at about 100 km/h and its atmosphere is only about 1% as dense as Earth’s. If you wanted to fly a kite on Mars the wind would need to blow a lot faster than on Earth. So, while things get blown on Mars, it is not with the same intensity. Also, because the air is so thin, the dust being suspended is very fine, something akin to the consistency of talcum powder.
Scientists have been tracking these monsters since 1909 using both Earth-bound telescopes and spacecraft orbiting Mars. The last storm of global magnitude that enveloped Mars was in 2007, making the current storm long overdue and long awaited for.
NASA’s Opportunity rover, being powered by sunlight, was forced to suspend science operations. However, the nuclear-powered Curiosity rover which made landfall five years AFTER the previous storm has been able to continue operating. Curiosity, along with a fleet of orbiting spacecraft, opens an unprecedented window to answer some questions, such as: Why do some Martian dust storms last for months and grow massive, while others stay small and last only a week? Why do the years’ long gaps between storms exist?
ABOVE: A dust devil. Early precursor to a storm? Credit: NASA
FRONT TILE IMAGE: The storm rolls in near the north polar ice cap. Credit: ESA
Opposition Open Night
On Friday, the night of Mars opposition, Stardome hosted an open night with over 2000 people through the doors, despite the less than favourable weather. We had six courtyard telescopes out as well as the large, historic Zeiss telescope open, and there were long queues at both. Volunteers informed visitors of the dust storms blocking out much of Mars’ details, so while some visitors were slightly underwhelmed of the view of Mars, many were very excited to simply get a peek through the telescopes at the red planet (and it’s stunning neighbours)!