Scientists have discovered that Venus circles the sun embedded within a huge band of dust that is 10-15 million kilometres high and stretches all the way around its orbit. The finding will help astronomers better understand the dust clouds within planetary systems so that they can be taken into account when examining planets outside our solar system.
The inner solar system is filled with dust between the planets, called the zodiacal cloud, which starts out at the asteroid belt and slowly drifts towards the sun. “This cloud is a prominent feature when you look from one of these space cameras, you can see this cloud very clearly, but it looks like a very smooth cloud, we don’t see very much structure in it,” said Mark Jones, of the Open University. “What we’ve found is this ring near Venus which results from an interaction of that dust with the planets.”
The dust in the cloud normally takes around 100,000 years to travel from the asteroid belt to the sun, said Jones, but if any of it gets near Venus the particles can get trapped, by the gravity of the planet, inside its dust ring for a very long time. “It makes this sort of structure in the dust cloud, this ring that goes all the way around the sun,” Jones said. His findings are published on Thursday in the journal Science.
The dust in the ring is only fractionally – around 10% – more dense than the rest of the zodiacal cloud. The orbit of Venus around the sun is 220 million kilometres in diameter and the dust cloud resembles a huge wedding band around the star. “It’s too faint to see it from the surface of the Earth but if you could see it, it would stretch 45 degrees either side of the sun, it would fill half of the daytime sky,” Jones said.
Studying the dust ring will allow scientists to improve their ability to detect planets outside our solar system. To get the best resolution optical images of planets around other stars, astronomers need to take account of how the dust in those systems behaves. Any dust rings in other systems might give a signal that scientists might erroneously think is a planet. There are theoretical models of how to potentially take account of the dust but these need to be tested with experiments.
“You need to understand what these rings are doing in order to understand what these future exoplanet observations are like,” said Jones. “What this Venus ring will allow you to do is test some of those detailed models.”