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Two dusty discoveries can disrupt our understanding of the inner solar system.
Mercury A recent study suggests that its ultra-tight orbit shares a large ring of roaming dust. And a cloud of asteroids not yet discovered has probably given rise to a similar halo in the vicinity of Venus, concludes another article.
"It's not every day that we discover something new in the internal solar system," said Marc Kuchner, co-author of the Venus and Astrophysicist Study at the Goddard Space Center NASA Flight in Greenbelt, Maryland, in a statement. "It's just in our neighborhood."
Related: Our solar system: a picture of the planets
A ring very close to the sun
Earth and Venus have collected dust rings in co-orbit, because the planets guided the particles with powerful gravitational tugs. The path of Mercury, however, has been thought to be free of such a feature.
"People thought that Mercury, unlike Earth or Venus, is too small and too close to the sun to capture a ring of dust," said Guillermo Stenborg, a solar scientist at the Naval Research Laboratory in Washington, DC. the same statement. "They expected that the solar wind and the magnetic forces of the sun would sweep away any excess dust in Mercury's orbit."
But Stenborg and his colleagues broke that expectation. The researchers analyzed the images captured by one of NASA's Solar and Earth Observatory (STEREO) satellites, both launched in orbit around the sun in 2006.
The researchers created a model based on these photos to "remove" the dust that could make it harder to understand the data collected by STEREO, NASA recently launched Parker solar probe and other sun jobs.
When they applied the model to STEREO imagery, astronomers saw the dust – much more than she would have anticipated.
"This was not an isolated thing," said co-author Russell Howard, also a specialist in solar energy at the Naval Research Laboratory, in the same statement. "All around the sun, regardless of the position of the probe, we could see the same 5% increase in brightness or density of dust, but there was something there, and that Is something that extends around the sun. "
The team calculated that the dust ring was about 15 million kilometers wide. The researchers reported their results last November to The astrophysical journal.
An asteroid population unknown?
The Mercury-orbit ring is a little smaller than the halo that shares the path of Venus, which, although barely 10 million km (6 million miles), extends over 26 million kilometers (16 million miles) from top to bottom.
But these rings of dust are extremely diffuse. For example, the co-orbital halo of Venus is only 10% denser than the surrounding space, NASA officials said in the same statement. And if you gather all the dust of this ring, you will get an asteroid of only 3.2 km.
In the second article, Kuchner and fellow astrophysicist Goddard, Petr Pokorný, sought to understand where the dust came from in the orbital ring of Venus. Scientists have modeled all potential dust sources they could think of – objects in the main belt of asteroids between Mars and Jupiter (the main source of Earth's co-orbit ring), Oort Cloud comets, comets of the Jupiter family, etc.
"But none of them worked," said Kuchner. "So we started to create our own sources of dust."
The simulations of the researchers helped identify the likely culprit: a population of unknown asteroids creeping around the sun in the trajectory of Venus.
"We thought we had discovered this population of asteroids, but then we had to prove it and show that it worked," said Pokorný, the lead author of the study, in the same statement. "We're excited, but then you realize:" Oh, there's so much work to do. "
The duo therefore built another model, which tracks 10,000 hypothetical asteroids from Venus in orbit through 4.5 billion years of solar system history. In the simulation, about 800 of these space rocks survived until today, suggesting that such a population might well exist in the orbital trajectory of the Earth's sister planet.
It would not be shocking for this small colony of asteroids to have escaped detection; for starters, no one had really looked for such rocks before. And it's hard to spot asteroids inside Earth's orbit, as they get lost in the blinding glare of the sun, the researchers said.
Nevertheless, if the asteroid population of Venus' neighborhood exists, "we should be able to find it," Pokorný said. NASA's Hubble Space Telescope could potentially do the job, he added.
Pokorný and Kuchner reported their findings in a study published online today (March 12) in The letters of the astrophysical journal.
Mike Wall's book on the search for extraterrestrial life, "Over there"(Grand Central Publishing, 2018, illustrated by Karl Tate), is out now. Follow him on Twitter @michaeldwall. Follow us on twitter @Spacedotcom or Facebook.
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