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Venus is Earth’s twisted twin in many ways, what about on the sky-watching side?
Sadly, stargazing is not great from the Venusian surface: the thick carbon dioxide atmosphere that covers the planet means there is no break in the clouds. But above those clouds – where, come to think of it, the conditions are less deadly for human astronomers anyway – the view of the night sky might be quite similar to that of Earth.
A sky observation session on Venus would require being, say, 35 to 40 miles (55 to 60 kilometers) above the surface, where the temperature and pressure are surprisingly similar to that of Earth, Paul Byrne, a planetologist at Earth, told Space. Washington University in St. Louis which focuses on Venus. com.
“This is the only other place in the solar system where ambient temperature and pressure conditions are present and, potentially, an astronaut could stand on the railing of a gondola with a breathing apparatus, but otherwise in shirt sleeves.” , did he declare. Maybe the stars would twinkle a little differently or the atmosphere would take on a tint meteors a different color, but the essentials would be the same, he predicts.
Related: Amazing photos of comet NEOWISE from Earth and space
Let’s stick to the meteor showers, because many sky observers have just lived this terrestrial experience, thanks to the superb Perseid meteor shower.
As long as you’re above the clouds, Byrne says, if the planet is swinging through the necessary debris, a meteor shower should work more or less the same on Venus as it does on Earth. “At this point and above, it would probably be similar to watching a sea level meteor shower on Earth,” he said. “I see no reason why you wouldn’t see shooting stars as things burn.”
The Perseids are caused by the Earth plowing a trail of dust deposited by Comet Swift-Tuttle. Comets are notoriously messy objects, the cosmic equivalent of Pig-Pen in the Peanuts comics, scattering dust wherever they go. And most meteor showers are caused by the same short-orbiting comet leaving a trail of debris along the path it takes, lap after lap through the solar system.
But there is a second, much rarer type of meteor shower that relies on a single pass of a long period comet, one that traverses the solar system for such a long path that the icy mass will never retrace its steps. over the course of a human life. More tricky could be an understatement: Earth watchers from the sky have never caught a meteor shower caused by fresh debris from a long-lived comet, at least not according to existing records. Theoretically, given that the two planets orbit the sun at similar distances, the same probabilities hold for Venus, despite the abysmal lack of records of observing the skies of this world.
But implausible doesn’t mean impossible, and if this scenario were to happen in our lifetime, the best chance of it happening could be in December.
Meet Comet Leonard
In December, Venus and a long-period comet called Comet C / 2021 A1 (Leonard) will almost cross each other, with the planet traversing the comet’s debris trail just three days after the frozen body rushed through Venus when it firsted. visit to the inner sun. system in some 80,000 years.
“There are a lot of unknowns here that could affect things a lot,” Qicheng Zhang, a planetary science graduate student at Caltech and lead author of a new paper exploring the scenario, told Space.com. “The odds are not particularly good for observing this event, but it is not impossible and it would not be completely surprising if something ends up being observed.”
Zhang is fascinated by comets for their brightness and unpredictability, which is why he checks a list of newly discovered comet candidates every day to see what scientists have spotted. In January, he came across an ad for Comet Leonard, which immediately marked him.
“I am interested in comets that pass quite close to the sunZhang said. . “So Zhang took a closer look at the comet. Leonard to see how its path aligned with the sun and the inner planets.
“The only thing that stood out is that the orbit of the comet and the orbit of Venus intersect almost perfectly,” said Zhang. Their orbits are less than 50,000 km, which is equivalent to the distance from Earth to the ring of geosynchronous satellites orbiting above our heads. The bodies themselves will be within 2.7 million miles (4.3 million km) of each other on December 18; the next day, Venus will cross the trail of the comet three days from the frozen body.
But Comet Leonard makes only one pass and hasn’t built such a clear path of debris, so Zhang wanted to determine if its rubble could be large enough to trigger a meteor shower on Venus at the December intersection. – and, if that, if there was a possibility that humans could somehow observe it.
The research is described in a paper posted July 26 on the arXiv.org preprint server and submitted to the Astronomical Journal.
A Venusian meteor shower?
According to calculations by Zhang and colleagues, the most promising scenario for an observable meteor shower as Venus crosses the comet’s trail would require high levels of activity on the frozen body when it was at least 30 times the average distance from the Earth to the sun (or roughly the distance of Neptune), perhaps closer to 100. It is not impossible, but it is rare, and it would mean that the comet Leonard was covered with particularly volatile ice, likely to transform into vapor in still rather freezing conditions .
For a spectacle spectacular enough for scientists on Earth to spot the fireworks on Venus, according to Zhang’s calculations, this activity should have started at a distance from the sun closer to 500 or even 1,000 times that of Earth. .
“It’s very far away, and long before the comet was discovered. We don’t know if the comet was actually active at that distance,” he said. “If we had a positive meteor detection on Venus from this event, it would tell us that this comet was quite active at a high distance from the sun.”
And not much about the oscillation of the comet through the solar system itself can improve the odds. “The only thing that could possibly change or add meteors to the rain from now on is if there were to be a highly explosive explosion of the type that very few comets in history have produced,” Zhang said. “It’s not something you would normally expect to see in a comet and it would be very unusual” – more unusual than spotting meteors on Venus, even.
This means that everything is unlikely, but still possible.
If Comet Leonard sets off a meteor shower that humans manage to observe, it wouldn’t be the first such data to come from beyond Earth.
In October 2014, a comet dubbed Siding Spring swept through Mars, the red planet plying the comet’s dust trail about three hours later. The meteors fell on the opposite side of Mars from Earth, but NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) the spacecraft picked up the ephemeral signature of the magnesium that the comet’s debris dumped into the upper atmosphere of the Red Planet.
Siding Spring’s encounter with Mars doesn’t make for an easy comparison to the potential December fireworks in Venus. Comet Leonard will never get as close to Venus as its predecessor did to Mars, and Venus is home to only one orbiter, the Japanese spacecraft Akatsuki, unlike the four orbiters and two rovers that were stationed on the red planet in 2014, according to NASA.
But the Earth, Venus, and the sun will be oriented in such a way that observers on Earth can pick up faint lightning from debris from Comet Leonard, Zhang noted, which was impossible when Comet Siding Spring met. “There has never been a chance to see a Martian meteor shower from Earth,” he said.
“Venus will be much closer to Earth than Mars was, and so it is possible that if there was something of interest,” – remarkably large meteors born from comet activity at enormous distances of the sun, for example – “which could potentially in theory be visible from Earth by quite small, even advanced amateur class telescopes,” he said. The Hubble Space Telescope will not be able to attempt observations because Venus will be too close in the sky to the sun at that time.)
And although Zhang doesn’t hold his breath for an awe-inspiring demonstration, if the encounter produces a spectacle, it could produce the same kind of metallic traces in Venus’ atmosphere that comet Siding Spring did in Venus. March.
“Our uncertainties cannot exclude that there may be a very large meteor storm, an impressive large meteor storm of the kind that would be needed to generate a meteor layer of the type that appeared on Mars,” Zhang said. . “It’s still a possibility, but a much smaller possibility than a very small meteor shower.”
Once in a lifetime
Chances are, neither Comet Leonard nor any other will have the same opportunity to make its mark on Venus in our lifetime.
Such close cometary overflights of the inner planets are unusual, Zhang noted. “This event probably recurs on the timescale of the order of once every few centuries or so per planet,” he said. “This is a fairly rare event, as far as close encounters of comets are concerned.”
And whatever happens to Venus, said Zhang, Comet Leonard is on its last pass through the solar system. The heat of the sun can tear the frozen body to pieces, a risk comets always take on their excursions.
If not, Zhang and his team calculated that the rest of the solar system would jostle the comet’s orbit enough that this time Comet Leonard would move away from our neighborhood and find itself stranded in interstellar space.
Email Meghan Bartels at [email protected] or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.
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