How long is the longest day in the solar system? Venus Has the Answer By Reuters

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3/3 © Reuters. FILE PHOTO: The planet Venus is seen in this photograph taken by NASA’s Mariner 10 spacecraft 2/3

By Will Dunham WASHINGTON (Reuters) – Data obtained by bouncing radio waves off Venus, treating it, as one scientist put it, like a giant disco ball, provides a new perspective on Earth’s closest planetary neighbor, including a calculation precise length of Venus Day. The study also measured the tilt of Venus’s axis and the size of the planet’s core, allowing a deeper understanding of an enigmatic world sometimes called Earth’s “evil twin.” It was already known that Venus has the longest day, the time it takes for the planet to rotate on its axis, of any planet in our solar system, although there were discrepancies between previous estimates. The study found that a single Venusian rotation takes 243.0226 Earth days. That means a day lasts more than a year on Venus, making one complete orbit around the sun in 225 Earth days. Researchers transmitted radio waves to Venus 21 times between 2006 and 2020 from NASA’s Goldstone antenna in California‘s Mojave Desert and studied the radio echo, which provided information on certain planetary features, at Goldstone and at the Green Observatory. Bank in West Virginia. “Each individual measurement was obtained by treating Venus like a giant disco ball. We illuminated Venus with a giant flashlight, the radar at Goldstone, and observed the reflections as they swept across the Earth’s surface,” said UCLA professor of planetary astronomy Jean. – Luc Margot, who led the study published in the journal Nature Astronomy. “Venus is an amazing laboratory for understanding planet formation and evolution, and it’s just a stone’s throw away. There are likely billions of Venus-like planets in the galaxy,” added Margot. The new data showed that the planetary core of Venus is about 4,360 miles (7,000 km) in diameter, comparable to Earth’s core. Previous estimates of the core of Venus had been based on computer models rather than observational data. Its core is almost certainly made of iron and nickel, although it is not clear whether it is solid or molten, Margot said. Venus rotates on its axis almost vertically, which means that it has no discernible seasons, while Earth is more inclined. The study calculated the tilt of Venus at approximately 2.64 degrees. That of the Earth is about 23.5 degrees. Venus, the second planet from the sun, is similar in structure but slightly smaller than Earth, with a diameter of about 7,500 miles (12,000 km). Above its foreboding landscape is a thick, toxic atmosphere consisting mainly of carbon dioxide, with clouds of sulfuric acid droplets. With a runaway greenhouse effect, its surface temperature reaches 880 degrees Fahrenheit (471 degrees Celsius), hot enough to melt lead. Venus rotates from east to west, in the opposite direction to all the other planets in our solar system except Uranus. In another quirk, its day-night cycle, the time between sunrises rather than the length of a single axial spin, takes 117 Earth days because Venus rotates in the opposite direction to its orbital path around the sun. Venus has received less scientific attention than Mars, Earth’s other planetary neighbor, and other destinations in the solar system. “I don’t think Venus would be more difficult to understand than other planets if we had adequate data, but there is a deplorable paucity of data on Venus,” said Margot. “There have been no NASA missions to Venus in nearly 30 years and about a dozen NASA missions to Mars in this time interval,” Margot said, adding that new findings on how Venus rotates could help future landing attempts.