By Will Dunham
WASHINGTON (Reuters) – Data obtained by bouncing radio waves from Venus – treating what a scientist said, like a giant disco ball – provide new insights into Earth’s closest planetary neighbor, including an accurate calculation of the duration of a Venusian day.
The study also measured the inclination of the Venusian axis and the size of the planet’s core, enabling 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 the planet takes for a single rotation on its axis ̵
The study showed that a single Venusian rotation takes 243.0226 Earth days. This means that a day lasts longer than a year on Venus, making a complete orbit around the sun in 225 Earth days.
The scientists transmitted radio waves to Venus 21 times from 2006 to 2020 from NASA’s Goldstone antenna in the Mojave Desert, California, and studied the radio echo that provided information about certain planetary features at Goldstone and at the Green Bank Observatory in West Virginia.
“Every single 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 Earth,” said UCLA planetary astronomy professor Jean Luc Margot, who led the study. in the journal Nature Astronomy.
“Venus is an amazing laboratory for understanding planet formation and evolution, and it’s a stone’s throw away. There are probably billions of Venus-like planets in the galaxy,” Margot added.
The new data showed that the Venusian planetary core has a diameter of about 7,360 km (7,000 km) corresponding to the Earth’s core. Previous Venus core estimates were based on computer modeling rather than observational data.
Its core almost certainly consists of iron and nickel, although it is unclear whether it is solid or molten, Margot said.
Venus spins almost straight up on its axis – meaning it lacks distinct seasons – while Earth has more of a slope. The study calculated the Venusian slope of approx. 2.64 degrees. The Earth’s 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 approx. 7,500 miles (12,000 km). Above its preceding landscape is a thick and toxic atmosphere consisting primarily of carbon dioxide with clouds of sulfuric acid droplets. With a continuous greenhouse effect, the surface temperature reaches 880 degrees Fahrenheit (471 degrees Celsius), hot enough to melt lead.
Venus spins from east to west, the opposite direction from all other planets in our solar system except Uranus. In another distinctive feature, its day-night cycle – the time between sunrises as opposed to the length of a single axial spin – takes 117 Earth days because Venus rotates in the opposite direction of its orbit around the sun.
Venus has received less scientific attention than Mars, Earth’s other planetary neighbor, and other destinations in the solar system.
“I do not think Venus would be harder to understand than other planets if we had sufficient data, but there is a regrettable scarcity of data about Venus,” Margot said.
“There have been no NASA missions to Venus for nearly 30 years and about a dozen NASA missions to Mars in this time interval,” Margot said, adding that the new findings on how Venus spins could help any future landing attempt.
(Report by Will Dunham, edited by Rosalba O’Brien)