Jun 04, 2021 06:00:00

The long-standing mystery 'the length of a day on Venus' is revealed by 15 years of measurement

Venus has the closest orbit to the Earth in the solar system, and is also called the ' Twins of the Earth ' because it is close to the Earth in size and average density. The exact rotation period of Venus was revealed by a 15-year measurement by a research team at the University of California, Los Angeles (UCLA).

Spin state and moment of inertia of Venus | Nature Astronomy
https://www.nature.com/articles/s41550-021-01339-7

How long is a day on Venus? Scientists crack mysteries of our closest neighbor | UCLA

https://newsroom.ucla.edu/releases/cracking-the-mysteries-of-venus

Several studies have been conducted to determine the rotation period of Venus. However, the values derived from these studies differed from each other, and although a rough rotation period was derived, the exact value was not clear. UCLA's research team said, 'Venus is a sister planet of the Earth, but basic characteristics such as the rotation period have not been clarified. Based on the accuracy of Venus's rotation period known so far. If you try to land on Venus, the landing point can be off by up to 30km, 'he said, emphasizing the significance of finding an accurate rotation period for Venus.

The method used by the research team to measure the rotation period of Venus is as follows. First, radio waves are emitted from the Goldstone Deep Space Communication Facility located in the Mojave Desert , California, toward Venus.

The irradiated radio waves reach Venus over a few minutes, and Venus reflects the radio waves like a mirror ball.

Radio waves reflected from Venus are received at the Goldstone Deep Space Communication Facility and the Green Bank Observatory, West Virginia. Based on the difference in radio wave reception time at both points that occurs at this time, the rotation speed of Venus and the inclination of the earth's axis of Venus are calculated.

The research team performed the above measurements 21 times during the 15 years from 2006 to 2020 and found that the average rotation period of Venus is equivalent to 243.0226 days on Earth. Furthermore, it was said that the rotation speed of Venus was constantly changing, and sometimes the rotation period changed by about 20 minutes.

The research team speculates that 'Venus's rotation period fluctuates greatly because the atmosphere of Venus is much heavier than the Earth', and 'there is a deviation in the rotation period of Venus required in the research conducted so far.' It is thought that this was caused by the constant fluctuation of the rotation period of Venus. '

◆ Bonus
This study revealed the exact rotation period of Venus, but there are still many unclear points about Venus.

Meanwhile, on June 3, 2021, NASA will carry out two missions, 'DAVINCI + ' to measure the composition of Venus' atmosphere and 'VERITAS ' to investigate the geological characteristics of Venus, from 2028 to 2030. Announced that. About 500 million dollars (about 55 billion yen) will be invested in each mission, and expectations for detailed elucidation of Venus are rising.

NASA Selects 2 Missions to Study'Lost Habitable' World of Venus | NASA
https://www.nasa.gov/press-release/nasa-selects-2-missions-to-study-lost-habitable-world-of-venus