Venus is Earth's closest neighbor and is in many ways similar to our planet. Both belong to rocky planets, have almost the same size, mass and density. However, much about Venus is still unknown. Research is hampered by a dense blanket of highly reflective sulfuric acid clouds that hide the surface of Venus and the high temperatures capable of melting lead.
Astronomers from the University of California at Los Angeles reported their findings, which were the result of observations over 15 years, according to phys.org. From 2006 to 2020, scientists observed Venus from the Goldstone Observatory in the California Mojave Desert. As a result, the team determined the exact length of the day on Venus, the tilt of its axis, and the size of its core. The results of the study are published in the journal Nature Astronomy.
New radar measurements show that the average day on Venus lasts 243.0226 Earth days, that is, about two-thirds of the Earth's year. At the same time, the speed of rotation of Venus is constantly changing: neighboring days differ from each other by at least 20 minutes. Most likely, this explains the discrepancies in the previous calculations.
The dense atmosphere of Venus is to blame for this, which makes the planet either accelerate or slow down its rotation. On Earth, this effect also exists, but our atmosphere takes or adds no more than one millisecond per day. The atmospheric pressure on the surface of Venus is 93 times higher, so it affects the rotation speed much more strongly.
The angle of inclination of the Venus axis is –2.6392 degrees (near the Earth - about 23 degrees). The planet's core is about 3,500 kilometers across - almost like Earth's. But it is not yet known whether it is liquid or solid.