How long is a day on Venus? The duration of each day is inconsistent

Venus is our sister planet, but its basic properties are still unknown. How long a Day lasts on Venus has long been a mystery, but new research suggests that the difficulty in unraveling the mystery comes not from a lack of surveying technology, but from the changing speed of the planet’s rotation.
Venus’s thick atmosphere makes it difficult for scientists to “see through it.”
Scientists have used a huge radar system to reflect Venusian light for more than a decade, so researchers have been able to measure the tilt of Venus’s axis, the size of its core, and how long it takes for the planet to complete a full rotation.
To solve the mystery of Venus’ daily duration, researchers used two powerful radar instruments: NASA’s Goldstone antenna and the Green Bank Observatory’s main dish antenna. Between 2006 and 2020, they used the radar system to reflect a beam of signals from the Goldstone antenna to Venus. They then studied the signals back to the Goldstone antenna and the Green Bank Observatory. They compared the time it took each site to receive the echoes and found that the interval was about 20 seconds.
This technique is analogous to shining light at a mirror ball. We think of Venus as a giant disco ball of light, and then we illuminate Venus with a very powerful flashlight — it’s 100,000 times brighter than a normal flashlight, and if we track the reflection of the disco ball, we can infer its rotating properties.
The researchers used the radar system to observe Venus 121 times, but because the technique is cumbersome and requires both devices to be in perfect condition, it took 21 attempts to collect useful data.
By analyzing the treasure trove of observations, scientists were able to calculate the precise tilt of Venus’s rotation — 2.6392 degrees, compared with 23 degrees for Earth. The analysis also revealed that the core is about 7,000 kilometers in diameter, or 58 percent of Venus’s diameter, but scientists say the calculation is still uncertain.
On the other hand, scientists need to make precise calculations about the length of Venus’s day, and the team’s results explain why previous analyses don’t match. The average duration of a Venusian day is 243.0226 earth days, but the rotation of Venus can vary by up to 20 minutes as it transitions from one Venusian day to another.
This may explain why previous estimates for each Venusian day were inconsistent. Researchers believe that this change is made up of Venus is thick, fast moving, the atmosphere caused by gravity, the earth’s atmosphere will affect the earth’s rotation, but because of the earth’s atmosphere than thin clouds of Venus, deviation in milliseconds between each rotation, more dense atmosphere of Venus, it around the slowly rotating planet only four earth day, This strange phenomenon has scientists baffled, but it could be affecting Venus’s rotation rate.
But if humans are planning more Venus exploration missions, we’ll need to address this problem. Without these measurements, we’re basically flying blind.