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Venus. Image: NASA.
Typically, fresh news about exoplanets often comes with details about surface temperatures and the duration of a year for that planet. This has led many to wonder why we don’t know how long a year on Venus is, even though it’s the closest planet to us if we consider the Sun as the center. Recently, scientists at the University of California in Los Angeles, USA, have provided an answer to this question.
On Earth, we consider a year as a measurement of time, but in reality, it’s also related to speed and distance, calculating how long a planet takes to complete an orbit around its star. However, an Earth year isn’t exactly 365 days. We define a year as 365 days for convenience and add leap years to adjust everything accurately; otherwise, seasons would gradually slow down. On the other hand, a day is measured as one full rotation of a planet around itself. For scientists studying Venus, this has been a puzzling matter.
Numerous factors have complicated the study of Venus for scientists. For example, this planet rotates incredibly slowly, so slow that it hasn’t completed one full rotation before it moves too far for us to observe. Additionally, Venus is covered by thick clouds that make it even more challenging to observe its surface from Earth. Therefore, setting a landmark to track a day on Venus is impossible.
Consequently, to accurately calculate the duration of a day on Venus, researchers have spent more than ten Earth years observing it using radar, and they’ve discovered that while Venus has an “average day,” specific days are extremely difficult to predict. The uneven distribution of its mass within its spherical shape and its thick atmospheric layer are factors causing Venus to rotate either faster or slower. The relatively calculated result by the research team is that an average day on Venus lasts 243 Earth days. Yes, a day on Venus is about 2/3 of an Earth year.
What’s even more surprising about this discovery is that we previously knew how long a year on Venus was. Astronomers had calculated a Venus year to be 225 Earth days, which means a Venus year is shorter than its day. This is truly perplexing!
This study will assist scientists in planning more accurately for future missions to Venus. Inaccurate calculations based on outdated data could lead to serious issues for devices needing to land at precise locations on Venus. A better understanding of the planet’s motion will help minimize potential problems and risks.