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How Long Is a Day on Venus? How Long Is a Year?

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partial view of Planet Venus

You’d think that the Earth and Venus would have a lot in common, seeing as the two are the so-called sister planets. They’re not too different in size or circumference. Yet the 26,444,601 miles separating the two accounts for many things that make them worlds apart, including the lengths of their respective days and years. 

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A Day on Venus

One startling difference between a day on Venus compared to Earth starts with sunrise. While we look to the eastern sky, you’d have to face west to see it on the former. That’s because it spins in the opposite direction than our planet, although scientists aren’t sure how to account for the difference.

We know that a solar day is the time it takes for the Earth to rotate completely on its axis, or about 24 hours here. That action doesn’t happen nearly as fast on Venus. A day on this planet would equal about 243 Earth days.

That fact can also explain in part why Venus is virtually inhabitable. It has an extremely high surface temperature that can approach up to 900. Its thick atmosphere of sulfuric acid and carbon dioxide acts as a planetary blanket, trapping the heat.

3D illustration of planet Venus
Image Credit: Whitelion61, Shutterstock

A Year on Venus

We know that a year equals the time it takes for a planet to make a complete revolution around the Sun or 365 days on Earth. We can compare the numbers between our planet and Venus to understand this phenomenon and explain the differences. The orbit distance is almost 93 million miles for the Earth. It is roughly 67 million miles for Venus, or nearly 40% less. That gives the latter an edge.

Then, there is the orbit velocity. While we’re poking around at a mere 66,622 miles per hour, speedy Venus is tearing up the track at 78,339 miles per hour, or over 17% faster. These two sets of figures give Venus a year that lasts 225 Earth days.

Seasons on the Planets

Next, we’ll consider what a year looks like on both planets to put everything in perspective. That begins with the equatorial inclination or the angle with respect to the object’s equator. This figure goes from 0° to 180°. The Earth’s tilt is 23.4393° which explains our four seasons based on how the Sun’s rays are striking our part of the world. It’s a different story with Venus.

Remember that Venus spins in the opposite direction as the Earth, something scientists call a retrograde rotation. Its equatorial inclination is 177.3° which gives it only a minimal tilt of 2.7°. That lack of a significant tilt means that Venus doesn’t experience seasons as we do on Earth. The atmospheric conditions don’t change because of varying Sun rays.

planet venus
Image Credit: ART-ur, Shutterstock

Phases of Venus

Interestingly, Venus experiences different phases, something Galileo Galilei discovered back in the early 1600s. It’s not unlike our Moon that goes from new to full. Instead of the 28 days it takes on Earth, the entire cycle for Venus runs 584 days over four phases. It’s another piece of the puzzle of our nearest planetary neighbor. However, mysteries still remain.

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Final Thoughts

Venus is one of five planets that the Ancients discovered. Its bright light made it impossible not to notice. Yet, as close as it is to Earth, it varies significantly in many ways, including the most fundamental aspects of days and years. Perhaps future space missions will answer the many puzzling questions about Venus. In the meantime, we can continue to look for it in the night sky and wonder about its other secrets.

Featured Image Credit: Artsiom P, Shutterstock

About the Author Chris Dinesen Rogers

Chris has been writing since 2009 on a variety of topics. Her motto with all of her writing is “science-based writing nurtured by education and critical thinking.” Chris specializes in science topics and has a special love for health and environmental topics, and animals of all shapes and sizes.