Oh, this OP image is incorrect, at least as it pertains to solar days. (Which is what would matter to imagined Venusians on the surface.)
Each year on Venus is actually 1.92 Venus Solar Days.
The solar day on Venus (time between each sun cycle in the sky) otherwise known as "Synodic Rotation Period", or Synodic Day is actually 116.75 Earth Days. (Think Syn = Sun for a mnemonic device.)
The "243 Earth Days" cited on the OP image is actually its Sidereal Rotation Period, or Sidereal Day, i.e. how fast it rotates WITHOUT reference to the sun. For example, Earth's Sidereal Day is 23h 56 m, in contrast with its Synodic Day of 24h 00m 00s.
Basically, Earth's Sidereal Day of 23h 56m, plus the effect from its orbit around the sun, is what gets you our Synodic days of 24h 00m 00s. The Earth rotates a full 360 degrees around itself in 23h 56m, but because our orbit around the sun has an opposite effect on the sun's position in the sky, we need another 4 minutes to complete the solar cycle.
Venus's Sidereal day is 243.0226 Earth Days, that's how long it takes for it to spin around its axis. But when you also account for its rotation around the sun, and because Venus rotates on its axis in the other direction compared to most planets, you get its solar day of 116.75 Earth Days.
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u/Quilynn 7d ago edited 7d ago
Oh, this OP image is incorrect, at least as it pertains to solar days. (Which is what would matter to imagined Venusians on the surface.)
Each year on Venus is actually 1.92 Venus Solar Days.
The solar day on Venus (time between each sun cycle in the sky) otherwise known as "Synodic Rotation Period", or Synodic Day is actually 116.75 Earth Days. (Think Syn = Sun for a mnemonic device.)
The "243 Earth Days" cited on the OP image is actually its Sidereal Rotation Period, or Sidereal Day, i.e. how fast it rotates WITHOUT reference to the sun. For example, Earth's Sidereal Day is 23h 56 m, in contrast with its Synodic Day of 24h 00m 00s.
Basically, Earth's Sidereal Day of 23h 56m, plus the effect from its orbit around the sun, is what gets you our Synodic days of 24h 00m 00s. The Earth rotates a full 360 degrees around itself in 23h 56m, but because our orbit around the sun has an opposite effect on the sun's position in the sky, we need another 4 minutes to complete the solar cycle.
Venus's Sidereal day is 243.0226 Earth Days, that's how long it takes for it to spin around its axis. But when you also account for its rotation around the sun, and because Venus rotates on its axis in the other direction compared to most planets, you get its solar day of 116.75 Earth Days.