Venus: You can sometimes see Venus in the west just after sunset. When Venus is visible in that part of the sky, it is known as the “evening star,” though of course it really isn’t a star at all. At other times, Venus rises before the sun in the morning. Then it is known as the “morning star.”
Venus is so similar in size and mass to Earth that it is sometimes called “Earth’s twin.” Venus’s density and internal structure are similar to Earth’s. But, in other ways, Venus and Earth are very different.
Venus’s Rotation: Venus takes about 7.5 Earth months to revolve around the sun. It takes about 8 months for Venus to rotate once on its axis. Thus, Venus rotates so slowly that its day is longer than its year! Oddly, Venus rotates from east to west, the opposite direction from most other planets and moons. Astronomers hypothesize that this unusual rotation was caused by a very large object that struck Venus billions of years ago. Such a collision could have caused Venus to change its direction of rotation. Another hypothesis is that Venus’s thick atmosphere could have somehow altered its rotation.
Venus’s Atmosphere: Venus’s atmosphere is so thick that it is always cloudy there. From Earth or space, astronomers can see only a smooth cloud cover over Venus. The clouds are made mostly of droplets of sulfuric acid.
If you could stand on Venus’s surface, you would quickly be crushed by the weight of its atmosphere. The pressure of Venus’s atmosphere is 90 times greater than the pressure of Earth’s atmosphere. You couldn’t breathe on Venus because its atmosphere is mostly carbon dioxide.
Because Venus is closer to the sun than Earth is, it receives more solar energy than Earth does. Much of this radiation is reflected by Venus’s atmosphere. However, some radiation reaches the surface and is later given off as heat. The carbon dioxide in Venus’s atmosphere traps heat so well that Venus has the hottest surface of any planet. At 460°C, its average surface temperature is hot enough to melt lead. This trapping of heat by the atmosphere is called the greenhouse effect.
Exploring Venus:
Many space probes have visited Venus. The first probe to land on the surface and send back data, Venera 7, landed in 1970. It survived for only a few minutes because of the high temperature and pressure. Later probes were more durable and sent images and data back to Earth.
The Magellan probe reached Venus in 1990, carrying radar instruments. Radar works through clouds, so Magellan was able to map nearly the entire surface. The Magellan data confirmed that Venus is covered with rock. Venus’s surface has many volcanoes and broad plains formed by lava flows.
Reading check point:
What are Venuses clouds made of?
Venus is so similar in size and mass to Earth that it is sometimes called “Earth’s twin.” Venus’s density and internal structure are similar to Earth’s. But, in other ways, Venus and Earth are very different.
Venus’s Rotation: Venus takes about 7.5 Earth months to revolve around the sun. It takes about 8 months for Venus to rotate once on its axis. Thus, Venus rotates so slowly that its day is longer than its year! Oddly, Venus rotates from east to west, the opposite direction from most other planets and moons. Astronomers hypothesize that this unusual rotation was caused by a very large object that struck Venus billions of years ago. Such a collision could have caused Venus to change its direction of rotation. Another hypothesis is that Venus’s thick atmosphere could have somehow altered its rotation.
Venus’s Atmosphere: Venus’s atmosphere is so thick that it is always cloudy there. From Earth or space, astronomers can see only a smooth cloud cover over Venus. The clouds are made mostly of droplets of sulfuric acid.
If you could stand on Venus’s surface, you would quickly be crushed by the weight of its atmosphere. The pressure of Venus’s atmosphere is 90 times greater than the pressure of Earth’s atmosphere. You couldn’t breathe on Venus because its atmosphere is mostly carbon dioxide.
Because Venus is closer to the sun than Earth is, it receives more solar energy than Earth does. Much of this radiation is reflected by Venus’s atmosphere. However, some radiation reaches the surface and is later given off as heat. The carbon dioxide in Venus’s atmosphere traps heat so well that Venus has the hottest surface of any planet. At 460°C, its average surface temperature is hot enough to melt lead. This trapping of heat by the atmosphere is called the greenhouse effect.
Exploring Venus:
Many space probes have visited Venus. The first probe to land on the surface and send back data, Venera 7, landed in 1970. It survived for only a few minutes because of the high temperature and pressure. Later probes were more durable and sent images and data back to Earth.
The Magellan probe reached Venus in 1990, carrying radar instruments. Radar works through clouds, so Magellan was able to map nearly the entire surface. The Magellan data confirmed that Venus is covered with rock. Venus’s surface has many volcanoes and broad plains formed by lava flows.
Reading check point:
What are Venuses clouds made of?
