Which planet is covered by thick white and yellowish clouds of sulphuric acid?

Venus, the second planet from the Sun, is covered by a thick layer of clouds made mainly of droplets of sulphuric acid. These clouds are highly reflective and give the planet its bright, pale yellowish-white appearance. They completely hide the surface from view in visible light.

Venus has the densest atmosphere of all the rocky planets. It is made up of about 96.5% carbon dioxide, with some nitrogen. The atmospheric pressure at the surface is about 92 times that on Earth, equal to the pressure about 900 metres under the sea.

Because of the thick carbon dioxide atmosphere, Venus has an extreme greenhouse effect. Heat from the Sun is trapped, making Venus the hottest planet in the solar system, with an average surface temperature of about 465°C, hot enough to melt lead. This is hotter than Mercury, even though Mercury is closer to the Sun.

Other interesting facts about Venus:

It is the brightest planet in the night sky and, after the Moon, the brightest natural object. It is often called the "Morning Star" or "Evening Star", because it is seen near the horizon before sunrise or after sunset.

It is called the "Earth's twin" or "sister planet" because it is similar to the Earth in size, mass and density. It is also the planet that comes closest to the Earth.

It rotates very slowly and in the opposite direction (retrograde rotation) compared with most planets. As a result, on Venus, the Sun rises in the west and sets in the east. A day on Venus (243 Earth days for one rotation) is longer than its year (about 225 Earth days).

It has no moon and no rings (Mercury also has none).

Spacecraft that studied Venus include the Soviet Venera missions (Venera 7 made the first soft landing on another planet in 1970), NASA's Magellan, and Japan's Akatsuki. ISRO has planned a Venus Orbiter Mission (Shukrayaan), approved in 2024.

Why not the other options?

• ✗Mars has a thin carbon dioxide atmosphere and is called the "Red Planet" because of iron oxide (rust) on its surface.
• ✗Mercury has almost no atmosphere.
• ✗Saturn is a gas giant with clouds of ammonia, famous for its rings.