Venus: Earth's Scorching Twin

Look west after sunset at the right time of year and you may see a brilliant white "star" that outshines everything else in the sky except the Moon.

That is Venus, our closest planetary neighbor and, in size and makeup, the planet most like Earth.

Yet under its bright clouds lies one of the most hostile places in the solar system.

Here is why Venus is called Earth's twin, how it became a planet-wide oven,

what spacecraft found on its surface and how to get the best views of it from your own backyard.

Why Venus Is Called Earth's Twin

On paper, Venus and Earth look like siblings.

They are nearly the same width, have similar masses and are both built from rock around an iron core.

Venus also comes closer to Earth than any other planet does.

The resemblance ends quickly once you look past the basic measurements, as the comparison below shows.

A Runaway Greenhouse

Venus is the hottest planet in the solar system, even though Mercury is closer to the Sun.

The reason is its atmosphere.

Carbon dioxide lets sunlight reach the ground but traps the heat that the ground gives off,

and on Venus there is so much of it that the heat has almost no way out.

The result is a surface temperature of about 465 °C (870 °F), hot enough to melt lead.

Because the thick air spreads heat so efficiently, the temperature barely changes between day and night or between the equator and the poles.

There is no cool place to hide anywhere on the planet.

Scientists call this a runaway greenhouse effect.

One widely discussed idea is that young Venus may have had water, possibly even shallow oceans,

but as the Sun slowly brightened, that water evaporated. Water vapor trapped even more heat, the oceans boiled away completely,

and sunlight eventually broke the water molecules apart so the hydrogen escaped to space.

How much water Venus ever had is still debated.

Clouds of Acid and Crushing Pressure

The whole planet is wrapped in a thick deck of clouds made largely of sulfuric acid droplets.

They reflect most of the sunlight that hits them, which is why Venus looks so dazzling from Earth,

and they completely hide the surface from ordinary telescopes.

Beneath the clouds, the atmosphere is incredibly dense.

Standing on the surface would feel like being about 900 meters (3,000 feet) underwater in Earth's oceans.

Any visitor would be crushed, cooked and corroded at the same time.

The upper atmosphere also behaves strangely.

High-altitude winds whip around the entire planet in about four Earth days, far faster than the solid planet turns beneath them.

Scientists call this super-rotation, and exactly how it is maintained is still being studied.

A Planet That Spins Backward

Venus rotates in the opposite direction from most planets, and it does so extremely slowly.

One full turn takes about 243 Earth days, which is longer than its 225-day year.

If you could see through the clouds, the Sun would rise in the west and set in the east,

with the time from one sunrise to the next lasting about 117 Earth days.

No one knows for certain why Venus spins this way.

Possible explanations include a giant impact early in its history or the gradual effects of the Sun's gravity pulling on its massive atmosphere over billions of years.

Volcanoes and a Young Surface

Radar can see through the clouds, and radar maps show a world shaped by volcanism.

Venus is covered in vast lava plains, and it has more volcanoes than any other planet,

including broad shield volcanoes and unusual pancake-shaped domes formed by thick, sticky lava.

The surface has surprisingly few impact craters, and the craters it has are spread fairly evenly.

That suggests much of the surface was paved over by lava within the last several hundred million years, which is young in geological terms.

Studies that re-examined Magellan's radar images have found signs that some volcanoes may still be active, although that remains an open question.

Visiting Venus: Landers and Radar Maps

Venus was the first planet explored by spacecraft. Highlights include:

• Mariner 2, which flew past Venus in 1962 and became the first successful mission to another planet, confirming its extreme heat.
• The Soviet Venera landers, which made the first successful landing on another planet in 1970 and sent back the first pictures from the surface in 1975. Even the hardiest of them kept working on the surface for only about two hours before the heat and pressure overwhelmed it.
• Magellan, a NASA orbiter that used radar in the early 1990s to map almost the entire surface in detail.

The Venera images show a flat, rocky landscape under an orange-tinted sky, lit by a dim glow filtered through the clouds.

How to Enjoy Venus From Your Backyard

Venus is the easiest planet to find because it is the brightest.

It often appears as the "evening star" in the west after sunset or the "morning star" in the east before dawn,

depending on where it is in its orbit.

• Look in twilight. Venus is visible while the sky is still fairly bright, often before any stars appear.
• Watch its phases. Through a small telescope or steady binoculars, Venus shows phases like the Moon, from a full disk to a thin crescent.
• Notice how its size changes. As a crescent, Venus is closest to us and looks much larger than when it is nearly full on the far side of the Sun.
• Keep the Sun out of view. When Venus is close to the Sun in the sky, wait until the Sun has fully set before using optics, and never look at the Sun without certified solar filters.

Frequently Asked Questions

Why is Venus so bright?

Three things combine: it is relatively close to both the Sun and Earth, and its thick clouds reflect most of the sunlight that reaches them.

Apart from the Sun and the Moon, nothing natural in the sky shines brighter.

Could humans ever land on Venus?

Not on the surface with any technology we have today.

The heat, pressure and acid clouds destroy even robotic landers within hours.

Some scientists have studied the idea of floating stations high in the atmosphere,

where the temperature and pressure are far milder, but that remains a concept.

Is there life on Venus?

There is no evidence of life on Venus.

The surface is far too hot, but some researchers have wondered whether microbes could survive in the milder cloud layers.

A report of phosphine gas in the clouds in 2020 drew wide attention, but those findings have been heavily disputed.

The Bottom Line

Venus shows how two planets can start out similar and end up worlds apart. Its story of runaway heat is also a lesson in how powerfully an atmosphere shapes a planet.

Next time you spot that brilliant light in the twilight, you will know it is a near-twin of Earth hiding a furnace beneath its clouds.