An image of Venus, made with data recorded by Japan’s Akatsuki spacecraft in 2016, shows swirling clouds in the planet’s atmosphere.
Credit: PLANET-C Project Team/JAXA

Venus is heating up—figuratively, that is. It has always been the hottest planet in the solar system, with surface temperatures of about 870 °F (465 °C). But new findings from the mysterious planet have been pouring in. Soon, a new generation of space probes will transform Venus from a sleepy solar system backwater to a bustling hub of scientific discovery.

Venus is the second planet from the sun. It is known as Earth’s “twin” because the two planets are so similar in size. The diameter of Venus is about 7,520 miles (12,100 kilometers). This diameter is about 400 miles (640 kilometers) smaller than that of Earth. No other planet comes nearer to Earth than does Venus. At its closest approach, it is about 23.7 million miles (38.2 million kilometers) away.

But Venus is better described as Earth’s evil twin, in respect to its withering conditions. In addition to the high temperatures, the atmospheric pressure is 90 times greater than that on Earth. Carbon dioxide makes up most of the atmosphere. The skies are strewn with clouds of sulfuric acid.

Scientists sent several probes to learn more about the planet in the 1960’s and 1970’s. But as space agencies learned of its inhospitable conditions, they concentrated their efforts elsewhere, particularly Mars. The last United States National Aeronautics and Space Administration (NASA) mission to study Venus, called Magellan, launched in 1990. Thus, scientists know relatively little about Venus, despite its close proximity to Earth and its similar size.

Despite the dearth of missions in recent years, planetary scientists continue to scan the planet with Earth-based instruments and reanalyze older data. They have returned surprising results.

Last year, a team of scientists announced that they had discovered a gas called phosphine in Venus’s atmosphere. Many living things on Earth produce phosphine; and scientists have not been able to identify any non-biological processes on Venus that might produce it. This raised the possibility that microbial life could exist in Venus’s atmosphere, where the conditions are much milder. But the discovery has been controversial. Other teams have failed to find any phosphine signature.

Last month, a team led by researchers at Queen’s University Belfast left the floating-Venusian-microbes idea high and dry. They found that Venus’s atmosphere does not contain enough water vapor to support life, irrespective of the presence of phosphine. The team determined that even the most extreme microbes on Earth require an environment with dozens of times more water than is available in Venus’s atmosphere.

Another recent study has shed light onto possible changing of Venus’s surface. Previously, Earth was the only rocky planet known to have a moving surface. A team lead by Paul Byrne, a professor at North Carolina State University, found evidence that parts of Venus’s surface might be slowly moving today. Earth’s crust slowly reshapes itself by a process called plate tectonics. Large pieces of the surface, called plates, subduct (sink) under one another, forming mountain ranges and other features. New crust forms along the ridges where the plates pull away from each other. In contrast, Byrne’s team found that pieces of Venus’s crust move like pack ice in polar oceans. Learning more about crust movement on Venus will help scientists understand how such processes develop on other planets, including Earth and exoplanets that might harbor life.

Last month, space agencies announced that not one, but three missions will be exploring Venus in the next 15 years. On June 2, NASA announced it is sending two mission to Venus. The missions were selected as part of part of NASA’s lower-cost Discovery Program. NASA expects to launch both missions between 2028 and 2030.

VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) will orbit the planet and map its surface with greater detail than ever before. It will allow scientists to better understand the planet’s features.

DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) consists of a sphere that will plunge through Venus’s thick atmosphere, studying the atmosphere’s composition. The DAVINCI+ mission planners are seeking evidence of an ocean of water that might have covered Venus’s surface eons ago.

There are other players in the new Venus boom. Last year, American company Rocket Lab announced plans to launch a small probe to Venus as early as 2023. And on June 10, just over a week after NASA’s selection DAVINCI+ and VERITAS, the European Space Agency (ESA) announced that it would also be sending a probe Venus. The EnVision orbiter will search for signs of current and former tectonic activity and the presence of a past ocean. EnVision is scheduled to arrive at Venus in 2034 or 2035.

The desire to learn more about Venus is fed by more than just curiosity about our nearest neighbor. Astronomers are looking for signs of life on exoplanets. But Venus and Earth would look quite similar from light-years away. Learning more about Venus and how it evolved to become so different from Earth will help astronomers better weed out Venus-like exoplanets in their search for ones that are more like Earth.

An image of Venus, made with data recorded by Japan’s Akatsuki spacecraft in 2016, shows swirling clouds in the planet’s atmosphere.
Credit: PLANET-C Project Team/JAXA

Could there be microscopic life in the clouds of the planet Venus? The idea may seem far-fetched, but in 2020, scientists discovered a tantalizing hint that it could be true, in the form of a strange gas in Venus’s atmosphere.

Venus has been called Earth’s twin. It’s next door to Earth, about the same size as Earth, and covered by an atmosphere of thick, swirling clouds. All of these features made it a tempting target during the early exploration of space. Speculators even imagined dense jungles covering the planet’s surface. When the first landers visited Venus in the 1970’s, however, they revealed a searing environment of 870 °F (465 °C) with pressures 90 times greater than that at Earth’s surface. Clouds of sulfuric acid filled the sky. The search for other life within the solar system quickly shifted to the more temperate Mars.

The new evidence was discovered by an international team of scientists that was actually more interested in exoplanets, planets orbiting distant stars. The team was led by Jane Greaves at Cardiff University in the United Kingdom. Scientists are constantly looking for ways to study exoplanets for signs of alien life. One way is to study the spectra (ranges of light) reflected by exoplanets for clues to chemicals in their atmosphere. One such chemical may be the gas phosphine. On Earth, phosphine is produced by microbes in anaerobic environments—places without oxygen. The gas is short-lived, so to be present in a planet’s atmosphere, it must be replenished continually. So, the presence of phosphine in an exoplanet’s atmosphere could be a sign of ongoing alien life.

The team recorded atmospheric data from Venus in an attempt to establish a benchmark for the spectral signature of an Earth-sized planet without phosphine. To their surprise, their findings indicated that the Venusian atmosphere did contain phosphine. After asking another team of scientists to double-check their results and studying the planet with a more powerful telescope, the evidence of phosphine was confirmed. Scientists do not yet know of a nonbiological way for phosphine to arise on Venus, pointing to the amazing possibility that Venus may harbor microscopic life. If such life exists, it is likely to be found in Venus’s clouds, where conditions are less hellish than those on the surface.

Greaves and her team emphasized that scientists are a long way from determining that there is life on Venus. The authors noted, for example, that sulfur dioxide produces a similar spectral signature to phosphine under certain conditions, raising the possibility that other molecules may mimic phosphine.

January 16, 2017

When it comes to matters of the heart, Aphrodite reigns supreme in Greek mythology. Aphrodite was the Greek goddess of love and beauty. The Romans, who named their gods and goddesses after planets and stars, called her Venus. Aphrodite was the daughter of Zeus, the king of the gods, and the goddess Dione. According to some myths, when Aphrodite was born, she rose full-grown from sea foam. The name Aphrodite may come from the Greek word aphros, which means foam.

This photograph shows a statue of Aphrodite, the goddess of love and beauty in Greek mythology. Aphrodite plays a role in many myths, often starting love affairs among mortals. Credit: © Thinkstock

In ancient Greece, Aphrodite wore many hats, so to speak. For instance, the Greeks worshiped her as a universal goddess called Urania, which means queen of heaven. She was also worshiped as a goddess of civic life called Pandemos, which means goddess of all people. Some Greeks considered Aphrodite to be the goddess of seafaring and warfare.

According to mythology, Aphrodite delighted in instigating love affairs between the gods and mortals—affairs that often included her. She was married to Hephaestus, the blacksmith of the gods, but Aphrodite had many lovers among the gods, as well as among mortal men. Her lovers included Ares, the god of war, and the mortal Anchises, a Trojan prince with whom she had a famous son, Aeneas. Her most famous lover, however, was the handsome and youthful mortal Adonis. Aphrodite was so attracted by his good looks that her jealous husband, Hephaestus, disguised himself as a boar and killed Adonis. Supposedly, a flower called the anemone sprang up either from Aphrodite’s tears over the death of Adonis or from the handsome mortal’s spilled blood. Even today, the red anemone is considered a symbol of the death of a loved one, or of forsaken love.

June 4, 2012

Venus will make a rare and historic journey across the face of the sun this week, an event that people alive today will almost certainly never have another chance to see. That journey, called a transit, will mark Venus’s passage between Earth and the sun, an astronomical event that comes along only about every 110 years. During the transit, Venus will appear as a dark dot moving across the sun’s disk. The transit can be seen on June 5 in much of the Western Hemisphere and on June 6 in a large part of the Eastern Hemisphere. Transits of Venus happen in pairs about eight years apart. The first of the current pair was in 2004. The previous transit occurred in 1882; the next won’t occur until December 10-11, 2117.

Venus appears as a dark dot moving across the sun's disk during a transit. Venus transits occur in pairs in which one transit happens 8 years after the other. (Jay M. Pasachoff, et al., Williams College Transit of Venus Team with John Seiradakis, et al., Aristotelian University, Thessaloniki, Greece)

A transit of Venus is an amazing astronomical display–and much more. While trying to determine how the planets move around the sun, the great German astronomer and mathematician Johannes Kepler became the first to predict a transit of Venus. But he died soon before the transit and no record of that event exists. However, the English astronomers Jeremiah Horrock and William Crabtree recorded the 1639 event.

In 1716, the English astronomer Edmond Halley proposed that the transit of Venus could be used to determine the distance between Earth and the sun. He suggested that by measuring the duration and time of the transit from many different locations, scientists could triangulate that distance. Unfortunately, measurements made during the next transit, in 1761, were insufficient.

Fortunately, the transit eight years later sparked a worldwide interest in the project. Scientists and other interested people scattered to the far reaches of the globe to gather the needed information. Among the observers was the English explorer James Cook. On orders from the Royal Navy, he traveled to the South Pacific island of Tahiti to make the observations. All the data gathered during the transit enabled scientists to calculate that Earth was 95 million miles (153 million kilometers) from the sun (very close to the actual distance of about 93 million miles [150 million kilometers]).

Scientists plan to use the 2012 transit to help in the search for extrasolar planets. Since 2009, NASA’s Kepler space telescope has been watching for small changes in the brightness of alien stars caused by the transit of an orbiting planet. By analyzing the starlight passing through the extrasolar planet’s atmosphere during the transit, scientists can learn about the chemicals in its atmosphere. During the transit of Venus, scientists will be studying Venus’s atmosphere with the Hubble Space Telescope. Although that planet’s atmosphere is already well understood, the information may help them determine the composition of extrasolar atmospheres.

Here are a few ways to view the transit safely. WARNING: NEVER LOOK DIRECTLY AT THE SUN.
1)    Wear solar eclipse shades, also called “solar filters,” which can be found online and in some science stores. Welders goggles rated “14″ or higher will also protect your eyes.
2)    Make a pinhole projector. Use two pieces of cardboard; punch a small hole in one of them. Hold this piece up to the sun so that sunlight passes through the hole and casts an image on the other piece.
3)    Use a telescope as a projector. You can do this by pointing the telescope at the sun and then projecting the image in the eyepiece onto any nearby flat surface, such as a wall or a piece of cardboard or paper. You can also use a pair of binoculars. Use only one side and cover the other side. (You could use both sides to make two images.)
4)    Watch the live webcast from atop Mauna Kea in Hawaii sponsored by NASA EDGE: http://sunearthday.nasa.gov/2012/transit/webcast.php.

Additional World Book articles:

• Space exploration (Probes to Venus and Mercury)
• Spectrometer
• In Search of Other Worlds (a Special Report)

Feb. 16, 2012

To the surprise of scientists, data from the Venus Express space probe have indicated that Venus is rotating much more slowly than it was only 16 years ago. As a result, a day on Venus is now an average of 6.5 minutes longer. Why? For now, scientists are puzzled, though the reason may lie in the thick blanket of clouds that has long kept the planet shrouded in mystery.

The discovery of the slowdown was announced by scientists with the European Space Agency (ESA) who have been using an infrared device on the Venus Express to study surface features on the planet. A comparison of these images with radar maps of Venus made by NASA‘s Magellan spacecraft in the 1990′s at first caused the ESA scientists to think their calculations were seriously wrong.  During Magellan’s four-year mission, scientists had determined the length of a Venusian day by measuring the speed at which surface features passed beneath the orbiting probe. ESA scientists were confident that the Magellan measurements were accurate. But now, certain features were up to 12.4 miles (20 kilometers) away from where the ESA scientists thought they would be. Additional checks for possible errors led the scientists to conclude that the planet was, in fact, rotating more slowly. Since 1996, the length of a day on Venus has increased from an average of 243.0185 Earth days to an average of 249.5185 Earth days.

Thick clouds of sulfuric acid cover Venus, hiding its surface from most forms of light. The Pioneer Venus 1 orbiter took these pictures of the planet's atmosphere in ultraviolet light. Many kinds of light cannot penetrate the clouds. To map the surface, astronomers rely on spacecraft instruments that use radio waves, such as radar. NASA

Venus’s incredibly dense atmosphere may explain the mysterious slowdown. The atmospheric pressure on Venus is a crushing 90 times as great as the pressure at sea level on Earth. At the cloud tops, winds often blow at hurricane-force speeds of 200 miles (320 kilometers) per hour. Some scientists have speculated that friction between the surface and the turbulent atmosphere may be slowing the planet. They also suggested that the slower rotation rate may be part of a long-term weather cycle. The length of a day on Earth may also vary because of tides and winds. But on our home planet, a day may change by only a millisecond a year.

Additional World Book articles:

• Solar system
• Space exploration