Venus, the second planet from the Sun and our neighbour astronomically speaking, is often described as the ‘evening star’. It is intensely bright and can often be seen shortly after sunset, following the setting Sun across the horizon. In the coming months it will be easy to spot in the west during twilight.

Venus is the third-brightest object in the sky – after the Sun and Moon.

Pictured: Photograph of Venus taken by the Mariner 10 spacecraft, showing the top of the dense cloud cover. The pale yellow colours are the reflection of sunlight off clouds comprising droplets of highly corrosive sulfuric acid. (Image credit: NASA).

It was its graceful splendour in the twilight sky that led the Babylonians, Greeks and Romans to consider it worthy of being named after a major deity, the goddess of love and beauty. Indeed, the only planet to be named after a goddess.

It is also often called Earth’s twin or sister planet. It is comparable in size and a rocky planet of similar mass and density. But the similarities end there as it has an extreme atmospheric pressure of about 90 times that of Earth – almost the equivalent of a column of water nearly 1km deep. 

Pictured: Venus in the western twilight sky between May and July. As the planet wanes, it will move closer to Earth, appearing larger and brighter. It will gradually decrease in altitude, eventually disappearing from the evening sky. (Image credit: JM Dean/NASA).

The thick atmosphere, dominated by carbon dioxide, has led to a “runway greenhouse” effect, trapping heat and resulting in a surface temperature of around 470 degrees Celsius – hot enough to melt lead!

There is no danger of Earth suffering a similar fate as the extreme conditions are the result of intense volcanic activity coupled with a lack of any natural carbon dioxide recycling processes. There is evidence of some 85,000 ancient volcanoes on Venus, with only 37 active today, although there may be a few thousand in a dormant state. Current research suggests that Venus went through an extreme global resurfacing event 300 to 600 million years ago. Prior to this, it was possible that Venus might have been a water world similar to Earth. This poses the question: could life have existed on our sister planet?

Pictured: One of a handful of photographs of the surface of Venus taken in 1982 by the Russian Venera 13 probe which survived on the surface for only 127 minutes before it succumbed to the extremely harsh environment. (Image credit: Russian Academy of Sciences/Venera Team/Don P. Mitchell).

Venus is exceptionally bright because of a combination of its proximity to both the Sun and Earth and the extremely dense cloud cover which reflects some 70% of the sunlight. 

For the next three months Venus will look splendid in the western sky during dusk and into the late evening darkness.

If you have a pair of binoculars or a telescope, you will see it has phases, as the portion illuminated from our perspective changes, similar to the Moon. However, the complete cycle takes approximately 584 days, while our Moon takes just a month.

Pictured: Venera 13 probe and its protective atmospheric entry vehicle designed to withstand the high pressures and temperatures and atmospheric clouds of sulfuric acid. (Image credit: Russian Academy of Sciences/Venera Team/Don P. Mitchell).

In 1610, Galileo Galilei observed the Venusian phases, adding further evidence to the belief that the planets orbited the Sun and not the Earth as believed at the time.

Between May and July Venus will weave through the Zodiacal constellations of Taurus, Gemini, Cancer and Leo as we move into the summer. It will then set below the horizon and re-appear in November as the “morning star” preceding the sunrise. 

Particularly notable dates to view Venus are the 18, 19 and 20 May and 16, 17 and 18 June, when Venus will be joined by the largest of the planets, Jupiter, and a beautiful waxing crescent Moon resplendent with earthshine gently illuminating the dark portion. Find a location with a good view to the west and enjoy the spectacle during dusk and evening darkness. 

Pictured: Venus, Jupiter and the crescent Moon between 18 and 20 May. (Image credit: JM Dean).

Despite the less than hospitable surface conditions on Venus, in 2020 astronomers announced the detection of phosphine gas within the middle/lower cloud layer in the Venusian atmosphere. On Earth, phosphine is either manufactured by humans for industrial use or produced through biological activity. On Venus, the phosphine is within a temperate mid-to-high cloud layer where the atmospheric pressure is similar to Earth’s and temperatures are about 50/60 degrees Celsius. Thus, it could potentially represent microbial activity, possibly a last relict of life from a period when Venus had oceans.

This discovery has led to a flurry of missions to Venus. One scheduled to tentatively launch in the summer this year is the Venus Life Finder, a private joint mission by the Rocket Lab Corporation  and Massachusetts Institute of Technology. The journey time is expected to be four or five months, so it could arrive late this year or early next year. Other missions include NASA’s Davinci mission scheduled to launch in 2029 and the European Space Agency’s EnVision mission scheduled to launch in 2031. For young budding astronomers still at school there could be some exciting planetary science in the next couple of decades.

Pictured: Synthetic image of Venus compiled from NASA’s Magellan and Pioneer Venus Orbiter data with images collected by the Russian Venera 13 and 14 spacecraft. The river-like structures are lava flows that can extend for thousands of kilometres. (Image credit: NASA/JPL).

If you want to learn more about our Solar System, then go to https://science.nasa.gov/solar-system/. To learn more about the night sky, look for apps on your phone. Good ones are Celestron Sky Portal, SkySafari and Stellarium.

Dr Jean Dean, FRAS