Unexplained shapes seen on Venus, which some scientists have suggested could be signs of alien life, are even more mysterious than we thought.

Researchers studying the Venusian surface have found that the strange dark spots are affecting the planet's climate, after a new breakthrough study.

Scientists have known about the dark "splotches" on the surface for more than a century, and they change over time. But they have never been explained, with some researchers suggesting they could be evidence of life.

“The particles that make up the dark splotches, have been suggested to be ferric chloride, allotropes of sulfur, disulfur dioxide and so on, but none of these, so far, are able to satisfactorily explain their formation and absorption properties,” said Yeon Joo Lee, the senior author of the new report, in a statement.

Observations show that the particles in those dark spots seem to be the same size, and behave similarly to, the microorganisms that can be found in the Earth's atmosphere. Along with other evidence, that has led to some of the world's most famous scientists including Carl Sagan speculating that the shadowy patches could be life.

Best Nasa pictures of the month - August 2019 Show all 10 1 /10 Best Nasa pictures of the month - August 2019 Best Nasa pictures of the month - August 2019 "When stars like the Sun grow advanced in age, they expand and glow red. These so-called red giants then begin to lose their outer layers of material into space. More than half of such a star's mass can be shed in this manner, forming a shell of surrounding gas. At the same time, the star's core shrinks and grows hotter, emitting ultraviolet light that causes the expelled gases to glow. This type of object is called, somewhat confusingly, a planetary nebula, though it has nothing to do with planets. The name derives from the rounded, planet-like appearance of these objects in early telescopes" - European Space Agency Nasa Best Nasa pictures of the month - August 2019 Two galaxies are seen interacting with one another. This pair of galaxies is known as UGC2369 and they are being drawn together by mutual gravitational attraction. Our own Milky Way galaxy is next expected to interact with another galaxy, the Andromeda, in four billion years. The two galaxies will eventually merge together to form a galaxy that scientists are already calling the Milkomeda Nasa Best Nasa pictures of the month - August 2019 Mount Shasta in California as seen from 260 miles above earth onboard the International Space Station Nasa Best Nasa pictures of the month - August 2019 The galaxy NGC 5866 is seen at a side angle. We're used to seeing galaxies face-on but NGC 5866 is at such an angle to earth that we can only see it edge-on Nasa Best Nasa pictures of the month - August 2019 The most recent portrait of Jupiter taken by the Hubble Telescope shows a more intense colour palette swirling in Jupiter's atmosphere than in recent years. The different colours of the bands help scientists to understand what is happening in Jupiter's atmosphere Nasa Best Nasa pictures of the month - August 2019 This artist's illustration depicts the exoplanet LHS 3844b, which is 1.3 times the mass of Earth and 49 lightyears away. The illustration is based on research by Nasa into this recently discovered planet Nasa Best Nasa pictures of the month - August 2019 A Soyuz spacecraft carrying carg and supplies comes in to dock in the International Space Station Best Nasa pictures of the month - August 2019 A planetary nebula (radiation emitted by a dying star) is seen in the Gemini constellation by the Hubble Telescope Nasa Best Nasa pictures of the month - August 2019 North coast of Africa by Libya and Tunisia as seen from 260 miles above earth onboard the International Space Station Nasa Best Nasa pictures of the month - August 2019 This image from Nasa's Solar Dynamic Observatory shows our Sun in a different light. In colour are active regions of the atmosphere of the Sun e.g. solar flares and coronal mass ejections Nasa

Now researchers have learnt more about how those clouds affect the climate on the planet.

The researchers looked for changes in the planet's "albedo", or how much it absorbs of the light that hits it. They found that it seemed to vary hugely: between 2006 and 2017, the amount of light being reflected back into space halved and then started rising again.

Those changes had a similarly large effect on the amount of solar energy that the clouds absorbed, and therefore how much ciculation there was in the planet's atmosphere. Vigorous activity could be seen in the planet's atmosphere, with clouds that whirled at more than 200 miles per hour, and could be explained by those changes in the clouds.

But, adding to the mystery, scientists still don't know why those dramatic changes are happening.

“That is a striking result,” Limaye adds. “It suggests that something is changing. We can see the change in brightness. If the albedo is changing, something is driving those changes. The question is, what is the cause?”