The European Space Agency’s Venus Express spacecraft has discovered an ozone layer high in the sweltering atmosphere of Venus, a new study reveals.

The discovery will help astronomers better understand the composition of Venus’ murky atmosphere, and by comparing it with the atmospheres of Earth and Mars, the findings could even help shape the search for life on other planets, the researchers said.

“This detection gives us an important constraint on understanding the chemistry of Venus’s atmosphere,” study leader Franck Montmessin, of the Laboratoire Atmosphères, Milieux, Observations Spatiales  in France, said in a statement.

The probe’s spectroscopic instrument scrutinized the starlight for key characteristics of gases in the atmosphere as it is absorbed at different wavelengths. The instrument discovered the ozone because it absorbed some of the ultraviolet light from the stars, the researchers said.

The discovery will help scientists better characterize the chemistry of Venus’ atmosphere, but it could also be useful for astronomers searching for life on other worlds, the researchers said. By comparing the properties of Venus’ atmosphere with equivalent layers of the atmospheres of Earth and Mars, scientists could narrow down their search for life on other planets, Montmessin explained.

To date, ozone has only previously been found in the atmospheres of Earth and Mars. On Earth, it plays a critical role because it protects life on the planet by absorbing much of the sun’s harmful ultraviolet rays. Furthermore, it is thought to have been generated by life itself, the researchers said.  Venus is thought to have built up its ozone by nonbiological means. The ozone layer on Venus sits 100 kilometers above the planet’s surface, which is roughly four times higher in the atmosphere compared with Earth, and is also a hundred to a thousand times less dense.

Astrobiologists have theorized that a planet’s ozone concentration must be about 20 percent of Earth’s value before life should be considered as a cause. The results of this new study line up with this theory, since Venus remains well below this threshold.