The Galileo spacecraft was launched into space in the fall of 1989 with the goal of visiting Jupiter and its moon system. Galileo had to travel throughout the inner solar system to obtain sufficient speed to reach Jupiter due to the huge distance to the king of planets. He flew past Venus in 1990 and Earth in 1990 and 1992. Galileo photographed our globe on multiple occasions during his flybys, and these photographs have been utilized by astronomers to identify life on Earth.
While it may sound absurd to think that life could be “discovered” on Earth in the twenty-first century, the study will be helpful to astronomers looking for extraterrestrial life. photographs from Galileo can be used as a test bed to compare with photographs of exoplanets because we now know there is life on Earth in addition to the topography and diversity of the planet.While direct imaging of certain exoplanets is still in its infancy, astronomers are still figuring out what information those photos might contain.
The group therefore concentrated on what are referred to as disk-integrated images in this study. Here, a planet’s light is seen as a whole. The scientists examined integrated images from the Limited Solid State Imager (SSI) rather than a detailed view of Earth like the one above. Its disk-integrated photos are comparable to those that it can obtain from exoplanets. After that, they examined the photos’ spectra and overall brightness to see what they could reveal about Earth.
The authors discovered, among other things, that a large portion of the spectrum information in the integrated images is washed out, making it challenging to distinguish specific biosignatures. That was to be expected, given that the Galileo cameras were designed with Jupiter in mind, which is considerably dimmer due to its greater distance from the Sun. But the team was able to find an oxygen absorption line, confirming that the atmosphere of our planet is rich in oxygen. Although it’s a wonderful beginning, the existence of oxygen by itself does not establish that life existed on Earth.
More intriguingly, the group was able to see how Earth’s reflective brightness, or albedo, changes with rotation. They may infer a very basic concept of the Earth’s oceans and continents from this. They might demonstrate that Earth’s composition of landmasses and oceans makes it suitable for human habitation.
The primary advantage of this research and similar ones is that they establish a baseline for exoplanets that may be habitable. From a distance and with low resolution, this is the appearance of a planet that could support life. Astronomers will know they are headed in the correct direction when they locate exoplanets that resemble one another.