Astronomers have uncovered hidden details of Mercury's surface and measured the planet's temperature (photo).

The European Space Agency (ESA) and Japan Aerospace Exploration Agency (JAXA) spacecraft BepiColombo made its fifth flyby of Mercury on December 1. For the first time in history, it captured the surface of the small planet in the mid-infrared wavelength range. With the help of new images, scientists gained a more accurate understanding of the temperature and composition of the surface of the planet closest to the Sun, reports Gizmodo.

The BepiColombo spacecraft was launched in October 2018 and is expected to arrive at Mercury in November 2026, about a year later than initially planned. To enter orbit around Mercury, the spacecraft utilizes the gravity of Venus and Mercury, which helps adjust its trajectory and slow down its flight speed. On December 1, BepiColombo performed its fifth gravity assist maneuver around Mercury and, using the MERTIS instrument, provided new data about the planet that were previously unknown.

For the first time, scientists observed Mercury's surface in the mid-infrared wavelength range, allowing them to obtain more detailed information about the temperature of the small planet, its cratered surface, and its composition.

According to scientists from ESA, they have never been closer to understanding the composition of Mercury's surface than they are now. The preliminary data is very important, as it will help better interpret the information that will be obtained after BepiColombo enters orbit around Mercury. Thanks to the new images, scientists were able to distinguish different impact craters that were only visible as dark spots in visible light.

Researchers state that they have observed surface features of Mercury that had previously gone unnoticed. The new images of Mercury reveal which parts of the planet's surface shine brighter than others in the mid-infrared range of light. The brightness of the surface depends on temperature, surface roughness, and the minerals it consists of. The MERTIS instrument is designed precisely to determine the composition of the surface of the planet closest to the Sun. This is one of the many mysteries of Mercury that astronomers aim to solve.

Past observations of Mercury have shown that there is relatively little iron on the planet's surface, even though Mercury has an unusually large core made of nickel and iron for its size. Scientists also know that despite the scorching rays of the Sun causing some chemical elements on the surface to easily evaporate, there are still many of them present.

Using the MERTIS instrument, scientists also obtained more accurate data regarding the surface temperature of Mercury. It turns out to be 420 degrees Celsius. This is not surprising, as this planet is located about three times closer to the Sun than Earth. At the same time, Mercury is not the hottest planet in the Solar System. That title belongs to Venus, where the temperature exceeds 460 degrees Celsius. Although this planet is farther from the Sun, the intense greenhouse effect results in such a high temperature.

Mercury is the least studied rocky planet in the Solar System. BepiColombo is only the third spacecraft in history that will study the planet from close range starting in 2026. It is also only the second spacecraft to enter orbit around Mercury.

Between 1972 and 1975, the NASA spacecraft Mariner 10 flew past Mercury, while the NASA spacecraft Messenger orbited the planet from 2011 to 2015.