The phrase “airless moon” is a bit of an oxymoron because the Moon does have an atmosphere.
It has many layers of the atmosphere and a complex weather system of winds, rain, and clouds. The Earth’s magnetic field plays an essential role in regulating the temperature and composition of this atmosphere.
The Moon is not only very different from our planet in appearance but also in composition. Our Earth is chemically richer than our Moon because it has been under the influence of water for billions of years to strip away volatile elements that could evaporate into space. On the other hand, the Moon has not been influenced by water for billions of years and is thus chemically impoverished because it has no water and cannot replenish its evaporated elements.
The surface gravity of the Moon is 1/6 that of the Earth, so getting around on the Moon is a lot more challenging than on Earth. Although we have sent rovers to explore our lunar neighbor, they were only able to travel a few dozen kilometers each time and had to be remotely operated from Earth.
The next manned mission to analyze the lunar atmosphere will be in 2026 when NASA plans to launch a new generation lunar rover that will be developed aboard the International Space Station (ISS) and deployed onto the Moon from there. The new rover has enough range to travel 300 kilometers from the landing site and take samples from different sites on the Moon.
Scientists think that the oxygen component of the lunar atmosphere is produced by outgassing from lunar rocks, which are rich in oxygen and other volatile elements like silicon, magnesium, and aluminum. The European Space Agency’s BepiColombo mission will launch in 2018 and arrive at the Moon in 2026. This robotic mission will not only further study the composition of this atmosphere but also conduct a detailed analysis of how it was formed over billions of years since the origin of our Moon.
On July 29, NASA launched the Parker Solar Probe to study the Sun. It will eventually travel close to our star’s atmosphere and be able to collect data on the solar wind and its magnetic field. The spacecraft also carries instruments to measure charged particles and magnetic fields around the Sun to understand these phenomena better.
The Parker Solar Probe has already made a historic first by flying directly through the Sun’s outermost atmosphere on Oct. 29, 2018, a feat that took it to record-breaking speeds of 202 miles per second (325 km/s).
Although the Sun is relatively calm in comparison to other stars, it has its own atmosphere and an extreme gravity to contend with. The main reason that the Earth and Moon orbit around their Sun is that without that force, they would be torn apart by tidal forces.
The Parker Solar Probe will continue its journey in 2018; perhaps by then, we will also have found the airless Moon. The scientists hope that the Moon’s atmosphere will help them better understand how the solar wind moves around the Sun, which is a valuable milestone for our understanding of stellar physics. The more they can learn about stellar physics, the more they will understand how the universe works.
The volume of water vapor in the atmosphere is higher on Mars than it is on Earth because carbon dioxide (which makes up about 90 percent of the dry Martian atmosphere) has been depleted and has not been replaced by other gases such as methane (CH 4). When the temperature is below freezing (31°F, or −0.5°C), carbon dioxide can be trapped in a solid form called dry ice. Therefore, it is surprising that Mars has a lot more water vapor in its atmosphere, as measured by the Mars Global Surveyor and the Viking landers, because meteorite impacts would deliver enough ice to form oceans on its surface. The Phoenix mission has found small amounts of methane in the Martian atmosphere. Still, measurements from Earth-based telescopes showed that this methane was being destroyed rapidly by sunlight and could not explain how much water vapor was on its surface.