June 28, 2022
It looks like the earth, but it rains lava;  Learn more about the planet

It looks like the earth, but it rains lava; Learn more about the planet

US space agency scientists NASA preparing to use James Webb Powerful Telescope To explore a planet that is relatively close to Earth and has similar characteristics. There is one big difference: it is possible that the rain there was made of lava.

This exoplanet (55 Cancri e) (also classified as exoplanet) orbits a star only 40 light-years away, so close that it can be seen with the naked eye in the sky, in the constellation Cancer.

A tweet spread commenting on his characteristics social networksbut the discovery of 55 Cancri e is not recent: astrophysicists have known of its existence since 2004. What is new is that NASA will use the James Webb Telescope to study it more closely.

And not only him: on May 26, NASA announced which will be used by James Webb to study LHS 3844b as well. Scientists call the two exoplanets “super-Earths” because they are rocky and close in size to our planet, but they have harsh geological and climatic conditions.

Super Earth, so hot

55 Cancri e is located only 2.4 million kilometers from its star, which is also similar to our Sun. This means that there is a year that ends after 18 hours.

Because it is so close to its star, the heat is so intense that despite being a rocky planet, any metal on the surface would exceed its melting point. Therefore, scientists believe that it is covered with oceans of lava.

It was believed that, since it was so close to its star, 55 Cancri, it did not rotate (rotate on its axis), but always had one side facing the “sun” and the other in eternal darkness.

But observations made with NASA’s Spitzer Space Telescope have raised more questions than answers about this giant Earth. The astronomers note that the hottest point on 55 Cancri is not the point that receives the most heat from the Sun directly. Moreover, the temperature on the putative “daily side” of an exoplanet varies over time.

One explanation for this is that the planet has a dynamic atmosphere that drives heat. “55 Cancri e may have a thicker atmosphere dominated by oxygen or nitrogen,” says Renew Ho of NASA’s Jet Propulsion Laboratory, who leads the team that will use the James Webb Infrared Camera (NIRCam) to study the day-side heat emission spectrum. From the planet. “If it has an atmosphere, Webb has the sensitivity and the wavelength range to detect it and identify its components.”

An illustration of the James Webb Telescope armed and ready to observe space

Photo: Disclosure / NASA

Another possible explanation is what sparked the tweet: 55 Cancri e may not always be locked in the same position, but rather rotates on its axis with slow cycles of day and night. This is what happens to Mercury, the planet closest to the sun in our solar system, which completes three revolutions every two around our star.

In this scenario, the surface will heat up, melt, and even evaporate during the day. At night, the steam cools and condenses to form a lava shower. The droplets will return to their solid form when they hit the ground.

“This may explain why the hotter part of the planet has been displaced,” explains Alexis Brandecker, a researcher at Stockholm University who leads another team studying the planet. “Just like on Earth, it will take time for the surface to heat up. The hottest time of the day will be in the afternoon, not noon.”

Brandeker’s team plans to test this hypothesis using the James Webb camera NIRCam to measure the temperature of the bright side of an exoplanet over four different orbits. If it were like Mercury, then each hemisphere would be observed twice. Thus, scientists will be able to detect the temperature differences between the two hemispheres.

Super Earth, without lava

lhs - NASA / JPL-Caltech / R. Hurt (IPAC) - NASA / JPL-Caltech / R. Hurt (IPAC)

Artistic drawing of LHS 3844 b, a rocky, airless planet that James Webb will investigate

Photo: NASA/JPL-Caltech/R. Hurt (IPAC)

Less impressive than a planet raining lava is another giant Earth that NASA will be looking for. LHS 3844 b is cooler, so its rocky surface must be solid. The difference is that there is probably no air there.

Previous observations showed that this exoplanet, discovered in 2019 and located 49 light-years from Earth, does not appear to have an atmosphere — or at least not one that is dense enough to be detected by our telescopes.

For NASA, this is an advantage: it allows a clearer study of its rocky surface. Laura Kreidberg of the Max Planck Institute for Astronomy in Germany will use the James Webb mid-infrared (MIRI) instrument to analyze the LHS 3844b-day TEM.

Then she plans to compare the results with a spectrophotometer for known rocks such as basalt and granite to see what type of rock is on the surface of LHS 3844b. If the planet is volcanically active, the experiment may also reveal traces of volcanic gases there.

why does it matter?

Of the more than 5,000 confirmed exoplanets in the galaxy, with the most diverse characteristics and compositions, why did NASA decide to study these two soon?

Rocky planets like LHS 3844 b and 55 Cancri e are hard-to-find gas giants, about which we know a lot. Also, “superplanets” like these could give us more clues about the composition of our planet.

“They will give us fascinating new perspectives on Earth-like planets in general, helping us see what early Earths would have looked like when it was as hot as these planets are today,” Kreidberg told NASA.

The study is also a way to test the James Webb Telescope, which only recently completed its alignment and was ready to image the universe.