NASA released the James B. The Webb Space Telescope's first direct image of an exoplanet HIP 65426B, which is 356 light-years from Earth.
How did Webb image exoplanets, which usually don't emit light and can't be seen directly with telescopes, so they're hard to spot?
HIP 65426B is the first exoplanet photographed by the Webb Telescope. What's so special about it? Is it suitable for human habitation?
The Universe is vast, empty, stars and the distances between stars are often dozens of hundreds of light years away. In the distance, the most become dim stars, only some massive stars with the naked eye to see closer stars, and planets itself does not shine the light of the stars will reflect light of the planet to cover living, searching for extrasolar planets is difficult.
But we need to find extraterrestrial intelligence, and we need to find a second home for humanity, so exoplanet observation is the only way to the sea of stars.
The most common method used to determine the existence of planets near stars is the transit method.
When a planet passes around a star, it blocks out some of the star's light, making it less bright. Continuous observation after a period of time, if the change of brightness is regular periodic, which means there is likely to be a planet around stars around it to run, but stars are very bright, sometimes even with planetary transits, also will be submerged in the halo of stars, this is where the space satellite interference to eliminate stars powerful halo, to discover the planet.
The transit method, though simple and common, has some limitations: it can only see the planets of stars in the same plane as Earth.
When the transit method is inapplicable, one can also judge whether there is a small displacement of the stars' planets. In the solar system, the sun's gravity eight planets, let the revolution of the planets around it periodically if the planet's mass is big enough, its gravity will also affect the sun, let the sun is a very small orbit around the planet.
When two celestial bodies orbit each other, the spectrum of the star is shifted by the Doppler frequency, which allows scientists to detect the presence of planets around the star by observing the faint displacement over a long period of time.
These two methods may seem cumbersome, but they are also the simplest and most direct way to find exoplanets. If they are so difficult to find, how can Webb image HIP 65426B directly?
HIP 65426B was first spotted by the European Observatory's Very Large Telescope in Chile in 2017, but when trying to learn more about it, infrared light from the planet was blocked by Earth's atmosphere, preventing further details.
The webb telescope is located on the second day (elm) back light, the light of the sun by the earth keeps out here, the webb telescope can is not affected by the sun, more important is the webb telescope aboard the extreme sensitive infrared detector (MIRI), MIRI is the main force of weber imaging, its working temperature reached less than 7 degrees kelvin (226 ℃ below zero).
At this temperature, the effect of infrared light on observation can be greatly reduced. Because a distant galaxy's light is so faint, its own infrared light would drown out the object if the instrument were kept at its normal temperature, just as it would be hard to spot a firefly under a searchlight.
On top of that, the image is also thanks to the coronagraph that Webb was onboard. As we mentioned above, the bright light from a star, like HIP 65426b, is 10,000 times stronger, making it almost impossible to see it directly under normal circumstances.
But HIP 65426b is 100 times closer to its parent star than the sun, which helps scientists identify it in the image, and the coronagraph blocks out distant stars, reducing glare.
With all this fuss, what's the planet like?
In this image, the white star is the parent star HIP 65426, which is obscured by the coronagna. The yellow-orange spot is HIP 65426b, which is 356 light-years away. It orbits its parent star about 100 times farther than Earth is from the Sun, making it take a full 630 years to orbit its parent star.
We live on a planet that is 4.5 billion years old, but HIP 65426b is only 14 million years old, so it is a very young planet. The planet has not cooled yet, and the heat from its formation is still playing out, so it is extremely hot and bright.
Scientists estimate that HIP 65426b has a surface temperature of at least 900 degrees Celsius, compared to 427 degrees Celsius for Mercury, the solar system's closest neighbor to the sun.
Unlike Earth, HIP 65426b is a gaseous planet, similar to Jupiter, and although its surface features are not visible in the image, scientists think it may look like Jupiter with cloud bands caused by changes in temperature and composition, as well as spots in its atmosphere caused by storms or whirlpools.
So HIP 65426b is clearly not suitable for any life, but that's not the main point of Webb observing it. With the first direct images of exoplanets, there will be more to come, and the Webb Telescope's journey to the stars is just beginning.