Using space telescope to observe solar eclipse creates conditions for future telescope to measure the atmosphere of exoplanets in transit system. These atmospheres may contain chemicals of interest to astrobiology (that is, the study and search for life). Although a large number of such ground observations have been made before, this is the first time to capture a total lunar eclipse with ultraviolet wavelengths and space telescopes. Hubble detected a strong spectral fingerprint of ozone, which absorbed some sunlight. Ozone is very important to life because it is the source of the protective layer of the earth's atmosphere.
On the earth, billions of years of photosynthesis have caused high oxygen content and thick ozone layer on the earth. This is one of the reasons why scientists think that ozone or oxygen may be a sign of life on another planet and call it a biological feature. Alison Youngblood, the principal researcher of the Atmospheric and Space Physics Laboratory in Boulder, Colorado, and the principal researcher of the Hubble Telescope, explained: It is significant to discover ozone because it is a photochemical by-product of molecular oxygen, which itself is a by-product of life.
Although ozone has been detected in the earth's atmosphere during the eclipse, the observation and research of Hubble telescope represents the strongest detection of this molecule so far, because ozone (measured from space and not interfered by other chemicals in the earth's atmosphere) absorbs ultraviolet light so strongly. Hubble telescope recorded that during the solar eclipse from 20 191October 20th to1October 20th, ozone absorbed part of the solar ultraviolet radiation passing through the edge of the earth's atmosphere.
During the eclipse, several other ground-based telescopes also made spectral observations at other wavelengths, looking for more atmospheric components on the earth, such as oxygen and methane. One of the main goals of NASA is to identify planets that may support life. However, if we see a habitable or habitable planet, how do we know whether it is habitable or habitable? If astronomers mastered the technology of describing the atmosphere of exoplanets, what would they look like?
This is why it is very important to develop the spectral model of the earth as a template for the classification of the atmosphere of extrasolar planets. If the alien world passes through the surface of its parent star, the atmosphere of some extrasolar planets can be detected. This event is called transit. During the transit, starlight passes through the atmosphere of the backlit exoplanet (if viewed closely, the outline of the planet looks like a thin and luminous "halo" caused by the illuminated atmosphere, just like looking at the earth from space).
Chemicals in the atmosphere will filter out starlight of certain colors (wavelengths), thus leaving obvious features. Astronomers using the Hubble telescope pioneered the technology of detecting exoplanets. This is particularly noteworthy because the Hubble telescope did not find planets outside the solar system when it was launched in 1990, and the space observatory was not originally designed for such experiments. The discovery of ozone in the sky of exoplanets does not guarantee the existence of life on their surfaces. In addition to ozone, other spectral features are needed to conclude that there is life on the planet, and these features may not be visible under ultraviolet light.
On the earth, when the oxygen in the earth's atmosphere is irradiated by strong ultraviolet rays, it will naturally form ozone. Ozone forms a blanket around the earth to protect the earth from strong ultraviolet rays. The study's co-author, Giada Arney of the Goddard Space Flight Center of the National Aeronautics and Space Administration (NASA), said: Photosynthesis is probably the most efficient metabolism that can evolve on any planet because it is driven by sunlight energy and uses a lot of elements, such as water and carbon dioxide.
These essential components should be common on livable planets, and the seasonal variation of ozone signal may also indicate the seasonal biological production of oxygen, just like the growing season of plants on earth. However, when nitrogen and oxygen are exposed to sunlight, ozone can also be produced in the absence of life. In order to increase the confidence that a given biological feature is indeed produced by life, astronomers must look for the combination of biological features. Multi-wavelength combination is necessary because each of many biological features is more easily detected at wavelengths specific to these features.
Astronomers must also consider the development stage of planets when observing young stars with young planets. If we want to detect the oxygen or ozone of the planet similar to the early earth, the spectral characteristics of optical and infrared light are not strong enough when there is less oxygen in the planetary atmosphere. It is considered that before the Mesoproterozoic geological period (about 2 billion to 700 million years ago), the ozone concentration of the earth was very low, when photosynthesis promoted the accumulation of oxygen and ozone in the atmosphere, reaching the present level.
However, because ozone has very strong ultraviolet characteristics, it is desirable to detect a small amount of ozone. Therefore, ultraviolet light may be the best wavelength to detect photosynthetic life on exoplanets under hypoxia. The James Webb Space Telescope, which will be launched by NASA in the future, can make similar measurements under infrared light, and it is possible to detect methane and oxygen in the atmosphere of exoplanets. The Webb Space Telescope is currently scheduled to be launched in 20021year. Let's look forward to the future astronomical discoveries!