[▲ Movement of Mercury captured by the Extreme Ultraviolet Imager (EUI) of the solar probe “Solar Orbiter” (movie)]
(Credit: ESA & NASA/Solar Orbiter/EUI Team)
This is using the data acquired on January 3, 2023 by the “Extreme Ultraviolet Imager (EUI)” installed in the European Space Agency (ESA) solar probe “Solar Orbiter”. A short video created. Can you see the black shadow moving from the center to the right against the background of the solar atmosphere captured by EUI?
The identity of the shadow is Mercury, which orbits the Sun at an average distance of about 0.39 AU (about 58 million km). When Mercury and Venus, which are inside the Earth’s orbit, pass between the Sun and the Earth, the Earth may observe Mercury and Venus transiting the Sun. On this day, Mercury passed between the “artificial planet” Solar Orbiter and the Sun, so it was possible to observe the passage of Mercury from the Solar Orbiter. The transit of Mercury as seen from the Solar Orbiter was recorded not only by the EUI, but also by the Polarization and Heliseismic Imaging Instrument (PHI).
[▲ An animation image of Mercury transiting the sun captured by the Solar Orbiter’s Polarization and Heliseismic Imager (PHI) (Credit: ESA & NASA/Solar Orbiter/PHI Team)]
Transit refers to when Mercury or Venus crosses in front of the Sun, but the general phenomenon in which another celestial body crosses in front of another celestial body is called a transit, and it is a powerful tool for finding extrasolar planets. used as one of the means.
It is easy to understand from the animation image of PHI posted earlier, but when the transit occurs, the celestial body that crosses the front partially hides the distant celestial body. If the celestial body to be hidden is a planet and the celestial body to be hidden is a fixed star, the brightness of the star will be slightly darkened by the amount hidden by the planet. will be repeated many times in the same cycle. High-precision observations of planetary transit cycles and stellar light curves (curves that show the luminosity of celestial bodies that change over time) can indirectly provide information such as the planet’s orbital period, diameter, and the presence or absence of an atmosphere. You can get it.
This kind of observation method is called the “transit method”, and includes NASA’s space telescope “Kepler” (operation ended in 2018), exoplanet exploration satellite “TESS”, ESA’s space telescope ” Keops” is also used.
[▲ A video showing how the brightness of a star changes due to the transit of an exoplanet]
(Credit: ESO/L. road)
Source
- Image Credit: ESA, NASA, Solar Orbiter/EUI Team, Solar Orbiter/PHI Team
- ESA – Mercury’s black disc helps sharpen Solar Orbiter’s view
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