2019
November
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Could an Earth-like planet also survive in an eccentric solar system?

HR5183 is a yellow dwarf star, not very different from our own Sun and located about 103 light-years from Earth. After more than 20 years of observation, astronomers finally found a planet, of about three times Jupiter’s mass, orbiting the star this past summer. Why did it take so long? The planet, HR5183 b, needs 75 years to complete one orbit around its star. Therefore, the period at which it affects the light curve of its star is also correspondingly long.

But what surprised the astronomers even more was the planet’s unusual orbit. HR5183 b comes about as close to its star as Jupiter’s distance to the Sun and then swings out to a distance far beyond that of Neptune’s orbit. Such an eccentric orbit had previously been observed only very rarely.

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New organic molecules discovered on Saturn’s moon Enceladus

Two years ago, the Cassini probe was sent plummeting into Saturn to its fiery demise – but researchers are still finding new discoveries in the data it sent back. Now, scientists from the Free University Berlin have reported findings from the CDA, the “Cosmic Dust Analyzer,” which was on board Cassini. This instrument was developed in Germany and was designed to study very small particles.

The CDA could detect particles with a velocity of 5 kilometers per second and a mass of only 1013 grams (a ten-millionth of a millionth of a gram, which corresponds to a size of two-thousands of a millimeter). In addition to the particle velocity and particle size (10 nanometers to 100 micrometers), it also determined the electrical charge of the particles and their basic composition.

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Will our Solar System soon have its sixth dwarf planet?

According to the definition of the International Astronomical Union (IAU), dwarf planets are celestial bodies that do indeed have the round shape of a planet, but do not have sufficient mass to dominate the area around their distance to the Sun. The most well-known example of a dwarf planet is surely Pluto (with a diameter of 2400 kilometers (1490 miles)). Eris, Makemake, and Haumea are three other dwarf planets orbiting in the outer regions of our Solar System. At 950 kilometers (590 miles), Ceres is the largest object in the Asteroid Belt and simultaneously the smallest dwarf planet.

But maybe not for much longer, because the asteroid Hygiea also appears to be approximately spherical. The asteroid discovered by Annibale de Gasparis on April 12, 1849 in Naples was named after Hygieia, the daughter of the god Asclepios from Greek mythology. It is only the fourth largest object in the Asteroid Belt. However, differently than the somewhat larger asteroids, Vesta and Pallas, it actually appears to be spherical, as observations with the SPHERE instrument of the Very Large Telescope of the European Southern Observatory, ESO, have shown.

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