A large number of stars are not solitary, but belong to systems formed by two or more stars, in which the formation of planets can be difficult due to the absence of stable orbits: the protoplanets would be dragged in either direction by the gravitational influences of the different stars.
Neptune is the fourth planet in terms of size and the eighth in terms of distance to the Sun. The average distance from Neptune to the Sun is 4.5 billion kilometers and its average linear diameter is approximately 49.400 km, that is, about 3.8 times that of Earth. The rotation period is about 16 hours and the sidereal period of revolution is 164.79 years.
Two thousand meters underground, a giant sphere has begun to detect almost invisible particles. These particles, the neutrinos, are extremely abundant in the Universe, but are generally capable of passing through any body. By filling this 12-meter sphere with a rare type of heavy water and surrounding it with light detectors, astrophysicists hope to catch an occasional collision.
Nacre clouds are a phenomenon very similar to iridescent clouds, but they occur at high latitudes. Also known as polar stratospheric clouds or mother of pearl clouds, they can also be seen at night, being in this case called pearly noctilucent clouds. The process of formation of this optical effect is the same as that of iridescent clouds, but occurs at a much greater height.
Before sunrise over the mountains, the sky lit up with different colors. The unexpected light was caused by a group of iridescent clouds, and filmed in early September in Arolla, Wallis, Switzerland. The foreground peak of the image above is Aiguille de la Tsa. Iridescent clouds contain areas of water droplets of almost equal sizes that can therefore diffract sunlight fairly evenly.
Lunar seas Did you know that there are seas not only on Earth, but also on the Moon? And did you know that the seas of the terrestrial satellite are visible to the naked eye, from our planet? But, be careful: that our imagination does not play a trick on us by imagining large areas of salt water, agitated by large and numerous waves on the lunar surface.