Escape velocity I - also referred to as circular velocity, is the speed that must be given to a body to enter Earth orbit. Correspondingly, escape velocity II - is the speed that must be given to a body to leave the Earth completely. III escape velocity - is the velocity that must be given to a body for it to leave the solar system. IV escape velocity - this is the velocity that must be given to a body to leave our Galaxy. ¹⁾

The collision of the two galaxy clusters produced a giant shock wave which, due to the gas pressure, formed a cone-shaped like a bullet, hence the name: Bullet cluster. Dark matter was detected indirectly - by comparing the spatial distribution of gravitational lensing magnitudes with that of ordinary matter, identified with X-ray sources. ²⁾

The Moon's ground reflects more light toward its source than in other directions. This property is rare on Earth, but quite common among rocky celestial bodies. ³⁾

The Lich (PSR 1257+12) is a pulsar in the constellation Virgo around which orbit the first extrasolar planets discovered by Alexander Wolszczan. The proper name for the star Lich was chosen in a public contest. It is derived from the lyre, a fictional undead creature capable of controlling other undead through magic. It is a reference to a pulsar, which is a star that has “died” but still shines. ⁴⁾

Geochemical maps of the Moon's surface show that its crust contains large amounts of anorthositic rocks, which agrees with the theory of the former existence of an ocean of magma. From an elemental point of view, it consists primarily of oxygen 43%, silicon 21%, iron 9%, calcium 9%, and aluminum 10%. ⁵⁾