Escape velocity I, also referred to as circular velocity, is the speed that a body must reach to enter Earth's orbit. Correspondingly, escape velocity II is the speed that must be reached for a body to leave the Earth's orbit completely. Escape velocity III is the velocity a body must reach for it to leave the solar system, and escape velocity IV is the velocity that a body must reach to leave our galaxy. ¹⁾

The collision of two galaxy clusters produced a gigantic shock wave which, due to the gas pressure, formed a bullet-shaped cone, 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⁾