Universe questions

The Pinwheel Galaxy ( M101) is a face-on spiral galaxy distanced 21 million light-years away from Earth in the constellation Ursa Major. M101 is a large galaxy, with a diameter of 170,000 light-years. By comparison, the Milky Way has a diameter of 258,000 light years. It has around a trillion stars, twice the number in the Milky Way. It has a disk mass on the order of 100 billion solar masses, along with a small central bulge of about 3 billion solar masses.

An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes. This intellect is often referred to as Laplace's demon.

The dwarf planet Pluto has five moons down to a detection limit of about 1 km in diameter. In order of distance from Pluto, they are Charon, Styx, Nix, Kerberos, and Hydra. Charon, the largest of the five moons, is mutually tidally locked with Pluto, and is massive enough that Pluto–Charon is sometimes considered a double dwarf planet.

The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy. The equation was written in 1961 by Frank Drake, not for purposes of quantifying the number of civilizations, but as a way to stimulate scientific dialogue at the first scientific meeting on the search for extraterrestrial intelligence (SETI). The equation summarizes the main concepts which scientists must contemplate when considering the question of other radio-communicative life.

Most physicists believe that faster than light particles cannot exist because they are not consistent with the known laws of physics. If such particles did exist, they could be used to send signals faster than light, which would lead to violations of causality. Despite those arguments, experiments have been conducted to search for them, but no compelling evidence has been found.

The distance is exactly 92.96 million mi. It varies every season, but this is the average distance.

Cygnus is a northern constellation lying on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. It is one of the most recognizable constellations of the northern summer and autumn. Its brightest star, Deneb, is one of the vertices of the asterism known as the Summer Triangle and forms the 'head' of the neck-less Northern Cross.

The Big Dipper, or the Plough, is an asterism consisting of seven bright stars of the constellation Ursa Major. Four define a "bowl" or "body" and three define a "handle" or "head". It is recognized as a distinct grouping in many cultures.

In 1866, after the perihelion passage of Swift-Tuttle in 1862, the Italian astronomer Giovanni Virginio Schiaparelli discovered the link between meteor showers and comets. His findings put new light on a subject, and changed the approach of astronomers to comets.

Giotto became the first spacecraft to make close up observations of a comet. On 13 March 1986, the mission succeeded in approaching Halley's nucleus at a distance of 596 kilometers. It was also the first spacecraft to return from interplanetary space and perform an Earth swing by. The spacecraft was named after the Early Italian Renaissance painter Giotto di Bondone.