An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists in the observable universe. In astronomy, the terms object and body are often used interchangeably. However, an astronomical body or celestial body is a single, tightly bound, contiguous entity, while an astronomical or celestial …

The International Astronomical Union (IAU; French: Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation. It was founded in 1919 and is based in Paris, France.. The IAU is …

The horizon is the apparent line that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This line divides all viewing directions based on whether it intersects the relevant body's surface or not. The true horizon is a theoretical line, which can only be observed to any degree of accuracy …

Consensus points. The current scientific consensus is that: Earth's climate has warmed significantly since the late 1800s. Human activities (primarily greenhouse gas emissions) are the primary cause.; Continuing emissions will increase the likelihood and severity of global effects.; People and nations can act individually and collectively to slow the pace of global warming, …

The astronomical unit of mass is the solar mass. The symbol M ☉ is often used to refer to this unit. The solar mass (M ☉), 1.988 92 × 10 30 kg, is a standard way to express mass in astronomy, used to describe the masses of other stars and galaxies.It is equal to the mass of the Sun, about 333 000 times the mass of the Earth or 1 048 times the mass of Jupiter.

Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself.In other words, if the axis of rotation of a body is itself rotating about a second axis, that body is said to be precessing about the second axis.

Apparent magnitude (m) is a measure of the brightness of a star or other astronomical object observed from Earth.An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's light caused by interstellar dust along the line of sight to the observer.. The word magnitude in astronomy, unless stated otherwise, …

The Royal Astronomical Society (RAS) is a learned society and charity that encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. Its headquarters are in Burlington House, on Piccadilly in London.The society has over 4,000 members ("Fellows"), most of them professional researchers or postgraduate students.

A planet is a large, rounded astronomical body that is neither a star nor its remnant.The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk.Planets grow in this disk by the gradual accumulation of material driven by gravity, a …

In physics, the n-body problem is the problem of predicting the individual motions of a group of celestial objects interacting with each other gravitationally. Solving this problem has been motivated by the desire to understand the motions of the Sun, Moon, planets, and visible stars.In the 20th century, understanding the dynamics of globular cluster star systems became an …