Portal:Astronomy

Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond Earth's atmosphere. Cosmology is the branch of astronomy that studies the universe as a whole.

Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Egyptians, Babylonians, Greeks, Indians, Chinese, Maya, and many ancient indigenous peoples of the Americas. In the past, astronomy included disciplines as diverse as astrometry, celestial navigation, observational astronomy, and the making of calendars.

Astronomy is one of the few sciences in which amateurs play an active role. This is especially true for the discovery and observation of transient events. Amateur astronomers have helped with many important discoveries, such as finding new comets. (Full article...)

Grayscale image of Umbriel from Voyager 2, January 1986. Umbriel's surface is heavily battered; the bright crater Wunda can be seen at the top of the image near the moon's equator

Umbriel (/ˈʌmbriəl/) is the third-largest moon of Uranus. It was discovered on October 24, 1851, by William Lassell at the same time as neighboring moon Ariel. It was named after a character in Alexander Pope's 1712 poem The Rape of the Lock. Umbriel consists mainly of ice with a substantial fraction of rock, and may be differentiated into a rocky core and an icy mantle. The surface is the darkest among Uranian moons and appears to have been shaped primarily by impacts, However, the presence of canyons suggests early internal processes. The moon may have undergone an early endogenically driven resurfacing event that obliterated its older surface.

Covered by numerous impact craters reaching 210 km (130 mi) in diameter, Umbriel is the second-most heavily cratered satellite of Uranus after Oberon. The most prominent surface feature is a ring of bright material on the floor of Wunda crater. This moon, like all regular moons of Uranus, probably formed from an accretion disk that surrounded the planet just after its formation. Umbriel has been studied up close only once, by the spacecraft Voyager 2 in January 1986. It took several images of Umbriel, which allowed mapping of about 40% of the moon's surface. (Full article...)

• ... that Jerry Nelson is the principal designer and project scientist for the Keck telescopes?
• ... that five supernovae have been found in the Messier 100 spiral galaxy?
• ... that the Antlia Dwarf galaxy may have distorted the shape of its neighbour NGC 3109 one billion years ago?
• ... that AP Columbae, the closest young star known, formed after the dinosaurs became extinct?
• ... that a planet was discovered around the star MOA-2009-BLG-387L after it eclipsed a background star, refracting the star's light in a process called gravitational microlensing?

• ... that novelist Hal Clement created the planet Mesklin in 1953 based on the real-world suspected detection of an extrasolar planet?
• ... that the majority of extrasolar planets in fiction are inhabited by native species?
• ... that Na drugą planetę, published in 1895 as one of the earliest Polish science-fiction novels, was later criticized by communist-era censors for its perceived "adoration for America"?
• ... that in many works of fiction, the asteroid belt is the remnants of a destroyed planet?
• ... that examples of artificial planets in science fiction include Riverworld, the Well World, and the Death Star?
• ... that the Springfield Science Museum is home to the oldest operating projection planetarium in the United States?

Hubble Space Telescope image of NGC 6052, discovered on 11 June 1784 by William Herschel. The two components of NGC 6052 are designated NGC 6052A and NGC 6052B are attracted by each other's gravity, have collided and are interacting with each other.

10 December 2025 – Brazil–China relations

Brazil and China begin constructing a joint laboratory for radio astronomic technology with the Federal University of Campina Grande and the Federal University of Paraíba to support space research as both countries work on the BINGO radio telescope. (Reuters)

• 5 February 1974 – Mariner 10 becomes the first spacecraft to use a gravity assist when it flies by Venus in order to reach Mercury
• 5 February 2002 – HESSI (High Energy Solar Spectroscopic Imager) solar flare observatory is launched on a mission to explore the physics of particle acceleration and energy release in solar flares
• 10 February 2002 – Solar Orbiter is launched to perform detailed measurements of the inner heliosphere and nascent solar wind, and perform close observations of the polar regions of the Sun
• 15 February 1845 – The Leviathan of Parsonstown, the world's largest telescope from 1845 to 1917, sees first light
• 18 February 1930 – 23-year-old astronomer Clyde Tombaugh discovers Pluto by using a blink comparator on photographs he took in the previous month at Lowell Observatory
• 25 February 2002 – Mariner 6 is launched to study the surface and atmosphere of Mars during close flybys