Best Leo

CORONA was a highly classified United States military reconnaissance satellite program developed by the CIA and the Air Force. Operating from 1959 to 1972 under the cover name Discoverer, it became America's first operational space photoreconnaissance system. The satellites used a panoramic camera s...

The Vostok 1 mission represents a pivotal moment in space exploration history. Launched by the Soviet Union in April 1961, it involved Yuri Gagarin becoming the first human to achieve orbit around Earth. This single flight demonstrated the feasibility of crewed space travel and established key techn...

The Mercury-Atlas 6 mission involved astronaut John Glenn orbiting Earth in 1962. This was the United States’ initial crewed journey into space and a successful foray into Low Earth Orbit (LEO). The flight demonstrated American capabilities in manned orbital spaceflight and provided valuable data fo...

The KH-9 Hexagon was a series of large photoreconnaissance satellites operated by the US National Reconnaissance Office (NRO) from 1971 to 1986. Often referred to as "Big Bird," it combined high-resolution mapping and surveillance photography into a single platform. The satellite utilized a film-ret...

Regulus, designated Alpha Leonis, is the brightest star in the northern celestial hemisphere constellation of Leo. It is a multiple-star system located roughly 79 light-years from Earth, with its primary component being a hot, blue-white main-sequence star. This primary star rotates at an exceptiona...

China Space Station (Tiangong) is China's permanently crewed modular orbital station, with its core Tianhe module launched in 2021, representing China's first long-term human presence in low Earth orbit.

The Salyut 6 was a Soviet-built orbital station operated between 1977 and 1986. Launched into Low Earth Orbit, it served as a platform for extended crewed space missions. Its two docking ports facilitated the arrival of resupply spacecraft like Progress and allowed cosmonauts to conduct scientific r...

OSCAR-1 was the first amateur-built satellite to reach orbit, launched on December 12, 1961 as a secondary payload aboard a Thor-Agena rocket from Vandenberg Air Force Base. Built by a group of radio amateurs in California, it transmitted a continuous Morse code beacon on 144.983 MHz for approximate...

UARS (Upper Atmosphere Research Satellite) was a NASA satellite deployed from Space Shuttle Discovery during the STS-48 mission in September 1991 into a 57-degree inclination low Earth orbit. It carried ten instruments to measure trace gases, winds, and energy input throughout the stratosphere, meso...

SORCE (Solar Radiation and Climate Experiment) was a NASA satellite launched on January 25, 2003 aboard a Pegasus XL rocket into a 40-degree inclination low Earth orbit. It carried four instruments, including the Total Irradiance Monitor (TIM) and Spectral Irradiance Monitor (SIM), which measured bo...

LEO.org is a German online dictionary and language-learning service whose origins date to a project at the Technical University of Munich in the 1990s. It is particularly known for its German-English dictionary and also provides several other bilingual dictionaries, pronunciation recordings, verb ta...

Lacrosse 1, designated USA-31, was the first operational synthetic aperture radar (SAR) reconnaissance satellite operated by the United States National Reconnaissance Office. It was launched into low Earth orbit aboard the Space Shuttle Atlantis during the STS-27 mission in December 1988. The spacec...

The Earth Radiation Budget Satellite (ERBS) was a NASA scientific spacecraft launched from the Space Shuttle Challenger in October 1984. Designed to investigate how energy from the Sun is absorbed and radiated by Earth's atmosphere, it carried three primary instruments including the Stratospheric Ae...

The Voskhod 2 mission represents a pivotal moment in space exploration. Launched by the Soviet Union in 1965, it achieved the historic first extravehicular activity (EVA) undertaken by Alexei Leonov. Leonov’s spacewalk outside the Voskhod spacecraft demonstrated unprecedented technological capabili...

AO-7 (OSCAR-7) is an amateur radio satellite constructed by volunteers and launched into low Earth orbit by the Radio Amateur Satellite Corporation (AMSAT) in 1974. After its batteries failed in 1981, the satellite ceased transmissions and was presumed permanently lost. However, it unexpectedly resu...

COSMIC-2 is a constellation of six satellites developed jointly by NOAA and Taiwan's NSPO, launched on June 25, 2019 aboard a SpaceX Falcon Heavy. Each satellite uses GPS radio occultation to profile atmospheric temperature, pressure, water vapor, and electron density, producing thousands of daily m...

Algieba, designated Gamma Leonis, is a prominent binary star system located in the zodiac constellation of Leo, approximately 126 light-years from Earth. The system consists of two evolved giant stars, a K-class orange giant and a G-class yellow giant, that orbit each other over a period of several...

Rohini RS-1 was India's first indigenously built satellite successfully placed in orbit, launched on July 18, 1980 from Sriharikota aboard the SLV-3 rocket developed by ISRO. The 35-kilogram experimental satellite carried a solid-state camera for imaging and operated in low-Earth orbit. With this la...

Shenzhou 5 was the first crewed spaceflight for China's space program, launching on October 15, 2003. The mission carried astronaut Yang Liwei into low Earth orbit, where he completed 14 orbits around the planet over a 21-hour period. This achievement made China the third country in the world to ind...

Gemini 8 was a crewed NASA spaceflight launched on March 16, 1966, as part of the Gemini program. Commanded by Neil Armstrong with pilot David Scott, the mission achieved the first successful docking of two spacecraft in orbit when it rendezvoused with an unmanned Agena target vehicle. Shortly after...

Gliese 436 is an M-type red dwarf in the constellation Leo, approximately 33 light-years from Earth. It hosts Gliese 436 b, a transiting exoplanet with roughly Neptune's size and mass that travels in a close, eccentric orbit. Ultraviolet observations with the Hubble Space Telescope revealed an exten...

IRAS 09371+1212, the Frosty Leo Nebula, is a protoplanetary nebula in Leo distinguished by its unique, crystalline water-ice rich outflow.

The Apollo-Soyuz Test Project was a joint space mission conducted in July 1975 by the United States and the Soviet Union. It marked the first time spacecraft from two different nations docked in orbit, serving as a symbol of diplomatic détente during the Cold War. An American Apollo module successfu...

Gemini 4 was a 1965 crewed spaceflight conducted by NASA as part of the Gemini program. Commanded by James McDivitt with pilot Ed White, the mission successfully executed the first American spacewalk. During the four-day Earth-orbit mission, White spent approximately twenty minutes outside the space...

SAMPEX (Solar Anomalous and Magnetospheric Particle Explorer) was a NASA satellite launched in July 1992 as the first mission in the Small Explorer program. It operated in a low Earth orbit to study the energy spectra and composition of solar energetic particles, galactic cosmic rays, and magnetosph...

The Frosty Leo Nebula, scientifically designated as IRAS 09371+1212, is a bipolar protoplanetary nebula located in the constellation Leo. It represents a brief transitional phase in stellar evolution where a dying star sheds its outer layers before becoming a white dwarf. The nebula is distinguished...

Denebola, designated Beta Leonis, is the second-brightest star in the constellation Leo. Located approximately 36 light-years from Earth, it is an A-type main-sequence star that marks the tail of the celestial lion. Denebola is a confirmed member of the Ursa Major Moving Group, an association of sta...

SO-50, also known as SaudiSat 1C, is an amateur radio satellite launched by Saudi Arabia in 2002. It orbits the Earth in a low-Earth orbit and operates as an FM voice repeater for use by amateur radio operators worldwide. The satellite requires a 67.0 Hz CTCSS tone to activate its transmitter, after...

SAR-Lupe 1 is a reconnaissance satellite operated by the German Armed Forces and launched in 2006. It was the first of five identical spacecraft forming the SAR-Lupe constellation, which provides Germany with independent satellite-based imagery intelligence. The satellites use synthetic aperture rad...