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Transit of Venus
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and the Earth, obscuring a small portion of the Sun's ... > more -
Voyager program
The Voyager program consisted of a pair of unmanned scientific probes, Voyager 1 and Voyager 2, launched in 1977. They were sent to study Jupiter and Saturn, using an advantageous planetary alignment ... > more -
Rocket engine
A rocket engine is a reaction engine that can be used for spacecraft propulsion as well as terrestrial uses, such as missiles. Rocket engines take their reaction mass from within the vehicle and form ... > more -
Comet Hale-Bopp
Comet Hale-Bopp was probably the most widely observed comet of the 20th century, and one of the brightest seen for many decades. It was visible to the naked eye for a record 18 months, twice as long ... > more -
Near-Earth object
Near-Earth objects (NEO) are asteroids, comets and large meteoroids whose orbit intersects Earth's orbit and which may therefore pose a collision danger. Due to their size and proximity, NEOs are ... > more -
Alpha Centauri
Alpha Centauri (α Cen / α Centauri) is the brightest star system (a triple star system) in the southern constellation of Centaurus, and contains the fourth brightest star in the night ... > more -
Titan (moon)
Titan, or Saturn VI, is the largest moon of Saturn and the second largest moon in the solar system, after Jupiter's moon Ganymede. It is roughly 50% larger than Earth's moon by diameter, and is ... > more -
Precession of the equinoxes
The precession of the equinoxes refers to the precession of Earth's axis of rotation with respect to inertial space. The precession of the equinoxes is caused by the differential gravitational forces ... > more
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