Charon (moon)Largest natural satellite of PlutoCharon ( or ), formal designation (134340) Pluto I, is the largest of the five known natural satellites of the dwarf planetPluto. It has a mean radius of 606 km (377 mi). Charon is a planetary-mass moon and the sixth-largest known trans-Neptunian object after Pluto, Eris, Haumea, Makemake, and Gonggong.
LibrationIn lunar astronomy, libration is the cyclic variation in the apparent position of the Moon that is perceived by observers on the Earth and caused by changes between the orbital and rotational planes of the Moon. It causes an observer to see slightly different hemispheres of the surface at different times. It is similar in both cause and effect to the changes in the Moon's apparent size because of changes in distance.
Dysnomia (moon)Dysnomia, formal designation (136199) Eris I, is the only known moon of the dwarf planetEris and is the second-largest known moon of a dwarf planet, after Pluto I Charon. It was discovered in September 2005 by Mike Brown and the Laser Guide Star Adaptive Optics (LGSAO) team at the W. M. Keck Observatory.
EarthThird planet from the SunSurface equivalent doserate0.274 μSv/hAbsolute magnitude (H)−3.99AtmosphereSurface pressure101.325 kPa (at sea level)Composition by volume78.084% nitrogen (dry air)20.946% oxygen (dry air)≤1% water vapor (variable)0.9340% argon0.0430% carbon dioxide0.00182% neon0.00052% helium0.00017% methane0.00011% krypton0.00006% hydrogen Source:Earth is the third planet from the Sun and the only astronomical object known to harbor life.
Eris (dwarf planet)Most massive dwarf planetSpectral typeB−V=0.78, V−R=0.45Apparent magnitude18.7Absolute magnitude (H)–1.26Angular diameter34.4±1.4milli-arcsecEris (minor-planet number136199) is the most massive and second-largest-known dwarf planet in the Solar System. It is a trans-Neptunian object (TNO) in the scattered disk and has a high-eccentricity orbit. Eris was discovered in January 2005 by a Palomar Observatory–based team led by Mike Brown and verified later that year.
OrbitIn celestial mechanics, an orbit is the curved trajectory of an object under the influence of an attracting force. Alternatively, it is known as an orbital revolution, because it is a rotation around an axis external to the moving body. Examples for orbits include the trajectory of a planet around a star, a natural satellite around a planet, or an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point.
GravityAttraction of masses and energyThe shapes of two massive galaxies in this image evolved under the effects of gravity.In physics, gravity (from Latin gravitas 'weight'), also known as gravitation or a gravitational interaction, is a fundamental interaction, which may be described as the force that draws material objects towards each other.
MoonNatural satellite orbiting EarthSurface absorbed doserate13.2 μGy/h(during lunar daytime)Surface equivalent doserate57.0 μSv/h(during lunar daytime)Apparent magnitude−2.5 to −12.9−12.74 (mean full moon)Absolute magnitude (H)0.2Angular diameter29.3 to 34.1 arcminutesAtmosphereSurface pressure10 Pa (1 picobar) (day)10 Pa (1 femtobar) (night)Composition by volumeHeArNeNaKHThe Moon is the only natural satellite of Earth.
PlutoLargest dwarf planet in the Solar SystemApparent magnitude13.65 to 16.3 (mean is 15.1)Absolute magnitude (H)−0.55Angular diameter0.06″ to 0.11″AtmosphereSurface pressure1.0 Pa (2015) (9.9×10 atm)Composition by volumeNitrogen, methane, carbon monoxidePluto (minor-planet number134340) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun.
Natural satelliteAstronomical body that orbits a planetThe Moon orbiting around Earth (observed by the Deep Space Climate Observatory)A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, by analogy with the Moon, Earth's natural satellite.
Rotational frequencyRotational frequency, also known as rotational speed or rate of rotation (symbols ν, lowercase Greek nu, and also n), is the frequency of rotation of an object around an axis. Its SI unit is the reciprocal seconds (s); other common units of measurement include the hertz (Hz), cycles per second (cps), and revolutions per minute (rpm). Rotational frequency can be obtained dividing angular frequency, ω, by a full turn (2πradians): ν=ω/(2πrad).
Astronomical objectAn astronomical object, celestial object, stellar object or heavenly object is a naturally occurring physical entity, association, or structure that exists within the universe. In astronomy, the terms object and body are often used interchangeably.*As an Amazon Associate I earn from qualifying purchases.