K star
K-1 (reusable space vehicle)
K40506A
Kaba meteorite
Kagoshima Space Center
kakangariite
Kakeya needle problem
Kakehashi (a.k.a COMETS)
Kakkab (Alpha Lupi)
Kaliningrad
Kaluza-Klein theory
kamacite
kampyle of Eudoxus
Kant, Immanuel (1724-1804)
Kaplan, Joseph (1902-1991)
kappa curve
Kaprekar constant
Kaprekar number
Kapteyn, Jacobus Cornelius (1851-1922)
Kapteyn's Star (HD 33793)
Kapustin Yar
Kardashev, Nikolai S. (1932-)
Kardashev civilizations
Karin Cluster
karyotype
Kasner, Edward (1876-1955)
Kaus Australis (Epsilon Sagittarii)
Keck Interferometer
Keck Observatory
Keck Telescopes
Keeler, James Edward (1857-1900)
Keenan’s System (NGC 5216 and NGC 5218)
Keldysh, Mstislav Vsevolodovich (1911-1978)
Kelly, Thomas (1930-2002)
kelvin (K)
Kelvin, Lord (William Thomson) (1824-1907)
Kelvin-Helmholtz contraction
Klemplerer Rosette
Kennedy, John F. (1916-1963)
Kennedy Space Center (KSC)
Kepler, Johannes (1571-1630)
Kepler Mission
Keplerian orbit
Keplerian rotation curve
Keplerian telescope
Kepler-Poinsot solids
Kepler's conjecture
Kepler's equation
Kepler's laws of planetary motion
Kepler’s Star (SN Oph 1604)
keratin
kerogen
kerosene
Kerr black hole
Kerwin, Joseph Peter (1932-)
ketone
ketone bodies
Kettering Bug
Key Hole (KH)
Keyhoe, Donald E. (1897-1988)
Khayyáam, Omar (1048-1122)
Khintchine's constant
Kibalchich, Nikolai Ivanovitch (1854-1881)
kidney
kidney machine
kidney stone
Kiku (ETS, Engineering Test Satellite)
kilogram (kg)
kilohertz (kHz)
kilometer (km)
kiloparsec (kpc)
kinase
kinematics
kinetic energy
kinetic temperature
kinetic theory of gases
kingdom
kings problem
kinship puzzles
Kipp's apparatus
Kirchoff, Gustav Robert (1824-1887)
Kirkman, Thomas Penyngton (1806-1895)
Kirkwood, Daniel (1814-1895)
Kirkwood gaps
Kiruna
kite
Kitt Peak National Observatory (KPNO)
Kitt Peak 12-Meter Telescope
Kittinger, Joseph W. (1928-)
KIWI (nuclear reactor series)
Klass, Philip J.
Klein, Christian Felix (1849-1925)
Klein, Harold P. ("Chuck") (1921-2001)
Kleopatra (minor planet 216)
Klumpke-Roberts, Dorothea (1861-1942)
K-meson
knee
knee disorders
knight's tour
Knoll, Andrew H.
knot
Knuth's up-arrow notation
Koch snowflake
Kochab (Beta Ursae Minoris)
Kodiak Launch Complex
Kohoutek, Comet (C/1973 E1)
Kolmogorov, Andrei Nikolaievich (1903-1987)
Komarov, Vladimir Mikhaylovich (1927-1967)
Korabl-Sputnik
Kordylewski Clouds
Korolev, Sergei Pavlovich (1907-1966)
Koronis family (of asteroids)
Kourou
KPNO
Kraft, Christopher Colombus, Jr. (1924-)
Kramers' law
Kranz, Eugene "Gene" F. (1933-)
Kraus, John D. (1910-2004)
KREEP
Krieger, Robert L. (1916-1990)
Krikalev, Sergei Konstantinovich (1958-)
Kronecker, Leopold (1823-1891)
Krüger 60
Krunichev State Research and Production Space Center
krypton
K-T boundary
Kuiper, Gerard Peter (1905-1973)
Kuiper Airborne Observatory
Kuiper Belt
Kuiper Belt object
Kuiper Belt objects, largest
Kummersdorf
Kupon
Kurchatov, Igor (1902-1960)
Kurzweg, Hermann H. (1908-)
Kwajalein Missile Range
Kyokko