A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Iapetus
IBEX (Interstellar Boundary Explorer)
IBSS (Infrared Background Signature Survey)
ibuprofen
IC 10
IC 10 X-1 (stellar black hole)
IC 349 (Barnard's Merope Nebula)
IC 410
IC 59 (nebula near Gamma Cassiopeiae)
Icarus
ICE (International Cometary Explorer)
ice
ice ages
ice worm
iceberg
icebreaker
IceCube
Iceland spar
ICESat (Ice, Cloud, and Land Elevation Satellite)
ice-sheet
ice-water interface station
ichthyosaur
Ichthyostega
ICO
icosahedron
Icosian Game
Ida
IDCSP (Initial Defense Communications Satellite Program)
ideal gas
ideal gas law
ideal rocket
idealism
idiopathic pulmonary fibrosis
idiopathic thrombocytopenic purpura
idocrase
IEH (International Extreme Ultraviolet Hitchhiker)
igneous age
igneous rock
ignitron
IGY (International Geophysical Year)
Ikeya-Seki, Comet (C/1965 S1)
Ikonos
iliac arteries
ileum
ilium
illicit cargo
illuminance
illusion
ILLUSIONS AND IMPOSSIBLE FIGURES
ilmenite
image
IMAGE (Imager for Magnetopause-to-Aurora Global Exploration)
image intensifier
image processing
image tube
imaginary number
imago
imide
immune system
immunity
immunoglobulin
immunosuppressant drug
immunotherapy
IMP (Interplanetary Monitoring Platform)
impact basin
impact crater
impact feature
impact melt
impedance
impetigo
implantable cardioverter defibrillator
implosion
impossibilities in mathematics
impossible figure
impossible motion
impossible trident
imprinting
impulse
inbreeding
incandescence
inch
inclination
inclined plane
inclinometer
incubation
incubation period
incubator
indehiscent
independent assortment
indeterminate equations
INDIA IN SPACE
Indian astronomy
Indian launch vehicles
indicator
indium
inductance
induction (electromagnetic)
induction coil
induction motor
induction ring
induction sail
inductor
Indus (constellation)
industrial chemistry
INDUSTRIAL CHEMISTRY
Industrial Revolution
inelastic collision
inequality
inertia
inertia wheel
inertial force
inertial guidance
inertial reference frame
inertial stabilization
inertial upper stage
infall velocity
infectious disease
inferior thyroid artery
inferior vena cava
infinite series
infinitesimal
infinity
inflammation
Inflatable Antenna Experiment
inflationary model
inflection
inflorescence
influenza
information theory
infrared
infrared astronomy
Infrared Astronomy Satellite (IRAS)
infrared cirrus
infrared galaxy
Infrared Space Observatory (ISO)
Infra-Red Telescope Facility (IRTF)
infrasound
inhibitor
injection
ink
inlier
Inmarsat
inner ear
Innes, Robert Thorburn Ayton (1861–1933)
Innisfree meteorite
innominate
innominate artery
innominate veins
inorganic chemistry
INORGANIC CHEMISTRY
inscription
insect
insect senses
Insectivora
insects that bite and sting
inselberg
insertion
InSight (Mars spacecraft)
insomnia
Inspector
instability
instability strip
instantaneous bandwidth
instrument landing system
instrumentalism
INSTRUMENTATION
insulin
integer
integral
INTEGRAL (International Gamma-ray Astrophysics Laboratory)
Integral Sign Galaxy (UGC 3697)
Integrated Truss Structure
integration
integumentary system
intelligence, artificial
intelligence, nature of
intelligent dinosaurs
Intelsat (International Telecommunications Satellite Organization)
intensity
interacting binary
Interamnia (asteroid)
Interbol
intercalation compound
intercept
Intercosmos
intercostal muscles
interesting number
interference
interferometer
interferon
intergalactic absorption
intergalactic medium
Intergalactic Wanderer (NGC 2419)
intermediate filament
intermediate population star
internal carotid artery
internal combustion engine
internal conversion
internal energy
internal jugular vein
internal mammary artery
internal oblique muscle
International Astronautical Federation (IAF)
International Astronomical Union (IAU)
International Atomic Time (TAI)
International Celestial Reference Frame (ICFR)
International Dark-Sky Association
International Date Line
International Geophysical Year (IGY)
International Quiet Sun Years (IQSY)
International Solar Polar Mission
International Space Science Institute
International Space Station (ISS)
International Ultraviolet Explorer (IUE)
interphase
interplanetary communication
interplanetary magnetic field (IMF)
interplanetary medium
interpolate
intersection
INTERSTELLAR AND INTERPLANETARY MATTER
interstellar ark
interstellar asteroid
Interstellar Boundary Explorer (IBEX)
interstellar cloud
interstellar colonization
interstellar communication
interstellar distances
interstellar dust
interstellar erosion
interstellar extinction
interstellar maser
interstellar medium (ISM)
interstellar molecules
interstellar polarization
Interstellar Precursor Mission
interstellar precursor missions
Interstellar Probe
interstellar probes
interstellar propulsion
interstellar radio messages
interstellar ramjet
interstellar travel
interstitial cells
intervertebral disk
intestine
intra-cluster medium
intravenous drip
intrinsic color index
intron
intrusive
intubation
Invaders From Mars
invar
Invasion of the Body Snatchers
inverse
inverse P Cygni profile
inverse-square law
inversion
invertebrate
in-vitro fertilization
involute
inward orbital migration
Io
iodine
ion
ion exchange
ion propulsion
ionic bond
ionic equilibrium
ionic radius
ionization
ionization chamber
ionization front
ionization potential
ionization temperature
ionized layers
ionizing radiation
ionosphere
Iota Horologii
Iota Orionis
IP Pegasi
ipecac
IRAS-Araki-Alcock, Comet (C/1983 H1)
IRFNA (inhibited red fuming nitric acid)
iridescence
iridium (element)
Iridium (satellites)
iris (eye)
Iris (asteroid)
Iris (sounding rocket)
iron
iron meteorite
iron-deficiency anemia
ironstone
irradiance
irradiation
irradiation illusion
irrational number
irregular galaxy
irregular moon
irregular variable
IRS (Indian Remote Sensing satellite)
IRTS (Infrared Telescope in Space)
Irwin, James Benson (1930–1991)
ischium
ISEE (International Sun-Earth Explorer)
Ishango bone
Isidis Planitia
ISIS (International Satellites for Ionospheric Studies)
island
island arc
island birds
Island One
islets of Langerhans
ISM
isobar (meteorology)
isobars (nuclear physics)
isochrone
isoelectronic
isogamy
isogonal conjugate
isomeric transition
isomerism
isomers
isometry
isomorphism
isoperimetric inequality
isopod
isoprene
isosceles
isostasy
isotherm
isothermal process
isotomic conjugate
isotopes
isotopic spin
isotropic
isovolume problem
Israel in space
ISS (Ionospheric Sounding Satellite)
isthmus
It Came From Outer Space
iteration
Itokawa (asteroid)
ITOS (Improved TIROS Operating System)
IUS (inertial upper stage)
Ivuna meteorite
Izar (Epsilon Bootis)