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Letter A

A is for …

NASA’s Picture Dictionary

Check out what A stands for …

Aerodynamics
Aeronautics
Ailerons
Aircraft
Airlock
Altitude
Apollo
Artemis
Asteroid
Astronaut
Astronomer
Astronomy
Atmosphere
Aviation
Axis

Aerodynamics

The study of how air flows around an object.

A picture of colored dye flowing past a model of a plane to test its aerodynamics.
Dryden Flight Research Center ECN 33298-036. Photographed 1985. F-18 water tunnel tests in Flow Visualization Facility. A plastic model of an aircraft is being tested inside a water tunnel. The blue, red and green dyes in the water help NASA see how air moves over the airplane.
NASA/Dryden

Sentences:
NASA studies aerodynamics to make airplanes safer.
Race car drivers study aerodynamics to help make their cars drive faster.

Related Links:
What is Aerodynamics? (Grades K-4)
What is Aerodynamics? (Grades 5-8)

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Aeronautics

The study of flight and the workings of aircraft.

Two men sit at computers while testing an airplane in the background
Engineers test a Navy plane at the flight loads lab at NASA’s Armstrong Flight Research Center in California.
NASA

Sentences:
The first “A” in NASA stands for aeronautics.
One reason NASA studies aeronautics is to learn how to make flight safer.

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Ailerons

Movable flaps on the wings of an airplane that are used to control the plane’s side-to-side movements.

NASA aircraft sits on a runway. The aileron is highlighted
Ailerons cause one wing tip to move up and the other wing tip to move down, helping a plane turn.
NASA

Sentences:
The pilot uses ailerons to turn an airplane to the right or left.
The word “aileron” is French for “little wing.”

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Aircraft

A vehicle that flies through the air.

NASA’s remotely-piloted Ikhana aircraft
NASA’s remotely-piloted Ikhana aircraft, based at the agency’s Armstrong Flight Research Center in Edwards, California, is flown in preparation for its first mission in the National Airspace System without a safety chase aircraft.
NASA

Sentences:
NASA studies aircraft to try to make them safer.
An airplane is a kind of aircraft.

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Airlock

An airtight room with two entrances that allows an astronaut to go on a spacewalk without letting the air out of the spacecraft.

Astronaut wearing a bulky white spacesuit looks out at space from the open hatch of the space station's airlock
Astronaut Chris Cassidy uses the Quest airlock to exit the space station.
NASA

Sentences:
Astronauts get dressed for their spacewalks in an airlock on the space station.
Houses in cold places have an airlock so that cold air doesn’t get into the house.

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Altitude

The height of something above the ground.

A white balloon floats into the sky as three people watch from the snow-covered ground
Scientists use balloons to test the air around Earth. The balloons can go to high altitudes.
NASA

Sentences:
NASA flies experiments on airplanes that fly at high altitudes.
Some mountains have very high altitudes.

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Apollo

The name of the NASA program that took astronauts to the Moon in the 1960s and 1970s, named after a god from Greek mythology.

Apollo 16 Lunar Module Pilot Charles Duke salutes the flag
Apollo 16 Lunar Module Pilot Charles Duke salutes the flag
NASA

Sentences:
The Apollo 11 mission took the first humans to land on the Moon on July 20, 1969.
During the Apollo missions of 1969–1972, 12 American astronauts walked on the Moon.

Related Links:
What Was the Apollo Program? (Grades K-4)
What Was the Apollo Program? (Grades 5-8)

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Artemis

The mission, named after the goddess in Greek mythology, that will take a crew with the first woman and the next man to the Moon.

An image of the Moon with the Artemis insignia and the words "You are the Artemis Generation as a text overlay

Sentences:
The Artemis mission will land astronauts on the Moon in 2024.
NASA has a new rocket and a new spacecraft for Artemis.

Related Link 
What Is the Artemis Program? (Grades K-4)
What Is the Artemis Program? (Grades 5-8)
Forward to the Moon with Artemis Explorer Activities Puzzle Book

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Asteroid

A rocky object in space that can be a few feet wide to several hundred miles wide. Most asteroids in the solar system orbit in a belt between Mars and Jupiter.

Giant asteroid Vesta
Vesta is an asteroid. It has a set of three craters known as the “snowman.”
NASA

Sentences:
NASA’s Dawn spacecraft studies asteroids.
Thousands of asteroids are in orbit around the sun.

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Astronaut

A person trained to travel and work in space.

Astronaut Barbara Morgan posing for her official portrait in an orange suit.
Astronaut Barbara Morgan was NASA’s first Educator Astronaut.
NASA

Sentence:
An astronaut trains a long time on Earth before going into space.

Related Links:
Read About Astronauts

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Astronomer

Someone who studies the planets, stars and space.

A woman holding up one end of a homemade telescope
Amateur astronomer Jane Houston Jones holds up the end of one of her homemade telescopes.
NASA

Sentences:
NASA astronomers discover new things in the universe.
If you want to be an astronomer, you should study science and math in college.

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Astronomy

The study of stars, planets and space.

Type Ia supernova G299.
G299 was left over by a particular class of supernovas called Type Ia. Astronomers think that a Type Ia supernova is a thermonuclear explosion – involving the fusion of elements and release of vast amounts of energy − of a white dwarf star in a tight orbit with a companion star. If the white dwarf’s partner is a typical, Sun-like star, the white dwarf can become unstable and explode as it draws material from its companion. Alternatively, the white dwarf is in orbit with another white dwarf, the two may merge and can trigger an explosion.
NASA/CXC/U.Texas

Sentences:
NASA uses telescopes to study astronomy.
To study astronomy, you might have to stay up late to see the stars.

Related Links:
Astronomy Picture of the Day

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Atmosphere

The layer of gases surrounding a planet.

Colorful view of Earth's atmosphere looking across Earth's surface from the space station
Layers of Earth’s atmosphere are shown in a view looking across Earth’s surface from the International Space Station.
NASA

Sentences:
Earth’s atmosphere protects life on the planet.
Earth’s atmosphere has five layers.

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Aviation

The design, building, testing and use of aircraft.

A picture of an airplane flying over some hills.
NASA tests airplanes as part of its aviation mission.
NASA

Sentences:
NASA does a lot of research in the field of aviation and flight safety.
The Wright brothers made aviation history with the first flight of their airplane.

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Axis

An imaginary straight line around which an object spins.

A graphic showing both the light and dark side of the earth with labels for the equator, tropics, and circles.
Seasons are caused by the tilt of Earth’s axis.
NASA

Sentences:
Earth spins on its axis once every 24 hours.
Earth’s axis goes from the North Pole through Earth’s center to the South Pole and is tilted.
 
Related Links:
What’s a Solstice?
What Causes the Seasons?

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