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Letter E

E is for …

Check out what E stands for …

Electricity
Electromagnetic Spectrum
Ellipse
Emergency Egress
Energy
Engineer
Equator
Escape Velocity
Exhaust
Experiment
Exploration
Extravehicular Mobility Unit

Electricity

Electric current, the movement of negative particles through a material, used as a source of power.

City lights on Earth glowing at night
Picture taken of Earth from space showing the glow from electric lights at night.
NASA

Sentences:
NASA uses solar power to make electricity on the space station.
During the thunderstorm, the electricity went out and we couldn’t watch TV.

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Electromagnetic Spectrum

All the wavelengths of visible and invisible light. Visible light is near the center of the spectrum.

A picture showing the electromagnetic spectrum from radio waves to gamma waves
This diagram shows the types of wavelengths going from longest to shortest.

Sentences:
Some NASA telescopes can see parts of the electromagnetic spectrum that we cannot see with our eyes.
Microwaves from the electromagnetic spectrum heat food in microwave ovens.

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Ellipse

A flattened circle or oval.

Diagram of an elliptical orbit, with the Moon's orbit around earth as an example.
The moon’s orbit around Earth is in the shape of an ellipse.
NASA

Sentences:
Earth’s orbit around the sun is in the shape of an ellipse.
A racetrack is shaped like an ellipse.

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Emergency Egress

A quick exit from a vehicle because of a dangerous situation requiring action right away.

A man practices an emergency escape through the docking port hatch at the top of a model of the Orion spacecraft
Men practice an emergency egress from the docking port hatch at the top of a model of the Orion capsule.
Lauren Harnett / NASA

Sentences:
Before launching on a spacecraft, astronauts practice emergency egress in case they have to escape quickly.
When schools have a fire drill, they are practicing emergency egress.

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Energy

The ability to do work.

Waterfall, wind turbine and solar panels
Water, wind and sunlight are three things that can be used to create energy.
NASA

Sentences:
Astronauts eat a healthy breakfast to give them energy to do their work.
A power plant can provide energy for an entire city.

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Engineer

A person who uses scientific facts to solve real problems.

NASA engineer Annie Caraccio standing in a laboratory
Annie Caraccio is an engineer who works with chemicals. She and her team want to know how astronauts can recycle trash.
NASA

Sentences:
My mom is an engineer who designs rockets for NASA.
If you like math or science, you may want to become an engineer.

Related Links:
Intro to Engineering Video

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Equator

An imaginary line drawn right around Earth’s middle, like a belt.

Map with equator labeled
On the first day of winter, which is usually around December 21, the sun’s rays shine directly on the equator.
NASA

Sentence:
The equator divides Earth into the Northern Hemisphere and the Southern Hemisphere.

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Escape Velocity

The speed needed for an object to break away from the gravitational pull of a planet or moon.

NASA’s New Horizon rocket sped away from Earth at an escape velocity of 36,000 miles per hour
NASA’s New Horizon spacecraft sped away from Earth at an escape velocity of 36,000 miles per hour.
NASA

Sentence:
Each planet has a different escape velocity.

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Exhaust

Hot gases released from a rocket motor or engine.

A launching rocket leaves a tall column of smoke beneath
An Atlas V (5) launches. It leaves a cloud of exhaust behind.
NASA

Sentences:
The rocket gave off big exhaust clouds during its launch.
Exhaust from cars and airplanes can cause pollution.

Related Links:
What Is a Rocket? (Grades K-4)
What Is a Rocket? (Grades 5-8)

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Experiment

A test or tests that are used to find out or prove something or to see whether an idea is correct.

Wearing a short-sleeved shirt and shorts, an astronaut puts his hand in a glovebox
Astronaut Bill McArthur sets up an experiment inside the Microgravity Science Glovebox on the International Space Station.
NASA

Sentences:
Astronauts perform many science experiments on the International Space Station.
My science class used lima bean seeds in a plant experiment.

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Exploration

The act of looking into or studying something unknown.

Curiosity rover on Mars
NASA sends rovers to Mars for exploration.
NASA

Sentences:
One day you might be part of an exploration team that travels to Mars.
My sister earned her exploration badge after she hiked through the woods.

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Extravehicular Mobility Unit

Another name for an airtight spacesuit worn by astronauts while working outside of the spacecraft in space.

An astronaut dressed in a large, bulky spacesuit waves to the camera while working in space
Astronaut Steven Swanson is shown in an EMU spacesuit while floating outside the International Space Station.
NASA

Sentences:
The white suit that astronauts wear when they are working in space is sometimes called their Extravehicular Mobility Unit, or EMU.
The EMU protects astronauts from the harmful environment of space.

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

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Explore More Letters

Go Back to NASA's Picture Dictionary

NASA's Picture Dictionary – F

NASA's Picture Dictionary – G

NASA's Picture Dictionary – H

NASA's Picture Dictionary – I