The space between stars holds an array of vibrant clouds.
Clouds that command our attention.
Clouds that create spectacular displays.
Clouds that seem familiar, tenuous, and fragile.
Clouds that hold clues to star birth, and death.
NASA’s Hubble Space Telescope has imaged hundreds of them in extraordinary detail.
These vast swirls of gas and dust get their name from the Latin word,
nebula, meaning “cloud” or “mist."
"Nebulae" is the plural of "Nebula," and they come
in a wide range of shapes, sizes, and forms.
Emission nebulae are some of the most spectacular.
These opaque, gleaming clouds of gas and dust radiate, or emit, their own light.
Ultraviolet light from nearby stars energizes atoms in the cloud.
When the excited atoms lose that energy,
they release the light that gives emission nebulae their glow.
The Orion Nebula is one of the most famous emission nebulae.
Its core, called the Trapezium, holds four enormous young stars
whose ultraviolet light powers the region’s intense glow.
The Carina Nebula is another vast emission
nebula and star-forming region in our galaxy.
Within the nebula is a pillar three light years tall, dubbed Mystic Mountain.
It cloaks massive young stars, some with jets emerging from the cloud.
Hubble’s infrared view cuts through the shroud of gas and dust,
revealing these radiant jewels.
Reflection nebulae shine by the reflected or scattered light of nearby stars.
They often have a bluish color because the dust grains in the cloud scatter blue light
more efficiently than red light.
Not all nebulae shine brightly.
Dark or absorption nebulae are inky-black clouds of gas and dust that block the light
coming from objects behind them.
Because they are dark, absorption nebulae are hard to find.
We only see them as silhouettes against a much brighter region of space.
Most large nebulae are a combination of emission, reflection, and absorption nebulae.
Their dark dust lanes may give birth to new stars
that provide the light needed to illuminate the cloud.
Planetary nebulae are a type of emission nebula powered by a small to medium-sized dying star.
As these stars run out of fuel, they periodically blow off their outer layers.
The expelled gas expands outward, away from the star,
forming a bubble, or shell, around the star.
Sometimes, the envelope of debris holds clumps of dense gas
that shine like the gems of a necklace.
The term “planetary nebula” is misleading. It comes from late eighteenth-century astronomers
who thought their rounded shape looked similar to planets in telescopes of that time.
They named them “planetary nebulae" as a result.
Supernova remnants are the diffuse clouds of expanding debris
released by a massive star’s death explosion.
The Cygnus Loop is a vast, expanding 110-light year-wide supernova remnant.
It is so large that Hubble can only image small sections of it at a time.
Some supernova remnants emit their light from a shell of shocked material.
Others, like the Crab Nebula, emit most of their light from within the expanding shell.
And still other supernova remnants shine as a combination of the two.
Nebulae are some of the most resplendent objects in the universe,
and thanks to the Hubble Space Telescope,
we can study them in all of their magnificent forms.
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