Practice English Speaking&Listening with: NASA | JWST Feature - Planetary Evolution

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The places where

The places where

stars and planets are born are among the galaxy's most beautiful

locales. These cosmic landscapes change as new generations

of stars light up and disperse their birth cloud. But the youngest

stars seen here are already perhaps a million years old.

Hardly toddlers.Stars and planets

inside vast, cold clouds of gas and

dust, such as these pillars imaged by the Hubble Space Telescope.

The dust is so thick we can't see the infant stars inside.

At least, not with visible light.

With infrared light, Hubble can see through all but the thickest dust.

Yet it's in those dense knots that the youngest

stars are forming. To peer inside them,

astronomers need the James Webb Space Telescope. With a mirror

larger than Hubble's and performance optimized for the infrared,

Webb will give astronomers their closest look yet at stellar birth.

We're flying through a computer model that represents astronomers' best

ideas about the star formation process.

Redder colors indicate thicker dust. The temperature? Less than 400

degrees below zero Fahrenheit - or less than

240 degrees below zero celsius.

That pinwheel ahead is a protostar, perhaps

10,000 years old. Protostars arise when a dense

knot of dust less than a light-year across collapses,

but the details of the process are not well known.

Elsewhere in

the cloud, another protostar is preparing to build planets.

As the cloud that created the protostar collapsed, it flattened into a

disk. The disk we see here is 600 times the size of

of Earth's orbit around the sun. If placed in our solar

system, it would extend far beyond the planets.

In this computer model, the disk continues to accumulate gas and dust

from its surroundings for thousands of years. Eventually,

the disk fragments, producing dense, bright structures.

These may become sites where giant planets form.

Later, during another phase of construction, smaller,

Earth-size planets may take shape.

At least, that's what scientists think happens.

It will take the Webb telescope's keen infrared eye to see what's really

going on in the cold heart of stellar nurseries.

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