Theme: Exoplanets

 

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Text, Viewspace. The show will continue in 15 seconds. Coming up: Explore worlds beyond our solar system! 

 

The timer at top right counts down from 15 seconds. 

 

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The text appears on a background of stars which move slowly towards and past us. 

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The Hubble Space Telescope floats in space.

 

Text, When the Hubble Space Telescope was launched in 1990, the only planets we knew of were the ones in our own solar system.

 

Neptune, Uranus, Saturn, Jupiter, Mars, Earth, Venus, and Mercury in a row.

 

Text, Only a few years later, astronomers announced their discovery of the first planets outside our solar system.

 

Dark planets hang in space among blue gas streams.

 

Today, several thousand exoplanets have been identified.

 

Three planets orbit a red giant star.

 

Astronomers continue to uncover exoplanets just about every place they search, even where they didn't expect to find planets.

 

A red gas giant orbits a yellow star.

 

Ranging from giant, gaseous planets more massive than Jupiter to smaller rocky planets the size of our own Earth, these alien worlds seem to be plentiful.

 

A row of planets. Large colorful gas giants give way to watery planets and then rocky planets.

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A drawing above the word myth on the left of a mythical creature. Above the word reality on the right, an image of a star shining on a planet with stars against a dark background.

 

Text, Myth vs. Reality. Myth, The Hubble Space Telescope can take pictures of the surfaces of exoplanets. Reality, It is not possible for Hubble to photograph the surface or atmosphere of an exoplanet. Planets orbiting other stars are so far away, and so small and faint compared to their stars that at best they appear only as small, faint dots of light. However, Hubble can collect other data from exoplanets that can help us infer what the surface and atmosphere may be like.

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Text, CELESTIAL SIGNATURE.

 

Horizontal stripes of red, yellow, green, and blue have black splotches throughout.

 

Text, Cosmic secrets hide in starlight. Fortunately, astronomers possess a tool to uncover those secrets.

 

Called a spectrograph, this tool acts like a prism, separating light from a star into a rainbow of colors -- a spectrum.

 

Dark lines in the spectrum reveal elements and molecules in the star's atmosphere that absorb some of the starlight before it reaches Earth.

 

The exact positions of the lines tell us about the star's motion. The variation in brightness of the different colors reflects the star's temperature.

 

This is the spectrum of our star, the Sun.

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Galaxies in space above the Earth's curvature.

 

Text, at-a-GLANCE. USING LIGHT TO FIND EXOPLANETS.

 

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A sunrise above a planet's curvature against a backdrop of stars in space.

 

Text, Astronomers have discovered thousands of planets outside our solar system.

 

Most of these exoplanets, however, have never been seen.

 

Astronomers have found nearly all of them by examining the light of the planets' host stars as the light from those stars dims or shifts.

 

A planet passes in front of a star. A brightness scale below dips from 100% to 99% as the planet traverses in front of the star, then returns to 100% as the planet passes behind the star. This repeats.

 

Text, DIMMING, As they orbit, some planets pass in front of their stars from our point of view. When they do, they block a tiny bit of their star's light. A sensitive telescope can detect a planet by looking for minuscule, periodic dips in starlight.

 

By measuring the time that elapses between the dips, astronomers can figure out how long it takes the planet to orbit.

 

And from the amount of starlight blocked out, they can estimate the planet's size.

 

A planet orbits a star. A color spectrum bar is displayed above the star. As the planet orbits the star, the output colors on the spectrum bar shift back and forth from left to right. This repeats.

 

Text, SHIFTING. Although planets are puny compared to most stars, they do exert a small gravitational tug on the stars they orbit. Astronomers can detect this slight swaying motion by studying the star's spectrum. If the lines in a star's spectrum shift back and forth in a regular pattern, an orbiting planet could be pulling the star toward and away from us.

 

The period of the swaying lines reveals how quickly the planet orbits its star.

 

How much the lines sway depends on how massive the planet is.

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A star rises over a gas giant.

 

Text, ALIEN AIR. A star's light shines through the atmosphere of an orbiting exoplanet.

 

On its journey, some of the light is absorbed by atoms and molecules in the planet's atmosphere.

 

When that light reaches Earth, astronomers can inspect the starlight to find out what the planet's atmosphere is made of.

 

Someday, such filtered starlight could reveal that another planet in our galaxy is habitable -- or inhabited.

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A nebula in space, a cluster of dense clouds in shades of red, purple, and yellow, speckled with bright stars. Text, In the 1990's the Hubble Space Telescope peered deep into the stellar factory we call the Orion Nebula.

 

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Small dark disc shaped objects appear in circles. Text, There it found disks of dust and gas swirling around many young stars. These disks are the birthplace of planets.

 

Hubble cannot gaze into the disks to see planets forming within though. An animation of a Disk, a bright center surrounded by a ring of dark clouds.

 

Text, Thick dust blocks the view.

 

However, with its ddust penetrating infrared vision, Nasa's James Webb Space Telescope can look deeper inside these disks. Animation of the disk's reddish clouds spinning around the central bright point.

 

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Text, Webb can study the chemical compositions of the disks.

 

It will compare young and old disks to see how they change with time.

 

Text, Webb will find out how the composition of those disks compares with molecules in our own solar system.

 

A line of pale clouds creating a horizon against a backdrop of black space filled with stars, a bright glowing white light on the edge. A small dark sphere grows larger as it approaches.

 

Text, It might even be able to see planets forming within the disks.

 

In infrared light, planets are easier to find since stars appear dimmer and planets appear brighter. An illustration of a grayish blue planet next to a massive bright yellow star. Text, Visible view, illustration. The planet turns bright orange and the star becomes dimmer blue. Text, Infrared view, illustration.

 

A Hubble image of glowing orange specks in a deep blue background. Text, Only a few planets have been spotted in infrared light. These were uncovered in archived Hubble observations after being discovered by ground-based telescopes.

 

Only after their host star's light had been removed could the planets be seen. A bright splash over the specks of planets appears, leaving them less visible. Text, Hubble Infrared Image with Starlight. The splash disappears, revealing the planets again. Text, Hubble Infrared Image without Starlight.

 

Text, Using this same technique, Webb can discover and study more planets orbiting other stars. An illustration of the James Webb telescope, its hexagonal gold plates mounted upright on a long metal craft with long arms extending from the plate's edges forming a point in front of it.

 

The hazy surface of a reddish planet. Text, In 2000, Hubble became the first telescope to detect the atmosphere of an exoplanet.

 

When the Jupiter-like planet traveled in front of its star from our point of view, some of the starlight filtered through the planet's atmosphere. A small round planet passes in front of a blazing star.

 

Text, When that filtered light reached Hubble, it was imprinted with the chemical composition of the planet's atmosphere. An illustration of light passing from the planet through a prism and into a band of rainbow visible light with two stripes missing in the yellow area. Below the band of colors, a graph showing deep grooves where the stripes in the light band are.

 

Animated water, carbon dioxide, and methane molecules spin over a jagged line graph of the spectrum of the planet's atmosphere. Text, In the atmospheres of this and other Jupiter-like planets, Hubble has found such things as water vapor, carbon dioxide, oxygen, and methane. These are some of the atmospheric ingredients we seek when searching for life on other worlds.

 

But we don't expect life -- at least the kind we're familiar with -- to exist on those gaseous surfaceless planets.

 

Webb can study the atmospheres of smaller planets -- perhaps even rocky planets with land or oceans where life could flourish. An animated small planet floats in the blackness of space against a blanket of stars. It rotates around a red star.

 

Text, One day, Webb could become the first telescope to identify hints of life on a planet much like our own.

 

Webb can study the atmospheres of smaller rocky planets that are similar to Earth's size.

 

Webb could detect molecules like water and methane on these distant worlds, gathering evidence to help us identify those with conditions that may be suitable for life.

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Top left, a black and white picture of a minotaur. Top right, a color picture of a planet.

 

Text, MYTH versus REALITY

 

Myth side

 

Text, Planets do not give off any light of their own.

 

Reality side

 

Text, It is true that planets emit very little visible light. Most of the visible light from planets is reflected starlight. But planets do emit a significant amount of their own infrared light. In fact, the infrared light of a planet is often easier to detect than the reflected visible light.