Hubbles Canvas_5of6_Grand Design and Stretching the Canvas
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00:00In the quest to explore the universe, our greatest ally is the Hubble Space Telescope.
00:09No scientific instrument in history has revealed so much or taken us so far.
00:19Perched above the distorting veil of Earth's atmosphere, Hubble sees what we cannot.
00:25Using vivid color to represent scientific data, Hubble paints pictures of unprecedented clarity.
00:31Pictures that bridge the domains of art and science,
00:35and form a direct link between the most powerful forces in nature and the human spirit.
00:55A great work of art is more than the sum of its parts.
01:16Although the artist works at the level of small detail, brushstroke by brushstroke,
01:21there is a larger idea at work, a design that expresses the artist's true intention.
01:33When the Hubble Space Telescope looks toward the heavens, it finds design on a grand scale,
01:41especially when it zooms in on the magnificent spiral galaxies that populate the universe around us.
01:52But rather than expressing the conscious will of the artist,
01:57this kind of design reveals the interplay of nature's fundamental laws.
02:14Our solar system is part of a galaxy called the Milky Way.
02:19The Milky Way, too, is a spiral galaxy composed of hundreds of billions of individual stars,
02:25all moving separately around a common center of gravity.
02:32Yet through all of these separate motions, nature has achieved a single overarching design.
02:43Galaxies were not part of the universe of our ancestors.
02:48It was not until the 1840s that telescopes were powerful enough
02:53to reveal the tiny blobs and swirls scattered among the stars.
02:59At that time, even the word galaxy didn't exist.
03:04Astronomers believed everything they saw was part of the Milky Way,
03:09which appears to us as a great band of stars running across the night sky.
03:26So what were these strange spiral shapes that kept showing up in those first deepest glimpses of space?
03:35Many astronomers thought they were watching new solar systems coalescing among the stars.
03:43In the 1920s, American astronomer Edwin Hubble put an end to this idea forever.
03:51It was Hubble who proved that these beautiful spirals are not part of the Milky Way at all.
04:00Rather, they are entirely separate star systems,
04:05each just as vast as the Milky Way but seen from a great distance.
04:12Hubble also recognized that many of the largest and brightest galaxies are not spirals at all.
04:20Instead, they are enormous and rather football-shaped concentrations of stars,
04:26which Hubble called elliptical galaxies.
04:34It has taken another generation of astronomers to understand why some galaxies are elliptical
04:40while others display a striking spiral design.
04:46One clue has to do with the fact that spirals are much flatter than ellipticals.
04:56While elliptical galaxies are football-shaped, spirals are thin disks.
05:03This becomes obvious when a star is seen from a distance.
05:09Spirals are thin disks.
05:13This becomes obvious when a spiral galaxy is viewed edge-on rather than face-on.
05:32By analyzing the light from spiral galaxies,
05:36astronomers have found that they are disk-shaped because they are spinning rapidly.
05:52It's the force of their own rotation that causes them to flatten out,
05:57like pizza dough spinning in the air.
06:01This fact also complicates our understanding of the spiral arms.
06:10Since the arms are not rigid objects but made of billions of individual stars,
06:16it's hard to see how those stars can possibly turn together around the galaxy's center
06:22to maintain their spiral arrangement.
06:27Gravity dictates that just the opposite should occur.
06:37In our solar system, the planets that are nearest to the center orbit most quickly.
06:49In a spiral galaxy, the stars that are nearest to the galaxy's center
06:55should also be orbiting with the greatest speed.
07:00But if this is so, then a spiral pattern like this would wrap around itself
07:06after just a few turns and become stretched out beyond recognition.
07:12Some other explanation is needed to account for why spiral arms persist.
07:26Hubble images like this one appear to confirm the theory
07:32that in some galaxies, spiral arms move through the stars like giant waves.
07:39For example, the stars in this galaxy are all orbiting the galaxy's center,
07:45each at its own pace.
07:48But as they orbit, they are also passing in and out of the center of the galaxy.
07:54This means that the stars that are closest to the center
07:58are also orbiting the center of the galaxy.
08:03But as they orbit, they are also passing in and out of the galaxy's spiral arms.
08:11Meanwhile, the arms are moving too.
08:15Not as solid structures, but as shifting concentrations of matter
08:20that sweep around the galaxy like waves rolling across the ocean.
08:33With its unprecedented ability to resolve fine detail,
08:37the Hubble Space Telescope has become the premier instrument
08:41for showing us how spiral arms are formed and maintained.
08:46Astronomers are still trying to understand
08:49why spirals can look so different from one another.
08:55The Hubble has examined many of the nearest spiral galaxies,
09:00and they display as much variety as faces hanging in a portrait gallery.
09:25In some cases, the arms of a spiral galaxy can appear numerous and feathery,
09:31like the vortex of a cosmic hurricane wheeling through intergalactic space.
09:44In other cases, the spiral pattern is more distinct,
09:49with just a few large arms winding outward from the galaxy's core to its outskirts,
09:55a span so great light would take tens of thousands of years to cross it.
10:01Appropriately, this kind of galaxy is called a grand design spiral,
10:07and it makes a stunning subject for Hubble's perceptive gaze.
10:14Still other spiral galaxies have long, straight bars running across their centers,
10:20with spiral arms sprouting dramatically from the center of the galaxy,
10:26as if they were floating in the air.
10:30In the case of a spiral galaxy,
10:33the arms of a spiral galaxy can be as large as the size of a football.
10:40From an artistic perspective,
10:44all these different kinds of spirals can be thought of as variations on a theme.
10:57It's clear that gravity and rotation dictate the general plan,
11:03It's clear that gravity and rotation dictate the general plan,
11:09but how that plan unfolds depends on the specific conditions particular to each galaxy.
11:19One important factor may be whether the galaxy is isolated in space or has another galaxy nearby.
11:33Without question, the most striking example of why this matters is the Whirlpool galaxy.
11:41This is an awesome grand design spiral,
11:45featuring two bright arms beautifully coiled around each other.
11:50But it's not just the graceful arms of the Whirlpool
11:54that give this galaxy its unmistakable appearance.
11:59Right beside it is a smaller galaxy that appears to be a companion.
12:05In this, the best image ever taken of the Whirlpool,
12:10Hubble shows that the impression of a bridge between the galaxies is an illusion.
12:18The smaller galaxy is farther away, well behind the overlapping spiral arm.
12:27Nevertheless, the smaller companion is having a profound effect on the Whirlpool.
12:35The pull of its gravity on the dust and gas of the larger galaxy
12:40is the likely stimulus that led to the formation of these remarkable spiral arms.
12:48Through Hubble's powerful optics,
12:54the arms can be seen as the crests of great waves of star formation.
13:01In sequence, we see long lines of dark dust,
13:05the raw material for a new generation of stars.
13:10They are followed by bright pink clouds,
13:14where newborn stars are already making the surrounding gas glow.
13:20Finally, we see clusters of bright blue stars
13:24that were produced earlier as the wave of star formation swept through.
13:31Somewhere among all of these stars and dust and gas,
13:35it's certain that solar systems are forming too,
13:39perhaps with planets capable of sustaining life.
13:43In the grand design of the Whirlpool galaxy,
13:46we may, in fact, be witnessing the birth of a future galactic civilization.
13:55As inhabitants of the Milky Way, a spiral galaxy not so different from this one,
14:01we can easily infer that our own destiny was launched in the same way,
14:05on the crest of a spiral arm billions of years ago when our solar system formed.
14:11This is ultimately what is most profound about the elegant designs of spiral galaxies.
14:16They're not simply beautiful to look at,
14:19they are the shape of renewal and life in the universe.
14:28Formed by gravity and rotation,
14:31spiral galaxies require no higher intelligence to exist,
14:35but in their existence, they make possible the emergence of creatures such as ourselves
14:41that can build telescopes and gaze at the galaxies in wonder.
15:05What is the Universe made of?
15:27What is the Universe made of?
15:31To the eye and to telescopes sensitive to the visible wavelengths of light,
15:36the answer is clear.
15:38The Universe is made of stars,
15:41and the enormous congregations of stars we call galaxies.
15:46Look in any direction and you will see them,
15:50distant islands of light floating in an empty void.
15:55But this picture is far from complete.
16:00Today, astronomers realize that space itself is like a canvas
16:05upon which the stars and galaxies are set.
16:09And there is much more to this cosmic canvas than meets the eye.
16:15Now, thanks to the Hubble Space Telescope in combination with other observatories,
16:20astronomers have confirmed that the canvas of space is being stretched in all directions.
16:26Even where it appears most empty,
16:28our Universe is in the midst of a tug of war
16:31between the unseen influences of dark matter and dark energy.
16:35Using Hubble, these influences can be measured, but not directly.
16:42The word dark matter conjures up the vision of black clouds adrift among the stars.
16:50But dramatic images like this are simply showing the presence of ordinary dust
16:55which absorbs starlight.
16:59Real dark matter neither absorbs nor emits light.
17:03It's not really dark at all, but utterly transparent.
17:16Its existence was not suspected until astronomers studying distant clusters of galaxies
17:21realized there was not enough matter in these galaxies
17:25for their mutual gravity to hold them together as a group.
17:35Somehow, there had to be more matter than was visible in the galaxies themselves.
17:45Then, studies of spiral galaxies like this one
17:49revealed there was something peculiar about the way these galaxies rotate.
17:55The stars at the edge of the galaxy should orbit much more slowly than stars near the center.
18:01But they do not.
18:03At least not as slowly as they should.
18:08The way to explain these unexpected motions, astronomers realized,
18:12was to imagine that each galaxy is embedded within a much larger
18:16but entirely invisible concentration of dark matter.
18:23In fact, astronomers now estimate that for every galaxy we can see,
18:28there is five times as much dark matter that we cannot.
18:33With the help of Hubble's keen eye,
18:36the fingerprint of dark matter can be found everywhere.
18:43Here, a dense cluster of galaxies exerts enough gravitational pull
18:48to bend light and distort the appearance of galaxies that lie further in the background.
18:54This effect is known as the Higgs boson.
18:58This effect, known as a gravitational lens,
19:02can be used to precisely measure the quantity of dark matter that surrounds the cluster.
19:12On a larger scale, astronomers have now used Hubble to gaze
19:16into relatively empty patches of space
19:19where background galaxies are distorted only slightly.
19:23Yet even such slight distortions can provide enough information
19:27to create a map in three dimensions
19:30that shows the distribution of dark matter that lies between us
19:34and these distant galaxies.
19:42This unusual image shows what may be the strongest evidence yet for dark matter.
19:48It depicts Hubble's view of two clusters of galaxies in the act of colliding.
19:55Both clusters contain hydrogen gas,
19:58which is energized enough to give off X-rays.
20:01The location of the gas is color-coded pink.
20:07Meanwhile, the blue color shows where the dark matter in this collision is located,
20:12based on the distortion of the gas.
20:18This is a depiction of background galaxies.
20:29The simple fact that the blue has separated from the pink
20:33means that two great clouds of dark matter have passed through each other
20:38as easily as ghosts,
20:42while the gas clouds have collided, compressed, and heated up.
20:49Clearly, dark matter must be different from ordinary matter
20:54with very different properties.
20:58Hubble's detective work has finally glimpsed the trace
21:01of something human eyes were never designed to see.
21:10The combined gravity of matter plus all the dark matter in the universe
21:16should noticeably affect how the universe evolves.
21:24The universe has been expanding ever since the Big Bang,
21:28but over time, gravity should be slowing down the expansion.
21:34After its launch, one of Hubble's first big tasks
21:38was measuring the expansion of the entire universe.
21:42This may seem like an impossible feat,
21:44but Hubble did it by carefully searching nearby galaxies like this one
21:49for a special type of variable star.
21:54Stars of this type pulsate with a regular cycle, like a heartbeat.
22:00The rate of the pulse is related to a star's energy output
22:04and therefore to its overall brightness.
22:08Simply by timing a star's pulsations,
22:11Hubble can tell us how far away the star is.
22:16This is exciting news!
22:18Hubble is the only telescope that can resolve pulsating stars
22:22in other galaxies well beyond our home galaxy, the Milky Way.
22:29And though the stars only take up a few pixels of each image,
22:33Hubble's views are good enough to record and time their pulsations.
22:42The Big Bang
22:52Once the measurements were made,
22:54Hubble could finally tell us how far away these galaxies are.
23:01And when combined with other observations,
23:03they provided the most accurate estimates yet
23:06for the expansion rate and the age of our universe.
23:12The Results
23:14The results were unexpected.
23:16According to Hubble, the universe was less than 12 billion years old.
23:21Yet independent measurements of the oldest stars in our galaxy,
23:25also made by Hubble, showed they were older.
23:29And that posed a problem.
23:31How could the universe possibly be younger than the stars it contains?
23:37To answer the question, astronomers again turned to Hubble,
23:42this time using the space telescope
23:44to look for a specific type of supernova, or exploding star.
23:51Like a pulsating star,
23:53a supernova can be used to measure the distance to a galaxy.
23:58But it's bright enough to be seen from much farther away.
24:07Because the light from these galaxies takes longer to reach us,
24:11Hubble's measurements reveal
24:13how the expansion of the universe has changed over time.
24:28And after looking at many more of these faraway explosions,
24:32astronomers have come up with an astounding result.
24:39Because of the combined gravity of all the matter and dark matter it contains,
24:44the expansion of the universe should be slowing down.
24:48Instead, it's actually speeding up.
24:52It was this revolutionary finding
24:55that allowed astronomers to realize something else is at work in the cosmos,
24:59a dark energy that appears to be woven into the very fabric of space itself.
25:07Astronomers are still trying to understand exactly what dark energy is,
25:11and what will happen in the far future
25:14as the universe continues to expand faster and faster.
25:20For now, we can say that when Hubble stares off into space,
25:24it's showing us the battleground of a titanic struggle
25:28between invisible forms of matter and energy.
25:38The art of Hubble plays out on a restless canvas,
25:42a canvas that dictates not only everything we see,
25:46but our own destiny in the universe.
25:54Hubblecast is produced by ESA, the European Southern Observatory.
25:58The Hubble mission is a project of international cooperation
26:02between NASA and the European Space Agency.
26:06The Hubble mission is a project of international cooperation
26:10between NASA and the European Space Agency.
26:24The Hubble mission is a project of international cooperation
26:28between NASA and the European Space Agency.