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This is the Hubblecast.

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News and images from the
NASA / ESA Hubble Space Telescope.

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Travelling through time and space
with our host, Dr. J

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EPISODE 19: Bigger is better.
a.k.a. Dr. Joe Liske.

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Welcome to the second special
episode of the Hubblecast,

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celebrating the International
Year of Astronomy 2009.

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In the first episode we learned
about the invention of the telescope

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and how it facilitated man's
first steps out into the Universe.

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Today we will see how astronomers
use bigger and bigger telescopes

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to see further than ever before.

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At night your eyes adapt to the dark.

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Your pupils widen to let
more light into your eyes.

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As a result, you can see dimmer
objects and fainter stars.

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Now imagine you had
pupils one metre across.

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You'd look pretty strange but you'd
also have supernatural eyesight.

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And that's what telescopes do for you.

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A telescope is like a funnel.

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It's main lens is or mirror collects the
starlight and brings it all together into your eye.

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The bigger the lens or the mirror of the
telescope, the fainter the objects you can see.

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So, size really is everything.

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But how big can you make a telescope?

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Well actually not too
big if it's a refractor.

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The starlight has to pass
through the main lens.

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And so you can only support it around its edge.

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If you make the lens too
big it becomes too heavy

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and it starts deforming
under its own weight.

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That means that the
image will be distorted.

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The largest refractor in
history was completed in 1897,

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at Yerkes Observatory outside Chicago.

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It's main lens was just
over one metre across.

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But it's tube was an
incredible 18 metres long.

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With the completion of
the Yerkes telescope,

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the builders of refractor telescopes
had pretty much reached their limit.

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You want bigger
telescopes? Think mirrors.

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In a reflecting telescope the
starlight bounces off a mirror

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instead of passing through a lens.

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That means that you can make the
mirror a lot thinner than a lens

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and you can support it from the back.

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The result is that you can build
a lot larger mirrors than lenses.

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Big mirrors came to southern
California a century ago.

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Back then, Mount Wilson was a remote peak
in the wilderness of San Gabriel mountains.

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The sky was clear and
the nights were dark.

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Here, George Ellery Hale first
built a 1.5 metre telescope.

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Smaller than Lord Rosse’s retired
Leviathan, it was of much better quality.

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And at a much better site, too.

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Hale talk local businessman John Hooker
into financing a 2.5 metre instrument.

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Tonnes of glass and riveted
steel were hauled up Mount Wilson.

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The Hooker telescope
was completed in 1917.

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It would remain the largest
telescope in the world for 30 years.

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A big piece of cosmic artillery,
ready to attack the Universe.

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And attack it did.

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Along with the incredible
size of the new telescope

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came transformations in the
way the image was viewed.

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Astronomers no longer peered
through the eyepiece of the new giant.

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But instead collected the light on
photographic plates for hours on end.

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Never before had anyone
peered so far into the cosmos.

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Spiral nebulae turned out to be
brimming with individual stars.

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Could they be sprawling stellar
systems like our own Milky Way?

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In the Andromeda Nebula, Edwing Hubble
discovered a particular type of star

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that changes its brightness
with clock-like precision.

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From his observations Hubble was able
to deduce the distance to Andromeda:

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almost a million light-years.

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Spiral nebulae, like
Andromeda, were clearly

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individual galaxies in their own right.

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But that wasn't the only incredible thing.

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Most of these galaxies were found
to be moving away from the Milky Way.

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At Mount Wilson, Hubble discovered that the
nearby galaxies were receding at small velocities

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whereas the distant galaxies were
moving away at a much faster pace.

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The conclusion?
The Universe was expanding.

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The Hooker telescope had given scientist

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the most profound astronomical
discovery of the 20th century.

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Thanks to the telescope we have
traced the history of the Universe.

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A little less than 14 billion
years ago, the Universe was born

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in a huge explosion of time and space,
matter and energy, called the Big Bang.

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Tiny quantum ripples grew into
dense patches in the primordial brew.

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From these, galaxies condensed.

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A stunning variety of sizes and shapes.

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Nuclear fusion in the cores
of stars produces new atoms.

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Carbon, oxygen, iron, gold.

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Supernovae explosions blew these
heavy element back into space.

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Raw material for the
formation of new stars.

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And planets!

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Someday, somewhere, somehow,

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simple organic molecules
evolved into living organisms.

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Life is one miracle in
an ever-evolving Universe.

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We are stardust.

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It's a grand vision
and a sweeping story.

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Brought to us through
telescopic observations.

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Imagine: without the telescope

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we would know about just six planets,
one moon and a few thousand stars.

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Astronomy would still be in its infancy.

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Like buried treasures, the
outposts of the Universe

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have beckoned to the adventurous
from immemorial times.

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Princes and potentates, political or
industrial, equally with men of science,

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have felt the lure of the
uncharted seas of space,

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and through their provision
of instrumental means

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the sphere of exploration
has rapidly widened.

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Butch Ellery Hale had one final dream:

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to build a telescope twice as
large as the previous record holder.

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Meet the grand old lady
of 20th century astronomy.

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The five metre Hale
telescope at Palomar Mountain.

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Over five hundred
tonnes of moving weight,

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yet so precisely balanced that it
moves as gracefully as a ballerina.

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Its 40 tonne mirror reveals stars 40
million times fainter

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than the eye can see.

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Completed in 1948, the Hale
telescope gave us unsurpassed views

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of planets, star clusters,
nebulae and galaxies.

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Giant Jupiter, with its many moons.

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The stunning Flame Nebula.

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Faint wisps of gas in the Orion Nebula.

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But could we go bigger still?

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Well, soviet astronomers
tried in the late 1970s.

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High up in the Caucasus mountains they
built the Bolshoi Teleskop Azimutalnyi,

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sporting a primary mirror
six metres in diameter.

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But it never really lived
up to its expectations.

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It was simply too big, too
expensive and too difficult.

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So, did telescope builders
did to give up at that point?

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Did they have to bury their
dreams of ever bigger instruments?

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Had the history of the telescope
come to a premature end?

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Well, of course not.

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Today we have 10 metres
telescopes in operation.

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And even bigger ones
are on the drawing board.

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What was the solution?
New technologies.

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Thank you for joining me in this
second episode of the special series.

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Next time, we will see how advancing
technology revolutionised astronomy.

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This is Dr. J
signing off for the Hubblecast.

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Once again, nature has surprised us
beyond our wildest imagination...

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Hubblecast is produced
by ESA / Hubble

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at the European
Southern Observatory in Germany.

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The Hubble mission is a project
of international cooperation

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between NASA and
the European Space Agency.