paraphrase the 1995 movie Apollo 13, that was
only what Hubble was designed to do. Now we
know more about what it can do.Take exoplanets as an example. he irst widely
accepted exoplanet announcement — a pair of
planets circling a pulsar — took place on January
9, 1992. Hubble wasn’t designed to look at exoplan-
ets because frankly, nobody knew they existed
before the telescope launched. But a few instru-
ment upgrades did the trick. In September 2019,
Hubble oicials announced the telescope found
water vapour at a distant exoplanet, just one of
its many remarkable discoveries about distant
planets outside our solar system.Closer to home
Hubble is also a boon for planets closer to home.
Space missions are expensive. It’s hard to send
spacecraft to see the outer solar system planets
of Jupiter, Saturn, Uranus, and Neptune. Hubble
captured images of amazing sights such as water
spurting out of the Jovian moon Europa, and the
dusty, chaotic aftermath of asteroids crashing into
each other. It also looked at the outer planets from
time to time, coming up with interesting results
again and again.Heidi Hammel, now a senior research scientist at
the Space Science Institute in Boulder, Colorado,
remembers making a request for Hubble time to
observe Neptune in 1994, about ive years after the
Voyager 2 spacecraft made a speedy lyby near the
blue planet. Among Voyager 2’s most spectacular
inds was a huge storm, instantly nicknamed the
Great Dark Spot.“I want to follow up on this Great Dark Spot,
right?” Hammel said. “And when we got the data,
it wasn’t there. It was gone. It had disappeared
sometime in the intervening ive years. It went
from being the most prominent feature on the
planet, to being gone.”Why did it disappear? We don’t have a deinitive
answer. hat was just one reason that astronomers
kept pushing the keepers of Hubble telescope time
to give time, every year, to examine outer planets.
hey argued change happens too quickly for spo-
radic observations every few years, which would
happen in the normal course of a competitive
request for telescope time. So in 2014,
Hubble granted time to a program called theOuter Planets Atmosphere Legacy to add to
the telescope’s long record of observing all of
these planets. OPAL guarantees a few weeks of
telescope time per Earth-year to look at each
planet for signs of change.Hubble’s contributions to OPAL in ive years are
already numerous. Astronomers can keep an eye
on the Great Red Spot of Jupiter, which has been
shrinking for decades. he reasons are still poorly
understood, but they lurk somewhere in the deep
clouds of the planet. At Uranus, astronomers are
watching storms pop up as diferent regions of
the planet are exposed to sunlight. he planet is
tilted on its side as it whirls around the sun every
84 years, so sometimes its poles are exposed and
sometimes its side is. Insights are coming in about
Saturn’s and Neptune’s atmospheres, too.Hammel argued the space telescope is far better
positioned to watch these planets every year than
even the most powerful ground observatories.
For one thing, Hubble is in space — far above the
atmosphere that obscures observations, especially
in ultraviolet wavelengths. It is also optimized
to give high detail in blue wavelengths, the same
wavelengths in which Uranus and Neptune clouds
shine most brightly.Deep field objects
Farther aield, Hubble is famous for numerous
images of huge, faraway objects. Many “deep ield”
observations showed galaxies popping up in the
early universe. hese are twisted, stunted objects
— often merging with each other — that look
nothing like the serene spiral curves of the Milky
Way in which we live. Wiseman is quick to point
out, however, that the Milky Way’s calm appear-
ance is an illusion: Hubble also found out the
Andromeda Galaxy (M31) is on an inevitable
collision course with our own neighbourhood.
Change is ever a constant.Hubble’s observations from the dawn of the
universe are valuable, because they show us
change over a cosmic timescale of 13.8 billion
years. In fact, Hubble will team up with an
upcoming NASA observatory — the James Webb
Space Telescope, which should launch in 2021 —
to better explore the beginning of our universe.
Webb is even better optimized to see this “early
dawn” than Hubble, so astronomers are eager to
see the results. →SKYNEWS • MAR/APR 2020