NASA’s Hubble Space Telescope launched on April 24, 1990, and it’s been hard at work
ever since, studying the cosmos like no other observatory in human history.
Several times in its journey, astronomers have called upon Hubble to study a single
spot in the sky for weeks at a time, staring as far as it can, almost to the edge of the
observable Universe.
These are the deep fields, including the most recent Hubble eXtreme Deep Field.
Now all of these data have been mashed together into a single image, spanning more than 250
days of observations.
It’s called the Hubble Legacy Field.
It’s full of galaxies.
After the launch of Hubble NASA and ESA realized they had a big problem with the telescope’s
optics, one that could only be repaired by astronauts physically visiting and fixing
the telescope.
Astronauts arrived in December 1993 with new instruments and the equipment that it would
take to fix the flaw.
Once the mission was complete, astronomers took some test images of an empty region of
the sky to calibrate the telescope’s new optics.
What looked like empty space to other telescopes was revealed to be filled with galaxies in
the eyes of Hubble.
In 1996, Hubble performed its first Deep Field Survey, staring at a region of the sky near
the constellation Ursa Major for more than 100 hours, over 10 consecutive days, gathering
342 separate exposures.
They chose this region because it’s high above the Milky Way, and is as empty as possible
of foreground stars.
The field was tiny; imagine the size of a dime located 23 meters or 75 feet away.
In this single image, Hubble turned up almost 3,000 galaxies, most of which had never been
seen before.
Galaxies which were 4 billion times fainter than can be seen by the human eye.
And in this image, astronomers saw galaxies 10 billion years old, at a time when the Universe
was less than a third of its current age.
It was like using a time machine to go back to the early Universe to see what it looked
like near the beginning of time itself.
Over the next few years, Hubble received several upgrades.
Astronauts flew back to the aging telescope to fix its failing gyros and install additional
instruments.
On March 1, 2002, astronauts arrived to install its most sensitive instrument yet: the Advanced
Camera for Surveys.
This was a modern astronomical CCD camera that was 10 times more sensitive than the
previous camera, allowing Hubble to look even farther into space and further back in time.
It was time to do another deep field.
In 2004, NASA and ESA released the Hubble Ultra Deep Field, another marathon observing
session that took advantage of the newly installed Advanced Camera for Surveys.
This time Hubble stared into a tiny region in the constellation Fornax for one million
seconds or 11 and half days.
In this one image, a region that ground-based telescopes find mostly empty, Hubble saw 10,000
galaxies.
Young galaxies, old galaxies, and galaxies smashing into each other.
Some were seen at a time 13 billion light-years ago, less than a billion years after the Big
Bang itself.
Hubble then viewed these same regions in infrared using its Wide Field Camera 3, finding objects
that were even more distant, just 450 million years after the Big Bang.
In 2012, astronomers released the eXtreme Hubble Deep Field.
This wasn’t a new set of observations, but a combination of all the data Hubble had captured
in the Fornax region.
The overlapping observations took up a smaller part of the sky, containing only 5,500 galaxies,
but with more more sensitivity.
The faintest are one ten-billionth the brightness of what the human eye can see.
And finally, this week, NASA and ESA announced their latest work from the telescope: the
Hubble Legacy Field.
250,000 galaxies in one picture.
And we’ll get to that in a second, but first I’d like to thank Patrons some more special
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Okay, I’ll admit, this video was mostly just me being nostalgic about the Hubble Deep
Field pictures.
But I promised news.
Let’s get into it.
Last week, we got to see the newest image from the Deep Field series.
It’s called the Hubble Legacy Field, and it’s made up of 16 years of Hubble observations.
This image is a mosaic, made up of 7,500 individual exposures, and contains 265,000 galaxies stretching
back to 13.3 billion years ago, just 500 million years after the Big Bang.
The raw data in the image covers wavelengths from infrared through visible to ultraviolet,
revealing every stage of galaxy formation.
From the earliest proto galaxies to the more recent mature galaxies.
Many are the result of collisions between galaxies and even galaxy clusters in the early
Universe, stirring up regions of furious star formation.
This photo is much wider than previous surveys, covering a region of the sky about as big
as the full Moon; a region that encompasses the original eXtreme Deep Field and much more.
All in all, Hubble has spent 250 days observing this one region of the sky, more time than
anywhere else it’s looked.
265,000 galaxies in one picture.
Mind blown.
Of course, their work isn’t done.
A second set of images are the works, which will be made up of more than 5,200 exposures.
And the team is planning to combine these with surveys taken by NASA’s other Great
Observatories, Spitzer and Chandra, to add longer wavelength infrared and high energy
X-rays to the image.
Future telescopes will add onto this legacy, looking deeper and surveying other wavelengths.
The most exciting contributor will of course be the James Webb Space Telescope, due for
launch on March 30, 2021.
With more than six times the collecting area, James Webb will peer back to the earliest
moments in the Universe and see the first stars and galaxies forming in the cosmos.
It’ll watch these early galaxies crashing into each other to form larger and larger
structures.
Oh, and not to mention watching the birth of stars, and the planets orbiting around
them.
But I’m sure there will be a James Webb Deep Field.
I can’t wait to see it.
What do you think?
Let me know your thoughts in the comments.
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