Twenty-one years ago, NASA launched the Hubble Space Telescope, a time machine that has been captivating people worldwide ever since. Named for revolutionary 20th century astronomer, Edwin P. Hubble, author of the Big Bang theory, the closest we have come to a scientific theory explaining the origin of the Universe, Hubble is a space-based observatory that has transformed astronomy, spirituality, and galvanized even the most casual stargazers among us.
To this day, this observatory in low-Earth orbit continues to provide never-before-seen deep and clear views of the universe. Its images range from the most remote stellar bodies at the beginning of time, to a more localized neighborhood – our own solar system. Hubble is the most celebrated celestial observer since Galileo assembled his first optical instrument to gaze at planet Jupiter, 400 years ago.
A Firefly at 10,000 Miles
Hubble operates from a unique vantage point where no other observer of the cosmos can compete – in orbit around Earth, free of the atmospheric obstacles that cloud even the most powerful land-based observatories. The brainchild of astronomer Lyman Spitzer, Jr. (anyone’s guess why Congress didn’t name it for him), and five decades in the making, the Hubble Space Telescope peers back ceaselessly into space (and time), its uniquely clear and deep views of the cosmos revealing dramatic stories of universal creation and destruction.
Small compared to most telescopes (it could be no bigger than space shuttle Discovery’s cargo bay), Hubble’s mirror is so powerful that the telescope it supports can spot a firefly at ten thousand miles, the distance, roughly speaking, between Sydney and D.C. Eliminate the distortions of our atmosphere, and this emissary from Earth can see – practically speaking – forever.
At its inception, it was said that Hubble’s primary mirror, with no peaks or valleys greater than one-millionth of an inch, was the most perfect ever made. But in what almost turned out to be a cosmic joke of astronomic proportions, a few weeks after its launch on April 24, 1990, scientists discovered that Hubble’s main mirror was anything but perfect. They found on it a spherical aberration, an imperfection one-fiftieth the width of a human hair, meaning that the all-important mirror had been ground into the wrong shape (light from the outer regions of the mirror could not come into focus at the same point as light from the inner regions). Like many of you (more mature) readers, the great Hubble Space Telescope was nearsighted.
The mirror itself was irreparable. But a new camera with other instruments could correct for the aberration. Hubble, like any challenged reader, would need a pair of glasses. In 1991, almost a year after launch, in what was called by many scientists the “miracle mission”, astronauts on the space shuttle Endeavor performed five breathtaking spacewalks, replacing components to correct Hubble’s blurry vision. Subsequent “surgical” missions in 1997, 1999, 2002 and 2009 have kept Hubble healthy enough rewrite the staple of most scientific textbooks – the very books on which scientists and astronomers who built Hubble had earned their PhD’s!
Bodies in Motion
Every ninety-seven minutes, the Hubble Space Telescope circles Earth at a speed of 5 miles per second – fast enough to cross the U.S. in ten minutes. As it travels, Hubble’s mirror captures light and directs it into its several bleeding-edge science instruments, including, of course, a telescope. The large field of view telescope is a solar powered Cassegrain reflector(invented in the early 20th century), and its power, contrary to popular belief, lies not in magnification, but rather in the (corrected) mirror’s ability to capture light.
This captured light is then relayed to the array of impressive instruments that allow scientists to (among other tasks) record the birth of individual stars; photograph and map extremely remote galaxies; study the effects of Dark Matter, the invisible “anti-matter” that theoretically comprises more than 90% of the mass in the Universe; all while capturing wavelength “fingerprints” of observed objects, revealing previously unknown data about their temperatures, chemical composition, density and motion.
The Hubble Revolution
Some of Hubble’s more historic images and discoveries include the breathtaking (and allegedly most popular) “Pillars of Creation” (seen below), a star-forming region in the Eagle Nebula about 6,500 light years from Earth. Light travels at 186,000 miles per second – so you do the math.
In the public domain we, as a species, now own countless snapshots of the celestial life cycle, the stuff that only poets could dream of – the birth and death of planets, galaxies and stars that drives cosmic evolution, a process both violent and beautiful to witness. We can now open a book or turn on our computers to glimpse still-lifes of planets forming from discs of dust around stars; “baby” stars in a nearby satellite galaxy (NGC 346) that have not yet ignited their hydrogen fuel to sustain nuclear fusion – the process that allows our Sun to “shine”; and evidence of much-hyped Black Holes, which are collapsed massive stars with gravitational forces so extreme that even light cannot escape. To think that merely 100 years ago, people had to stand motionless, for an hour, to have their portrait taken, here on Earth.
To give you some cosmic perspective, just a fragment of any of these images, encompassing, say 2.5 light years, is a distance equal to 23 million trips from where you are sitting to the Moon. That’s how grand and all-seeing Hubble’s light gathering mirror is. Consider the Butterfly Nebula (or “bug” nebula, pictured below), a cauldron of gas heated to more than 3,600 degrees Fahrenheit tearing through space at more than 600,000 mph, fast enough to reach the Moon from Earth in 24 minutes. Not a bad commute.
Time Travel for Dummies
Any Star Trek or Lost aficionado can tell you that time travel is a passage through some ill-defined wormhole that allows a lucky (or unlucky) soul to encounter either alternate versions of the past; or more goofily, his or her own self, whether alternate or not, in the past. Never mind that this currently fashionable form of fictive time travel violates the purists’ Grandfather Paradox – that a person cannot encounter their grandparent in the past (let alone themselves) lest they kill their forebear, and thus they themselves would never exist – what passes for real time travel in the astronomer’s world is far more compelling and inspiring than that: much of what we see in the sky no longer exists!
We can only see these dead astral bodies, called ancient white dwarfs, because they were so old when they shone (12 billion years) and far away (16,000 light years) that the light they emitted is only reaching us now. Nothing translates the universal scale of the cosmos – and the wonders that Hubble is capturing in its far depths – more than this.
So next time you look up into the night sky, remember that being alive has given you an extraordinary gift: time travel. You are gazing back in time at cosmic ghosts. And in case you’re planning a really novel adventure, remember that anyone can apply for time on the telescope. Get in your bids now.