Blast off.

The most powerful space telescope ever built has successfully launched off the planet. The James Webb Space Telescope (JWST) — which will peer into the deep cosmos at the first galaxies and stars — is now en route to its observing position, 1 million miles from Earth.

The prized astronomical instrument launched from Europe's Spaceport in French Guiana at 7:20 a.m. ET on Dec. 25. Launching from the equator, where Earth's spin is the fastest, gives heavy payloads an extra kick into space.

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It all unfolded without a hitch after numerous delays, including a last-minute weather-related hiccup that disrupted a Dec. 24 launch just a couple days prior. While cloudy skies obscured the visuals a bit as the Ariane 5 rocket soared into the sky, the host of NASA's live stream said the launch "was as flawless as you can imagine."

About 28 minutes after the launch, cheers erupted in NASA's mission control center as the JWST completed its final separation from the rockets that brought it to orbit. Just minutes after that, the telescope powered on as NASA's team on the ground took control.

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The telescope will pass the moon in a few days, and then begin to unfurl its tennis court-sized sunshield. The giant shade will block heat and light (emanating the sun, Earth, and moon) from interfering with JWST's deep-space observations. The unfurling is a critical part of the operation, though a profoundly ambitious one involving the release of over 100 pins, extended booms, and other moving parts. In addition to the sunshield, the telescope's large, hexagonal mirrors must properly fold into place, too. In sum, after leaving Earth, JWST will "begin the most complex sequence of deployments ever attempted in a single space mission," explained NASA.

If everything works as planned, JWST — a collaboration between NASA, the European Space Agency, and the Canadian Space Agency — will start its cosmic science operations in around 160 days.

SEE ALSO:Dramatic NASA video shows James Webb telescope's extremely ambitious space maneuver

Astronomers have grand designs for the over $10 billion telescope:

• Looking into the deep past:JWST's giant mirror, at over 21 feet in diameter (over 2.5 times as wide as Hubble's), will capture bounties of light, allowing it to see the farthest, faintest light in the cosmos. In an ever-expanding universe, this means looking back in time at light that's too far off for other telescopes to see. The immensely distant light from the first stars and galaxies is over 13.5 billion years old. "We're looking back in time," Christine Chen, an astronomer at the Space Telescope Science Institute, an organization that will run JWST, told Mashable.

• Seeing the unseeable: Giant swathes of the universe are obscured by thick clouds of dust and gas, sometimes the cosmic leftovers of exploded stars. JWST, however, is specialized in viewing light (infrared light our eyes and normal telescopes can't see) that slips through these obscuring clouds. In doing so, JWST will reveal stars and objects currently hidden beyond the dust. "It lifts the veil," Jean Creighton, an astronomer and the director of the Manfred Olson Planetarium at the University of Wisconsin–Milwaukee, told Mashable.

• Wild exoplanets: During JWST's first year of operation, scientists will use a quarter of its time (that's a lot!) to view planets in other solar systems, called "exoplanets." The telescope's specialized instruments will analyze what their atmospheres are composed of, and perhaps find similar environments to Earth.

An engineer elevated above the James Webb Space Telescope. Its side mirrors are folded in.Credit: NASA / Chris Gunn

Now that JWST has made it into space, after years of delays, NASA and observers are wishing it a successful deployment in the coming month. Unprecedented views of the universe, and unprecedented science, are riding on it.

"Everyone's crossing their fingers," Jason Steffen, an assistant professor of physics at the University of Nevada, Las Vegas who researches exoplanets, told Mashable.

With additional reporting by Adam Rosenberg.