Astronomers eagerly await the launch of the $8 billion James Webb Space Telescope.

It will see back in time farther than any space telescope ever has before—back to the first light following the big bang.

It will watch the first stars and galaxies form.

And it will hunt for distant habitable planets by peering into their atmospheres.

Expectations are high for the science that will come from the $8.7 billion James Webb Space Telescope—the successor to the Hubble Space Telescope. The telescope's four main science instruments are now all in one place, as are its 18 mirror sections. When assembled in space, they will create the largest orbiting mirror ever seen.

This long-awaited coming together is taking place in a vast clean room at the Goddard Space Flight Center in suburban Maryland. The last pieces have arrived, and now the two- to three-year task of assembling the telescope has begun.

On Monday, NASA Administrator Charles Bolden, Senator Barbara Mikulski, Senior Project Scientist and Nobel laureate John Mather, and the Webb team celebrated this milestone. And, with equal enthusiasm, they anticipated the science that will come in once the Webb telescope is in orbit, about one million miles from Earth.

With a mirror six times larger in area than the Hubble's, the Webb telescope's possibilities are dramatic:

1. The James Webb Space Telescope is designed to see to the time when stars began to form in the universe.

Astronomers put that time at about 300 million years after the big bang, the period when the universe emerged from its dark ages. The Hubble has been able to see back to 800 million years after the big bang, an unprecedented feat but considerably less than the capability of the Webb telescope.

The first stars in the universe are believed to have been 30 to 300 times as massive as our sun and millions of times as bright. They would have burned for only a few million years before dying in tremendous explosions, or supernovae. The Webb will be able to detect the earliest of these explosions.

2. The Webb can peek inside galaxies.

The Hubble and Spitzer Space Telescopes have already identified many tiny galaxies that were pumping out new stars at a surprising rate more than 13 billion years ago. These galaxies are only one-twentieth the size of the Milky Way, but they probably contain a billion stars crammed together.

The Webb's large mirror is designed to see longer wavelength, invisible-to-the-eye infrared light, which can be used to see farther and to see through thick cosmic dust. This means the telescope will be able to see into the star-creating centers of galaxies as never before.

Webb telescope officials describe their goal as learning about the first galaxies when they were just babies. The Hubble telescope has been looking at toddlers.

3. Scientists now are convinced that each galaxy has, at its center, a supermassive black hole.

The Webb will test why and how these monster black holes came to exist. A favored theory says that the early massive supernovae spewed out chemical elements newly formed in the first stars before they collapsed into black holes or were destroyed.

The newborn black holes are theorized to have then consumed the gas, dust, and stars around them, becoming extremely bright objects called mini-quasars. Mini-quasars are suspected to have grown and then merged to become the huge black holes found in the centers of galaxies.

Understanding the connection between newly formed galaxies and the supermassive black holes at their centers would be an enormous breakthrough in astronomy.

4. The Webb will search for signs of extraterrestrial life.

Using the Webb telescope's spectrograph, scientists will be able to analyze the atmospheres of the billions of exoplanets now understood to orbit stars in the Milky Way. Depending on what chemicals are identified, researchers can come to conclusions about the likelihood of Earth-like conditions. The presence of large amounts of oxygen or ozone in the atmosphere, for instance, would strongly suggest that life was present on the planet.

"We'll be able to do so many things with the Webb that were never possible before," Mather said at the Goddard gathering. "It will revolutionize astronomy and, potentially, our understanding of the universe."

The Webb telescope is scheduled to launch in 2018 from the European Space Agency spaceport in French Guiana, and will settle at a point about four times farther from the Earth than the moon. Fifteen nations have contributed to the effort, and their scientists will be able to observe and discover alongside NASA's scientists.

Two New Space Discoveries Have Rocked the Science World — Each Will Be a Game Changer

The news: Two hot discoveries are rocking the way astronomers, physicists, and space scientists view the universe — and they're truly something.

The first is intense: Scientist John Bradley from the Lawrence Livermore National Laboratory in California took a microscopic look at the interplanetary dust particles lurking at the edge of Earth's stratosphere. He found minuscule bits of water hidden in the <25 micrometre flakes of dust, which are already half the width of a single human hair. New Scientist explains:

"The dust is mostly made of silicates, which contains oxygen. As it travels through space, it encounters the solar wind. This stream of charged particles including high-energy hydrogen ions is ejected from the sun's atmosphere. When the two collide, hydrogen and oxygen combine to make water."

Scientists have also previously found carbon and organic compounds in star dust.

According to researcher Hope Ishii, who was involved in the study: "The implications are potentially huge. It is a particularly thrilling possibility that this influx of dust on the surfaces of solar system bodies has acted as a continuous rainfall of little reaction vessels containing both the water and organics needed for the eventual origin of life."

The same dust is expected to be found across other solar systems as well.

In other words, the ingredients for life are likely spread throughout the universe, making it that much more possible humanity is not alone.

And in another stunning discovery: cosmologists from the University of California, Santa Cruz, and the Max Planck Institute for Astronomy in Heidelberg might have just viewed dark matter for the first time, as pictured above.

As BBC News explains:

"The cosmic web suggested by the standard model is mainly made up of mysterious 'dark matter.' Invisible in itself, dark matter still exerts gravitational forces on visible light and ordinary matter nearby.

"...  Cosmology theory predicts that galaxies are embedded in a cosmic web of "stuff", most of which is dark matter. Astronomers obtained the first direct images of a part of this network, by exploiting the fact that a luminous object called a quasar can act as a natural "cosmic flashlight."

Why is this so important? Their research adds significant credence to the standard model of cosmology, which predicts that as the universe expands and grows, it forms clusters and nodes under the influence of gravity, like a gigantic universe-spanning web. Invisible dark matter still forces gravitational influence on visible light and normal matter nearby.

According to the scientists, glowing hydrogen lit up by the quasar being studied traced out an "underlying filament" of dark matter attracted to it by gravity.

"We now have very precise measurements of the amount of ordinary matter and dark matter in the Universe," said Prof. Alexandre Refregier of the ETH Zurich, who did not contribute to the study.

"We can only observe a fraction of the ordinary matter, so the question is what form the remainder takes. These results may imply that a lot of it is in the form detected here."

Hell yeah, Science. Illuminating the universe since 1500 B.C.

If you were ever worried that you won't live to see the really cool stuff science discovers, rest easy. It's happening around you every day.