ASA's New Horizons spacecraft is about to show us an alien world for the first time. At 7:49 am ET today,

the probe became the first spacecraft to fly by Pluto.

This is a really big deal.

Related NASA's New Horizons mission to Pluto, explained

Inside New Horizons: What it's like to conduct a 9-year mission for a 3-minute flyby

New Horizons has been en route for nine years, traveling more than 3 billion miles. The flyby was over in a

matter of minutes, as the probe frantically took hundreds of photos and collected data on Pluto's

atmosphere, geology, and moons. All this data will be enormously valuable to scientists as they seek to

understand our solar system and how it formed billions of years ago.

But it'd be a mistake to think that this mission is only exciting for scientists. New Horizons embodies a

fundamental characteristic of our species: our urge for exploration, our desire to see a new world simply

because it's there. It represents the best of humanity, the heights of what we can accomplish through

ingenuity, focus, and cooperation.

More than anything, this mission is about broadening our horizons taking in just a little bit more of the

impossibly vast universe we live in.

1) We've never seen Pluto before

Pluto feels familiar. It's easy to imagine the small, frigid rock, millions of miles from the sun and covered in

ice.

But what you're picturing in your head when you think about Pluto is probably an artist's illustration. Until

very recently, we didn't even know exactly what color it was and the best photos we had of Pluto looked

like this:

(NASA/ESA/M. Buie)

Pluto, as seen by the Hubble Space Telescope in 2010. (NASA/ESA/M. Buie)

New Horizons is going to change that in a very big way. Already, as it's closed in on Pluto, it's given us way

better photos than ever before:

Pluto, as seen by New Horizons the day before the flyby. (NASA-JHUAPL-SWRI)

But this is nothing compared to what we'll see starting Wednesday, when the first photos trickle in. As

Alan Stern, the mission's principal investigator, said in April, "Were going to turn points of light into a

planet and a system of moons before your eyes."

The high-resolution photos to come will give us detailed topographical maps, just like those provided by

the satellites that orbit Earth. They could reveal mountains, ice caps, volcanoes, or even an ocean of liquid

water under the ice. "Who knows what kind of bizarre things we'll find up close?" Stern said.

2) This is a staggering technological achievement

It's hard to appreciate just how difficult it is to send a spacecraft to Pluto. But think of it this way:

because it's so incredibly far away, it took New Horizons nine years to cover the 3-billion-mile trip there

which means the craft is using decade-old technology, traveling a route that was calculated years ago.

New Horizons' trajectory through the solar system. (JHU/APL)

Despite this, NASA engineers managed to get the tiny probe about the size and shape of a grand piano

to an incredibly precise spot in space, using Jupiter's gravity as a slingshot to accelerate it outward and

a few thruster burns over the years to keep the probe on track.

Along the way, they had to worry about potentially damaging debris nearby Pluto as well as a scary

software glitch this past weekend, which was, thankfully, resolved. Finally, New Horizons flew within 7,750

miles of Pluto, coming closer than its moons.

(JHU/APL)

Pluto's flyby trajectory.

Because New Horizons is traveling at such a high speed (about 31,000 miles per hour) and can't slow down,

the flyby was over in a matter of minutes forcing it to collect all its data in a tiny window of time.

And receiving all that data will be another huge challenge. Because New Horizons is so far away, it takes

about 4.5 hours for any data it sends back to reach Earth. And the signal is so faint that NASA has to use

200-foot-wide radio dishes (one each in Australia, California, and Spain) to pick it up. This means an

extremely low rate of data transmission: about 1 kilobit per second, more than 50 times slower than a 56k

modem from the '90s. It takes more than 42 minutes for New Horizons to fully transmit an image that's

1024 pixels wide.

3) New Horizons will help us better understand the whole solar system including Earth

(NASA-JHUAPL-SWRI)

Pluto and Charon, photographed by New Horizons on July 8 from 3.7 million miles away.

One of the reasons scientists want to learn more about Pluto is that it likely formed at the same time as

the rest of our solar system, from the same materials. What's more, it likely formed much closer in to the

sun going through the same early stages of growth as Earth and the other rocky planets before being

flung outward billions of years ago.

All the data collected on its geology, atmosphere, and moons will help scientists refine their ideas about

this early era in our planet's history. "We know that the Earth went through the stage of growth that Pluto

stopped at," Stern told me. "This will help us connect the dots."

4) This mission will remind you how vast space really is

(NASA/JPL)

Earth, as seen by the Voyager spacecraft, from more than 4 billion miles away.

We spend our entire lives on the surface of Earth so it's hard to really grasp how far away Pluto truly is

from us.

But as an analogy, think of Earth as a basketball. By comparison, Pluto would be a little larger than a golf

ball. But if you wanted to keep the scale constant, you'd have to put that golf ball incredibly far away: 50 to

80 miles (depending on its location in orbit). This mission, like many activities in space, is a good reminder

of how vast our corner of the universe is and how absurdly tiny our entire earthly realm of experience is

by comparison.

And it's not just the size of space that boggles the mind. It's also the timescale on which everything

occurs. Pluto takes 248 Earth years to orbit the sun. To put it another way, the entirety of US history has

occurred during a single Plutonian orbit. The last time Pluto was in its current position in 1768

humans were totally unaware of its existence (it was discovered in 1930). We hadn't invented aviation, let

alone spaceflight.

(NASA/New Horizons)

All of which is to say: It's pretty amazing that this time around, Pluto will be visited by a tiny robot sent by

a curious species of apes 3 billion miles away. A lot can change in a single orbit.

5) This is the first time in a generation we're seeing a new planet

(JHUAPL/SwRI)

An illustration of New Horizons, next to Pluto and its moons.

Since the dawn of the space age, we've been striving to explore our solar system, sending spacecraft to

each of the planets in turn: Venus and Mars in the 1960s, Mercury, Jupiter, and Saturn in the '70s, and

Uranus and Neptune in the '80s. These probes showed us entirely new worlds, revealing beautiful moons,

rings, atmospheres, and landscapes.

There's since been a generation-long gap. Many people (myself included) aren't old enough to remember a

moment of such pure exploration, of seeing a planet that no one had seen before. On Tuesday, though,

we're once again going to see a new world for the first time.

But in a sense, this is a bittersweet achievement, because it'll also be the last time. Whether Pluto is

officially deemed a planet or not, this mission completes humanity's initial tour of the traditional set of

nine planets in our solar system. Savor this moment, because, as Dennis Overbye puts in an excellent New

York Times column, "None of us alive today will see a new planet up close for the first time again."

6) We won't get many more missions like this for a while

(NASA/JPL-Caltech/SETI Institute)

There's a mission to Europa planned, but it won't reach the moon for a decade or more.

The past few decades have been filled with all sorts of fascinating missions to the planets, moons,

asteroids, and comets of our solar system uncrewed probes sent every few years, run by trained

scientists, and supported by government funding.

But the sad truth is that this era is largely drawing to a close. As David W. Brown writes in an article on

the dark future of American space exploration, "There is nothing budgeted in the pipeline to take its place.

Yesterday invested in today. But we are not investing in tomorrow."

This is the result of cutbacks to NASA's planetary exploration budget. The OSIRIS-REx probe will launch

next year, to travel to an asteroid and bring back a sample, but it won't return until 2023. Meanwhile, a

mission to Jupiter's moon Europa is in the works, but it likely won't be launched until 2025 at the earliest,

and wouldn't reach Europa until the 2030s.

In other words: Enjoy this mission. It's going to be a while before any NASA probe visits a new world.

7) Space isn't "somewhere else" it's where we live

(NASA)

Our thin atmosphere.

Most people think of space as some distant, irrelevant place a setting for sci-fi movies and astronauts,

but one that has nothing to do with our actual lives. Seen in this light, visiting a new dwarf planet isn't

particularly meaningful or exciting.

But this isn't the right way to see space at all. Space is where we live.

Earth is a planet in space, just as Jupiter and Mars are. There's no magical glass barrier 62 miles above

our heads (the altitude commonly accepted as the boundary with space) separating us from the rest of

the universe, any more than there's one at the top of Venus's atmosphere excluding that planet's surface

from space, too.

And we live much closer to what we commonly think of as "space" than you may realize. If Earth were the

size of a basketball, our entire atmosphere the layer of gas separating us from space would be about

the thickness of a pillowcase. In the grand scheme of things, we're already there.

This is why asteroids can come down and hit us anytime, and why space weather can disrupt our

telecommunications equipment and power grid. It's why exploring our solar system matters, just as

exploring Earth's surface does. And it's why all of us should be excited about seeing a new alien world

just as we'd be excited about visiting, say, an entirely new continent on Earth for the first time.

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