All you need to know about NASA's Pluto mission

Have you noticed today's Google Doodle yet? Created by Kevin Laughlin, the doodle shows a space probe spinning around a planet. Well the planet is no strange to us. It’s Pluto. 

For decades, school texts said there were nine planets in our solar system with Pluto being the furthest one from the sun. But in 2006, the International Astronomical Union downgraded Pluto from the solar system's ninth planet to a dwarf planet. 

Turns out that was a wrong call. 

Now, scientists with the ‘New Horizon Mission’ -- which is one a long, winding journey across our solar system -- have found Pluto to be 1,473 miles (2,370 kilometers) in diameter,  or about  18.5% that of Earth's, somewhat larger than many prior estimates. Images acquired with the Long Range Reconnaissance Imager (LORRI) were used to make this determination. This result confirms what was already suspected: Pluto is larger than all other known solar system objects beyond the orbit of Neptune.

Measuring Pluto’s size has been a decades-long challenge due to complicating factors from its atmosphere. Its largest moon Charon lacks a substantial atmosphere, and its diameter was easier to determine using ground-based telescopes. New Horizons' observations of Charon confirm previous estimates of 751 miles (1208 kilometres), or 9.5% that of Earth's, across.

(The following graphic presents a view of Pluto and Charon as they would appear if placed slightly above Earth's surface and viewed from a great distance)

Then why are we excited about it?

The reason is NASA's New Horizons spacecraft will fly by Pluto to capture never-before-seen images at close range. After nearly a decade and a travel of 3 billion miles from Earth the unmanned vehicle has reached the dwarf planet. 

Why send @NASANewHorizons for a #PlutoFlyby? Find out as we answer these 4 mission questions https://t.co/5yx6MZMx7j https://t.co/2YPhwjKDjg

— NASA (@NASA) July 13, 2015

No spaceship has ever visited Pluto. The Hubble Space Telescope can't even give scientists an accurate reading of the Pluto’s size. But New Horizons can. Data the spacecraft sent back in recent days shows astonishing details, revealing that methane and nitrogen ice cover Pluto's north pole, and that it could also be much larger than estimated.

Why is this operation so special?

Pluto and the other objects in the Kuiper Belt are considered remains of the very first days of the solar system. They've also stayed very cold for the past 4.6 billion years, meaning they haven't changed as much as objects closer to the sun. By examining the atmosphere and composition of Pluto and its moons, scientists may learn things that can inform our models of the formation of the solar system.

Then what's the Kuiper Belt?

It's the farthest region of our solar system, discovered in 1992, and it contains the cold debris of our system's formation. It is filled with hundreds of thousands icy bodies like Pluto and trillions of comets, says NASA. Planets form by the joining of several masses. 

.@NASANewHorizons will go dark tomorrow before its #PlutoFlyby. Why? Watch Pluto in a Minute! http://t.co/HyxaTH6Rq0 https://t.co/TUR8WxzX3J

— NASA (@NASA) July 13, 2015

But, the Kuiper masses never joined, which means scientists can study these 4-billion-year-old forms to learn about the beginning of Earth's solar system. As far as scientists know, none of the masses support life.
 

Can I watch it fly by the Pluto live?

Well, nobody on the third rock from the sun is going to see New Horizons fly by the Pluto live. But thanks to the power of planetary physics, NASA’s visualization team has loaded the flight plan into their Eyes On The Solar System app.

If everything goes as planned, mission control will get a small packet of data sometime around  9 pm ET (about 6 a.m. IST) on Tuesday.

Keep following NASA's twitter feed for updates.