5 things you need to know about the Pluto flyby
We've made it to Pluto by NASA's calculations, the last stop on a planetary tour of the solar system a half-century in the making.
The moment of closest approach for the New Horizons spacecraft came at 7:49 a.m. EDT Tuesday, culminating a journey from planet Earth that spanned an incredible 3 billion miles and 9 1/2 years.
The flyby is the final destination on NASA's planetary tour of the solar system, which began more than a half-century ago.
Here are the 5 things you need to know about Tuesday's Pluto flyby:
1 - FLYBY TIME 7:49 A.M.: The 3 billion-mile journey from Cape Canaveral, Florida, culminated Tuesday at 7:49 a.m. EDT. That's when the spacecraft flew past Pluto at 31,000 mph. Watch NASA's LIVE COUNTDOWN COVERAGE here: http://www.nasa.gov/multimedia/nasatv/index.html
2 - FIRST A PLANET, THEN IT'S NOT: Pluto was still a full-fledged planet when New Horizons rocketed away in 2006, only to become demoted to dwarf status later that year.
3 - WE WON'T KNOW UNTIL LATER: The spacecraft was too busy taking photographs and collecting information to "phone home." A confirmation signal is expected at around 9 p.m. EDT.
4 - TRACK THE PLUTO FLYBY HERE: See where NASA's New Horizons spacecraft is ahead of the flyby: http://pluto.jhuapl.edu/Mission/Where-is-New-Horizons/index.php
5 - YOU CAN SEE NEW IMAGES HERE: Some great images have already been sent back - you can see them here: http://pluto.jhuapl.edu/soc/Pluto-Encounter/index.php
New Horizons has already beamed back the best-ever images of Pluto and big moon Charon. Pluto also has four little moons.
"The Pluto system is enchanting in its strangeness, its alien beauty," principal scientist Alan Stern told reporters Monday.
Discovered in 1930, Pluto is the largest object in the so-called Kuiper Belt, considered the third zone of the solar system after the inner rocky planets and outer gaseous ones. This unknown territory is a shooting gallery of comets and other small bodies.
An extension of the $720 million mission, not yet approved, could have New Horizons flying past another much smaller Kuiper Belt object, before departing the solar system.
Johns Hopkins University: http://pluto.jhuapl.edu/
The Associated Press contributed to this report.