Pluto: Brighter Than You Think

(source: NASA)

 

This artist's concept of the frosty surface of Pluto with Charon and our sun as backdrops illustrates that while sunlight is much weaker than it is here on Earth, it isn't as dark as you might expect. In fact, you could read a book on the surface of Pluto.

What would you see if you stood on the surface of Pluto?

Nobody knows exactly what it would look like--that's one reason the New Horizons mission to Pluto is so exciting. But there are a few things we do know. The sun would be about 1,000 times dimmer than it appears on Earth. Instead of a big yellow disc, the sun would look more like other stars, with one big difference: it would still be much, much brighter than anything else in the sky. Pluto has a thin atmosphere that would scatter the light, but probably not enough to make a bright sky like we see on Earth or Mars.

But it wouldn't be completely dark. In fact, if you stood on Pluto at noon you would have enough light to easily read a book. That's in part because your eyes are very good at automatically adjusting to different levels of light. If you had a camera, to get a clear picture of the landscape you'd want to adjust the settings for a longer exposure time or a wider aperture in order to capture as much light as possible. You'd have plenty of time to work on it: one full day on Pluto takes about 153 hours, and because of its axial tilt and very long seasons, parts of Pluto can remain lit for years at a time.

You can see for yourself how much light there is on Pluto. If you go outside on a clear day a few minutes after sunset or a few minutes before sunrise, that's about how much sunlight there is on Pluto at noon.

The New Horizons team has specifically designed and prepared the spacecraft's cameras for the light conditions at Pluto, so they'll be ready to capture whatever the mysterious dwarf planet and its moons have in store.

What else would affect the light on Pluto?

On Earth, the amount of light you see depends on the weather and other atmospheric conditions. We don't know much for sure yet about what kind of weather Pluto might have. One thing you'd definitely notice in Pluto's sky would be its moon Charon. Pluto has five moons (that we know of so far) but Charon is by far the biggest. It's so large compared to Pluto that instead of Charon going around Pluto like our moon goes around the Earth, Pluto and Charon orbit each other like a double planet. Charon is tidally locked in its orbit with Pluto in such a way that it can only be seen from one side of Pluto, similar to the way we can only see one side of our moon from Earth. If you were on that side of Pluto, Charon would sometimes be very bright in the skies overhead.

In fact, when New Horizons flies by in July it will photograph some areas on the night side of Pluto that will be illuminated only by Charon moonshine.

Pluto: Overview: King of the Kuiper Belt

Browse the latest images from New Horizon's history July 2015 flyby.

Discovered in 1930, Pluto was long considered our solar system's ninth planet. But after the discovery of similar intriguing worlds deeper in the distant Kuiper Belt, icy Pluto was reclassified as a dwarf planet. Findings by NASA's New Horizons in 2015 revealed for the first time how that Pluto is a complex and mysterious world. Information about Pluto and its largest moon, Charon, provide insight into the collision believed to have formed the dwarf planet and moons we see today. 

Astronomer Cyde Tombaugh discovered Pluto by blinking two photographic plates back and forth on a machine called a blink comparator

Dwarf planets may provide the best evidence about the origins of our solar system.

 

Pluto: 10 Need-To-Know Things

If the sun were as tall as a typical front door, Earth would be the size of a nickel and dwarf planet Pluto would be about the size of the head of a pin.

Pluto orbits our sun, a star, at an average distance of 3.7 billion miles (5.9 billion kilometers) or 39.5 AU.

One day on Pluto takes about 153 hours. That's the time it takes for Pluto to rotate or spin once. Pluto makes a complete orbit around the sun (a year in Plutonian time) in about 248 Earth years.

It is thought that Pluto has a rocky core surrounded by a mantle of water ice with other ices coating its surface.

Pluto has five known moons. Pluto is sometimes called a double-planet system due to the fact that its moon Charon is quite large and orbits close to its parent planet.

NASA's New Horizons spacecraft is the first mission sent to encounter the Pluto-system and other members of the Kuiper Belt.

There are no known rings around Pluto.

Pluto has a thin, tenuous atmosphere that expands when it comes closer to the sun and collapses as it moves farther away -- similar to a comet.

Scientists do not think Pluto can support life as we know it. Although, some scientists believe it is possible Pluto could possess a hidden ocean under its surface.

Pluto was considered a planet from 1930, when it was first discovered, until 2006. The discovery of similar-sized worlds deeper in the distant Kuiper Belt sparked a debate which resulted in a new official definition of a planet. The new definition did not include Pluto.