The New Horizons spacecraft has taken its first color image of Pluto and its moon Charon.
Past Pluto
New Horizons is a small spacecraft on its way to Pluto. It will make its closest approach next Summer. To get to Pluto in a reasonable time, the spacecraft is heading there at high speed. This means it will zip past Pluto and head out into the Kuiper belt. While Pluto is a worthy goal, it would be nice if New Horizons could observe other objects in the outer solar system. But given the high speed of the spacecraft, and the low mass of Pluto, there isn’t a good way to use the planet’s gravity to change direction towards a particular Kuiper belt object (KBO). Basically, New Horizons is on a straight trajectory out of the solar system. So instead astronomers have been searching for KBOs that are along the path of New Horizons, and they’ve found some candidates.
Approximate Pluto
Just how big is Pluto? The answer is we aren’t entirely sure. We know the diameter is between 2,300 and 2,400 kilometers, but it’s hard to pin down beyond that.
Forever Alone
A plutino is an asteroid-sized body that orbits the Sun in a 2:3 resonance with Neptune. They are named after Pluto, which also orbits the Sun twice for every three orbits of Neptune. It is thought that Pluto and the other plutinos were clustered into this resonance during the migration of the outer planets during the early solar system.
Newer Horizons
The New Horizons spacecraft is on its way to Pluto. It will fly-by the dwarf planet in July 2015. The spacecraft will have far too much speed to stay near Pluto, so after its visit the craft will continue its journey away from the Sun. Given that Pluto marks the inner edge of the Kuiper belt, it would be nice if New Horizons could explore other Kuiper belt objects.
Size Matters
With the recent post on Pluto, one of the questions that came up was about imaging Pluto itself. Currently the best image we have of Pluto is one taken by the Hubble telescope. It is a blurry smudge of shading without any real detail. At the same time, Hubble has taken extremely detailed images of distant objects, such as the ultra deep field. So how is it that Hubble can image distant galaxies in detail, but can’t get a detailed image of Pluto? It all comes down to an object’s size. Not its actual size, but its apparent size.
Sharing is Caring
With the New Horizons spacecraft on its way to Pluto, and scheduled to flyby the dwarf planet in 2015, there is a growing interest in this distant world. Much of this focuses on aspects of the planet that might be important for the flyby. A while back I talked about how computer simulations of Pluto and its largest moon Charon showed that they likely formed through a large collision, and as a result New Horizons should find additional plutonian moons.
Guardian of the Galaxy
Many people have an emotional attachment to the planet, and feel somewhat offended that the mean astronomers have declared the tiny world to be not a planet. So what about Pluto? Well, it turns out we now know a great deal more about the planet than we did when you were little, and we’ll soon know even more.
Alas, Poor Ceres
In 1801 a new planet was discovered in our solar system. Just twenty years earlier the planet Uranus was discovered beyond the orbit of Saturn, and was the first planet discovered since the dawn of civilization. This new planet was named after the Roman goddess of agriculture, Ceres.