Pluto, Ceres and an exciting summer for space exploration: Bob McDonald

Four robotic spacecraft will be exploring alien worlds this summer,each one very different from the others.

The most anticipated mission is the July 14close flyby of Pluto by the New Horizons spacecraft. After traveling for nine years, the small probe -about the size of a pup tent -will make the first-ever close encounter with the dwarf planet. (Pluto was still classified asa planet when New Horizons left Earth in 2006.)

During the one-day encounter, the spacecraft will take close-up pictures of Pluto and its moons, study its atmosphere, look for ringsand basically try to find out everything possible about this distant world, as it whizzes by at 50,000 km/hr.

The craft is traveling so fast that it can't slow down to go into orbit or land on Pluto, so there is only one chance to do the science before it is flung entirely out of the solar system. (You can hear an interview with one of the mission scientists this week on Quirks & Quarks.)

Unfortunately, when it is closest to Pluto, New Horizons won't be sending back pictures to Earth because it will be too busy pointing itself in as many different directions as possible -like a rubber-necking tourist.The best images and scientific data will be stored in the computer memory and played back much later. However, we should see a high-resolution image during the approach to the Pluto system, and another one looking back on the way out.

Don't forget about Ceres

A second dwarf planet that isn't getting much attention is Ceres, which is out among the asteroids between Mars and Jupiter. The Dawn Mission began circling Ceres last March and has already spotted some unusual features. One crater has eight mysterious white spots in it and a pyramid-shaped mountain rises strangely out of what is otherwise a flat area.

Dawn is slowly lowering its orbit, so by August, it will be only 1,450 km above the surface. From that vantage point, it will be able to resolve these and many other features in unprecedented detail.

Also in August, the hugely successful European Rosetta Mission to Comet 67-P will enter its most exciting phase. The comet will make its closest pass by the sun, where ices on the surface vaporize, rise upwards and produce a long, gaseous tail that streams out into space.

Rosetta will be following this actionas the comet swings around the sun, while its lander, named Philae -which just woke up from seven months of hibernation right on the surface of the comet -with be monitoring the action from the ground.

And look at the world around you

While all this action is taking place on other worlds, make sure you take some time to get outside and appreciate this planet. Leave the computers and devices at home and visit a river, shoreline, forest or any piece of nature you can reach. Slow down, take in the environment, listen for insects and birds, turn over some rocks to see what's crawling around underneath, take a close-up look at some of the other creatures and plants that share the planet with us.

The Earth is still the only world we know of (so far) that has life. All the other planets and moons we have seen are really interesting, but not places where we could live without space suits. Earth is small as planets go, surrounded by a thin bubble of air, a thin film of waterand a thin coating of colourful living fuzz.

It's a rare place in this very big universe. Let's get outside and appreciate it.

Have a great summer.