This Tuesday will mark a historic event in planetary exploration, as after nine years and three billion miles of travel the New Horizon probe becomes the first man-made object to do a close fly-by of the planet Pluto. (And yes, I still consider it a planet!)

It should be exciting to see what images and data it returns to Earth on the day. However even now as it makes it approach it is sending back a lot of fascinating information. The first images of the surface have already been mapped in GoogleEarth, and can be downloaded here. 

The New Horizon cameras have also sent back some great images of geological features on the surface. There appear to be linear marks that may correspond to long cliffs, as well as a circular feature in the southern hemisphere that appears to be a huge crater. Also of some note is a bright heart-shaped object in the northern region and a darker area in the southern region that are not quite visible yet, but should be observable during Tuesday's flyby. No one really knows what they are yet, but there are already many theories and speculations.

Whatever we get to see, Tuesday should be an interesting day in astronomy and astrophysics. Those who are interested can follow the mission on Twitter at #PlutoFlyby or on Facebook at https://www.facebook.com/new.horizons1.