Dear Tom,
I have recently heard about “rogue planets” wandering through the Solar System. What is the story?

Ingred Barter, Rockford

Dear Ingred,
One hundred billion, perhaps more, so called “rogue planets” may be wandering through the Milky Way (not the Solar System). Most planets (like the Earth) revolve around stars (the way Earth revolves around the sun), but many other planets wander freely through space and are not bound to a star. The existence of rogue planets has been known for a long time but they cannot be seen because they do not emit light. However, a revolutionary new space telescope to be launched by NASA in 2025 will probably be capable of seeing rogue planets in our part of the Milky Way. This will open the door to amazing possibilities.