[Telepathic Intruder]

"In order for the Earth to lose heat, we expect it to transfer energy to an object that is cooler.

That's true with conduction and convection, but not radiation. Radiation transfers energy, which heat is a form of. It does not need to transfer to something cooler.

[raybbr]

isn’t space a lot cooler? We are surrounded by a vacuum which, by definition, should be drawing plenty of energy from the planet.

[1FreeAmerican]

Heat is the product of the interaction between radiation and any molecule that can absorb it. Since in space there are no molecules to absorb it the temperature is very cold but you will still get cooked without something to reflect or absorb the energy. There is more energy outside our atmosphere than inside it hence the conclusion that that the earth does not radiate any energy into space - it can only absorb energy. Therefore greenhouse gases do not make our planet warmer because they prevent warm air from escaping into the cooler atmosphere.
Im no physics guy though - just an electrician.