Mars: Hellas Planitia. The largest visible impact crater in the Solar System is Hellas Planitia on Mars, a giant depression with a floor over seven kilometres (4.3 miles) below the Martian surface.
Dimensions. The recommended size for one parakeet is 25 inches tall and 25 inches deep. To house two birds comfortably, you should double that cage size to make it at least 50 inches tall and 50 inches deep.If you can afford it and have enough space, opt for a bigger cage.all cages work best for parakeets. This type of bird really likes to fly around and hop from place to place. If you can, choose a cage that exceeds the height recommendation of 50 inches.
The standard minimum cage size recommended by bird professionals is 12- by 18- by 18-inches for a single bird. This cage size is fine if your budgie is outside of the cage most of the time, but if you have a cage-confined budgie, it's going to be much too small to keep your bird happy and healthy.