Wikipedia
A Nanolight is an Australian class of ultralight powered aircraft. It was originally defined as a Powered Hang Glider with an empty weight, including both wing and power system, of less than . A Nanolight may be launched on foot or using a wheeled undercarriage.
The term was coined in about 1998 by Australian John Reynoldson to differentiate this class of aircraft in Australia from the better known " microlight" class of weight shift ultralights, which weigh up to and must be registered in that country.
Nanolights are somewhat slower than purpose-built microlights. Because they are so light, they are often used for thermal soaring. The engine is used to launch the aircraft to a safe altitude and to find a thermal. It is then turned off and the pilot uses thermal lift alone to gain altitude.
Nanolights are popular with hang glider pilots who use them to get flying time without the logistical problems attendant with finding a suitable hill and risking not finding a thermal after launch.