Whenever the subject of mosquito control comes up, someone gives a fervent argument for installing purple martin houses and bat houses. Stores that cater to bird enthusiasts often tout the purple martin houses as the best solution for keeping your yard mosquito free.
A short period comet is conventionally defined as a comet having an orbital period of less than 200 years. What is the maximum possible aphelion distance for a short period comet with a perihelion of 0.5 AU? Where does this place the comet relative to the outer planets? (3)
The semi-major axis of Pluto's orbit varies between about 39.3 and 39.6 au with a period of about 19,951 years, corresponding to an orbital period varying between 246 and 249 years. The semi-major axis and period are presently getting longer.