SOLAR SYSTEM SIGHTS
In the past, many entry-level telescopes came with "sun filters" that screwed into an eyepiece. These filters are very dangerous and should never be used. Thankfully, they are rarely supplied today.
The only safe way to view the Sun directly through a telescope is with a filter that covers the entire front aperture of the scope. Mylar filters are the least expensive and are available in sizes to fit most telescopes. They produce a blue-tinted view of the Sun. Glass filters coated with metal show a natural-looking yellow Sun, but cost about 50 percent more. Both Mylar and glass filters give "white-light" views of features such as sunspots and faculae. To see towering prominences on the edge ot the Sun, however, you need a Hydrogen-alpha solar filter. Unfortunately, these can cost as much as a good telescope.
Colored filters can accentuate particular features on the planets: a green filter brings out Jupiter's Red Spot; a red filter improves views of the elusive dark markings on Mars. A set of four to six colored glass filters often costs no more than an eyepiece. An even less expensive option is to purchase colored gelatin filters from a camera store.