How to Look at Neptune Through a Telescope

Look for Neptune in the months of August, September and October, as "Sky and Telescope" recommends. It is easier to spot in these months.

Use a telescope with a magnification power of at least 200. This is the minimum magnification you need to spot Neptune as a small blue-white dot. The aperture of the telescope--which refers to the diameter of its lens or mirror--must be at least 4 inches or 100 mm, according to "Sky and Telescope."

Use a star chart to find the current location of Neptune, which shifts throughout the season. "Sky and Telescope" has charts to help you spot the planet.

Stand facing south and look for Capricornus low on the horizon, without using your telescope. Utah Skies, an astronomy organization, states that Capricornus lies about 20 to 35 degrees above the horizon. To judge this distance, hold your hand in front of you and spread your fingers wide; this is about 20 degrees. Capricornus is shaped like an upside-down triangle--sometimes called "bikini bottom"--and lies east of Sagittarius, according to Pepperdine University.

Shift your attention to the upper left-hand corner of Capricornus. Position your telescope to hit this point. Above it, look for a steady stream of brightness that is somewhat bluer than other stars. If the dot agrees with your charts, you may have spotted Neptune.