Brown spots, or hyperpigmentation, don't show up on just naturally freckle-prone people -- they can form on any type of skin during any time of year. But one thing is for sure: they tend to pop up most in the summer, when the sun's skin-damaging rays are abundant.

In the video above, Us Weekly asks NYC-based dermatologist Dr. David Colbert, who has treated the faces of Rosie Huntington-Whiteley and Rachel Weisz, how to prevent dark spots from appearing in the first place, plus what to do when a new one forms.

Dr. Colbert warns that if you see a new dark spot, or an existing one that has an altered appearance, head to your dermatologist to check it out. That kind of sun-care safety plus wearing SPF 30 daily (and reapplying it throughout the day) should help keep spots at bay.

To find out what kind of treatments are best at fading hyperpigmentation, watch the video above!