The Major says so, and you have to believe the Major.
Explore the darkness and danger of The Halo 3 Legendary Map Pack – Blackout, Avalanche and Ghost Town. Wander the catwalks and catacombs of Blackout and its vertiginous series of aeries and turrets, illuminated by the chill and baleful glare of a moonlit sky. Avalanche is colder still, and as vast as it is icy. Fly on silent wing through its valleys and caverns. Ghost Town’s ruinous abandonment.
It's 79Mb and will probably be on YouTube in about ten minutes. Go watch it on Live, just for fun.