That may be because these places are very energetic, which makes it difficult to discern orbiting planets using our current observation techniques.

BBC: 'Dirty' stars hint at Sun's future

The current top observation deck at 1, 250 feet is enclosed, but in the original plans it was an outdoor platform where you loaded on and off trans-Atlantic dirigibles parked over midtown.

BBC: At 80, the Empire State Building strikes back

I'd ridden a wind current down to the observation deck and spotted Uberman sitting on the ledge with his legs dangling off the side.

NPR: Excerpt: 'Hero'

With a focus on key topical issues such as marine pollution, exploitation and hazards, chapters range from the history of ocean management to current advances in marine science, observation and management applications, and the international agencies active in co-ordinating this work.

UNESCO: Troubled Waters

The MSPs who made the decisions on free personal care, free concessions and free tuition fees were from all the main parties at different times, so it's not as political an observation as it might look in the current debate.

BBC: Bark and bite from the public��s watchdog

The current report follows years of painstaking research designed to strengthen this initial observation.

BBC: System could warn of solar storms