The allure of high altitude stargazing
Standing under a brilliant canopy of stars at night is one of the most inspiring ways to experience the beauty of nature. The accumulated glow of the summer Milky Way overhead can be bright enough to illuminate the ground. If you ask any backcountry mountain traveler if the stars are brighter from camp the answer is always yes. The reason is altitude. The higher you are the less atmosphere we look through, causing the incoming light from space to be brighter than seen at sea level.
Earths atmosphere can be detected up to a height of 1,000 kilometres. Although invisible, this mass of air above us exerts pressure down on us. Air pressure measured at sea level is10.9 kg per square metre (1 Bar) or 14.5 lbs per square inch. The force on 1,000 square centimetres (a little larger than a square foot) is about a ton! At an elevation of 2,500 metres (8,200 feet) air pressure is approximately 1/4 less than at sea level. Sky watching from this elevation the observer looks through less obstructing air, stars and planets are brighter and clearer. The subtle colours of stars are much more apparent too. The layer of air around our planet affects all incoming sources of energy from the cosmos, the higher you are the better the view.
The radiation we receive from astronomical objects is composed of other forms of emissions besides light. Stars, nebulae and galaxies emit energy in a broad spectrum called electromagnetic radiation. This radiation is composed of radio waves, microwaves (TV, FM, radio and radar), infrared waves (radiant heat), visible light, ultra violet, X-rays and gamma rays. Each form of radiation varies by the size of their wavelengths. Gamma rays are the most powerful and have the shortest wavelength, radio waves are the weakest form of electromagnetic radiation with long wavelengths. Astronomers today observe the universe by studying all the wavelengths of the electromagnetic spectrum but some are not visible from Earths surface.
Earths atmosphere selectively absorbs portions of this radiant energy coming from space. Gamma ray, X-ray and ultra violet radiation, mainly from the sun, are almost totally blocked by atmospheric absorption. These kinds of radiation are lethal to life on the planet. Our atmosphere acts as a powerful filter blocking these deadly forms of energy from reaching Earths surface. Visible light experiences a similar yet less hindering effect. Air, by itself, is almost completely transparent, but suspended particles of dust, smoke, water droplets, ice crystals and air molecules reflect light. This degrades and dims the light emitted by a celestial object as seen from Earths surface. All of the worlds prime astronomical observatories are located at high altitude to try to escape the atmospheres obstructing effect.
The ideal place to look at the stars is from space, where there is no air to look through. Orbiting telescopes have the ultimate view from the vacuum of space. The Hubble Space Telescope took full advantage of its vantage point from earths orbit last fall while taking the deepest picture of the universe ever made. After 400 orbits and an exposure time of 11.3 days the orbiting telescope produced an image that showed 10,000 galaxies, some at a distance of 13 billion light years. This image, which surpasses the original "Deep Field" photo, captured galaxies shapes and sizes as they appeared only 500 million years after the Big Bang!
Southwestern British Columbia has pristine night skies, the stargazers I know from around the continent would leap at the chance to see our starry nights. If you cant get into orbit try reaching a high altitude observing sight, you will experience the ultimate in stargazing.
For more information on summer star parties and events contact John Nemy at http://www.nemy.com/
Monthly Bird Walk The next bird walk will take place Saturday, June 5th. Join Whistler experts in the monthly update of our feathered locals and migrants. For details, contact Michael Thompson at 604-932-5010
Naturalists Speaker Series Stargazing in Whistler from High Altitude with John Nemy of The Pacific Observatory, Whistler. Event will take place Tuesday, June 8th at 7:30 p.m. at MY Place (doors open at 7 p.m.). Admission by donation, children free.
Nature Walks Meet Dan McDonald at 6 p.m. Wednesday, June 9th at the Lost Lake Ticket Booth for a tour of the Lost Lake Nature Trail.
Pemberton Bird Walk at One-Mile Lake The walk leaders are the five crack birders from the annual Breeding Bird Survey. Meet at 8 a.m. Saturday, June 12th in the parking lot. For details call Bob Brett at 604-932-8900.