Despite there being hundreds of millions of stars in our galaxy, there are many places on earth where people cannot see these twinkling pin-pricks of light from their homes. Two thirds of American cities, for instance, cannot see the Milky Way from their backyards, according to Chris Luginbuhl, an astronomer with the US Naval Observatory in Arizona.
The more we light up the earth in the evenings, the less chance there is to see stars. This is because as we illuminate our cities at night we are also illuminating the night sky. The light travels upward, reflects off the earth’s atmosphere to create a blanket of light that smothers the splendour of all but the brightest stars.
The dazzling spectacle of starlight is hugely reduced for those living in urban areas where it has been estimated that city dwellers in Europe and America may be able to see around 500 stars compared with darker areas where it is more likely to observe 15,000 stars.
There are techniques that can be used for those dwelling in cities to increase your chances of seeing stars and the Milky Way. Firstly choose your viewing place. In the city, there are buildings that can obstruct the view but on the other hand, they can sometimes be used to block the light pollution of the city, depending on which part of the sky you are observing.
The site should be as dark as possible. If it is safe to use the roof of a building, this can be an ideal place from which to view the skies. City parks, grassy areas and hilly places slightly away from dwellings are also ideal places from which to view the stars. The idea is to try to block as much light as possible. Trees and fences can do this or you might erect some form of shield in your garden to block the light from behind you. Failing this try draping a dark cloth over your head when looking through the eyepiece very much like photographers in history used to do.
There are celestial bodies that are bright enough to be seen through the haze and smog of light pollution and many amateur astronomers are content to be able to observe these from their homes. The Moon and all its different phases, for instance, can often be seen in amazing detail from cities.
Time it carefully if you are hoping to observe Mercury which can only be seen on the horizon in the first hour before sunrise or after sunset. You therefore need a clear view of the skies where the sun is setting or rising to see Mercury. Other celestial objects are better seen when they are at their highest in the sky. After midnight and the early hours of the morning are often the best for observing the skies from the city.
While some stars can be seen by the naked eye, a telescope or a good pair of binoculars will increase your chances of seeing stars in areas where visibility is seriously impaired by light pollution. Eye pieces should have eyecups as these are designed to guard against localized light entering the corner of the observer’s eye.
Other techniques to help urban stargazing is that you should know what you are looking for. Do some research to find out what stars or planets are visible and where and when you might see them. Once you have decided on your observation area, give your eyes a chance to adjust to the dark. Remember that the longer you observe, the more you will see. You might also use a star chart to locate the different constellations.