Jul 28, 20195 min read

What does the night sky actually look like?

Updated: Jan 24, 2020

Contrasting night skies/ Modified; original photo from Josh Hilld @ Unsplash/ See description for original photo link

A clear night sky is a thing of beauty. No matter where you live on the planet, when you look up, a sense of mystery claims your curious mind, and you lose track of time. It once served as a muse to the ones who filled endless pages with inspiring words, a means to talk with the universe for the ever-curious ones, and for the ones who wandered in the night, it was the device that guided them home. The night sky offers that same ethereal beauty even today, and we still are enchanted by it. But it's not just us. Numerous bird species[1] use the night sky for a variety of purposes, the most prominent being navigation. However, the sky has been changing. The night sky of today is very different from what our ancestors would have witnessed in the hearth of their warm fires, which in fact would also have been different from what the dinosaurs must have encountered millions and millions of years ago. This got my mind working, so I asked myself, what does the night sky really look like?

View from different hemispheres

Earth doesn't have a constant sky because it is constantly moving. Due to this motion around the sun, the stars, which are light years away from us, appear to move in the night sky from east to west just like the sun does. The milky way has more than 100 billion stars[2], but a major portion of them are not visible to us through our unaided eyes. The number of stars that we see in the sky also depends on where we live. Earth is an oblate spheroid made up of two hemispheres, the northern one which consists of the majority of landmass on the planet, and the southern hemisphere which consists of a chunk of South America, an approximate half of Africa, the entirety of Australia, and the icy sheets of Antarctica as well.

This geography makes it impossible for a person living in the southern hemisphere to see stars like the northern star, which lies atop the north pole. For the same reason, Alpha Centauri is only visible in the southern hemisphere. However, people living close to the equator in the northern hemisphere might be able to glimpse at it when the star system reaches its highest point above the southern horizon. A person living close to the equator is also fortunate to see the beauty of the milky way, which people close to the poles cannot witness.

A view of the Milky Way from Australia/ Photo by Alistair MacKenzie @ Unsplash. See link under sources.

Sometimes the cosmic light that sheds upon the planet is blocked by hindrances like clouds, fogs, and mist. But even when these entities are not around, most of us are unable to see the picturesque beauty of the night sky. According to the UN, more than half of the global population lives in cities, and in cities, there occurs a phenomenon, which is far more of a barrier in viewing perfect night skies than clouds or fogs. It is called light pollution, and most of our cities are drowned in it. Light pollution[3] is caused due to extensive usage of artificial lights, and it has huge impacts, not just on the night skies, but on the ecosystems as well. Light pollution instills damage to nocturnal organisms like bats whose lives are codependent on darkness.

Light pollution in cities

A measure of 22 magnitudes per square arcsecond[4] is the luminance of a moonless night sky dark enough to see the milky way properly. As natural as well as artificial hindrances like airglows and city lights interfere with the night sky, this value reduces, and structures in the night sky like the constellations and the milky way becomes faint and invisible. The light pollution map[5] is a global map that makes use of this ranging criteria called the Bortle scale to determine the brightness of locations across the globe.

there is — Earth at night. Credit: NASA/ Earth Observatory.

According to the map, most of New York City has a sky luminance of around 17-18 mag/square arcsec, which indicates intense light pollution, and only a few astronomical objects can be seen from the city. Magnitudes of luminance below 20, represent light-polluted skies, and most of the major cities in the world hold such skies. A 2013 article[6] on South China Morning Post, deemed the light pollution in Hong Kong, the 'worst on the planet'. Dots of light fill up the Eastern Coast of the U.S, Central Europe, India, and China in the Earth observatory image of our planet at night. While these lights are wondrous to gleam at from up above, it is estimated that a large percentage of the global population perceives dull skies.

So, What if there was a blackout?

Most people will see the sight of their lives. This is what happened in Los Angeles[7] during a blackout in 1994. Like New York, Los Angeles is also notoriously famous for its artificial sky glows, which is visible from afar. But during the power outage, the city went dark, and strange light clouds hovered above the residents. Some people even called emergency centers, for they had never seen a strange sky as that—but what they were truly gazing at, was in fact, the scenic beauty of our galaxy.

Places to see the night sky from

The light pollution map[8] and the darksite finder[9] are useful tools that enable an astrophile to find the perfect location to view the night sky from. It is always good to remember that the night sky is only as good as the darkness around you. Places with least human interaction, are places with low light pollution, and there are numerous such places across the world to see the real night sky from. Places like the Australian outback, the Sahara desert in Africa, the Siberian region in Russia, the northern part of Canada are mostly uninhabited and therefore possess spectacular night skies.

The perfect night sky does not show up under the veil of city night lights. But there could still be places nearby you that offer great nightscapes, and one could use a telescope most of the time. And if that doesn’t work out either, you could always hope for a blackout.

What does the night sky actually look like?

View from different hemispheres

Light pollution in cities

So, What if there was a blackout?

Places to see the night sky from

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