Are urban night skies suddenly cleaner and clearer?
Does the coronavirus lockdown mean best-ever views for stargazers? There was a report last weekend in The Times about how stargazers in the U.K. can now see Venus because of the decline in pollution. It’s really misleading. Venus is the third-brightest object in the night sky, after the sun and the moon, and has been easy to see in any clear sky in the world for months. The current lack of pollution makes zero difference to seeing Venus, and any of the planets; stargazers have been looking at Venus—presently a whopping 41º above the western horizon after sunset—with ease since before Christmas.
However, when it comes to star-gazing, it’s possible that the coronavirus lockdown and the resulting lessening of pollution—particularly light pollution—may make backyard stargazing easier. As an example, imagery from the European Space Agency’s Sentinel-5P satellite shows that since mid-February levels of nitrogen dioxide (NO2) have drastically reduced compared to the same six-week period in 2019.
These images, using data from the Copernicus Sentinel-5P satellite, show the average nitrogen ... [+]
So is the reduced economic activity actually making the sky more transparent for stargazers? “Certainly the absence of planes is great for astrophotographers, although satellite pollution is on the rise at the very same moment,” says Tom Kerss, an astronomy and science communicator who hosts the weekly Star Signs: Go Stargazing! podcast. He’s referring, of course, to SpaceX Starlink satellites. “It would be curious to see the results from a light monitor of taking some vehicles off the road since – car headlights are a contributor to light pollution, after all. And air pollution does influence observations of very faint objects, too.”
However, let’s not overstate things. Cities are still lit-up. “The effects are probably extremely negligible in a city like London, which is still rather active,” says Kerss, though he does cite one big difference since the cessation of sports fixtures. “Football stadiums with floodlights are usually cursed by stargazers who live near them,” he says. “Patrick Moore use to speak of the ‘Aurora Bognis,’ and I can say from experience of observing from his garden in Selsey that they were worse when Bognor Regis Town FC put their stadium lights on!”
It’s debatable, and hard to prove any deviance for it, but one thing is for sure—backyard stargazing is now a growing hobby.
So how do you do it? Here are Kerss’ top five tips:
Top 5 tips for urban stargazers
1 – Set your expectations for the city sky
We lose many faint stars to light pollution, but in some ways this can make familiarising yourself with the constellations a little easier. If you have a star chart, the brightness of a given star is shown by its size—bigger blobs are brighter stars. In light polluted skies, only the brighter stars are visible so memorise the locations of the bigger dots in each constellation.
2 – Find a good, safe stargazing spot nearby.
Of course, no urban site is ideal, but to make the most of your skies, you need to first make the most of your eyes. In order to become properly adapted to the dark (or as near as you'll get in the city) you should find a spot without direct light sources—such as streetlights or car headlights—shining into your eyes. After 20-40 minutes, you'll be as dark-adapted as the sky will allow, and you may be surprised by the number of fainter stars that become visible. Take care not to spoil your low-light vision by glancing at a screen or other light source.
Despite the lockdown, cities are still heavily light-polluted.
3 – Keep one eye on the news
Know about bright events that you can see no matter the quality of your sky. The Moon and naked-eye planets are always bright enough to be found, and they frequently buddy up in beautiful conjunctions. There are also bright meteor showers that take place on an annual basis. The Perseids in August and Geminids in December are particularly celebrated as they produce good numbers of shooting stars, the brightest of which are easily seen through light-pollution. Meteor-watching can be really thrilling! The International Space Station, which regularly outshines the planets, is also visible sailing overhead when the timing is just right. Go out and wave to the astronauts!
4 – Use binoculars
If you own a pair of binoculars, they're a great tool for taking your next step in stargazing. You can also find very inexpensive binoculars in shops or online. Binoculars show us many times more stars than we see with our eyes by gathering more light, and since they zoom in, the contrast we see in the image is enhanced. As a result, there are many “deep sky objects” like star clusters, nebulae and even galaxies that can be found from your urban observing site. My distance record for deep space exploration with binoculars in London is about 100 million light-years—can you beat it?
5 – Don't let light pollution get you down
More than half of us all over the world live in towns and cities, with very limited access to the sky, but that doesn't mean we can't be stargazers. The practise you get stargazing at home, wherever you live, will pay dividends when you're standing under a dazzling dome of stars in a perfect stargazing spot. Enjoy the urban sky for now, and make plans for your next trip!
Trips to “dark sky destinations” might be on hold for now, but we can all go stargazing from our backyards, balconies and even through windows. “I'm doing my best to emphasise that at this time, stargazing, moon watching, even searching for a comet can be a source of solace and connection to the natural world at a time when we feel cooped up and isolated,” says Kerss. “It’s a sight we all share after all, and the Universe is ancient enough to remind us that this too shall pass.”
Wishing you clear skies and wide eyes.
