After the disappointing breakup of Comet ATLAS – for a short period thought to be the best comet we’d see in years – dashed our sky spectacle dreams, Comet SWAN popped up and gave us new hope. Pretty soon it became visible to the naked eye, and from now until mid-June it’s at its best, so take a step outside and look up.
May was the month Comet C/2019 Y4 (ATLAS) was supposed to be an unusually bright spectacle in the sky, but alas, its close approach to the Sun led instead to the spectacular fracturing of its nucleus and its ultimate disintegration – although still captured in stunning images by Hubble.
Comet C/2020 F8 (SWAN) was discovered in late March, but only really piqued astronomers’ interests as our hopes of being able to see ATLAS with the naked eye were being dashed. After its magnitude (brightness) jumped 100-fold in just a few days, suggesting it would become visible in May, images of what looked like ATLAS’ disintegration in April showed it getting fainter.
SWAN, on the other hand, has fulfilled its promise, hitting a magnitude of 5.6 on May 2, meaning it officially became visible in the night sky to the naked eye, without the need for special equipment – though you will need dark skies to see it, and binoculars or a telescope never hurt.
After making its closest pass to Earth at around 84 million kilometers (52 million miles) on May 12, SWAN is currently about 110 million kilometers (68 million miles) from Earth and a magnitude of 6.1. It should be at its brightest as it gets closest to the Sun on May 27, potentially peaking at a magnitude of 3, though it's now thought that is optimistic as it has stopped brightening in the last few days.
There is of course a chance that the comet will disintegrate as it approaches the Sun, just like ATLAS. Comets are often described as “dirty snowballs”, small icy bodies made up of frozen gases, rock, and dust, that orbit the Sun. When a comet's orbit takes it close to the Sun, the heat melts the ice and the comet's nucleus fragments, spewing out gas and dust, creating a gaseous tail as the comet continues on its journey.
So, how and where can you spot SWAN?
The green-tinged comet has been visible in the Southern Hemisphere for a while, but now it's visible in the Northern Hemisphere too, though bright twilight and its position low on the horizon may make viewing it tricky. Your best chance is to find dark skies away from artificial light, and, using binoculars, look to the north-west after sunset or the north-east an hour before sunrise, about 10 degrees above the horizon (hold your clenched fist out in front of you, that's about 10 degrees). If you have a stargazing app on your phone, or just know your constellations, SWAN is currently located near the Perseus constellation.
It is worth pointing out the spectacular images you may have seen of SWAN are most likely taken with long exposures and that is not what you will actually see if you look up (this is a harsh truth for northern lights-seekers too, beware). However, for those of us who have been under lockdown for months, it's good to occasionally step outside, look up, and perhaps gain a new perspective.