Newly-discovered Comet SWAN is now visible to the naked eye after making its closest pass to the Earth
A recently-discovered comet made its closest pass to the Earth on May 13, at a distance of about 53 million miles, a little more than half the distance from Earth to the Sun. Comet SWAN is now visible to the naked eye, and it may get brighter, say scientists.
Comet SWAN's initial discovery was made via an instrument onboard the European Space Agency (ESA) and National Aeronautics and Space Administration or NASA’s Solar and Heliospheric Observatory (SOHO) satellite. The new comet was first spotted in April this year by an amateur astronomer named Michael Mattiazzo using data from a SOHO instrument called Solar Wind Anisotropies, or SWAN. The comet -- officially called C/2020 F8 (SWAN) but nicknamed Comet SWAN -- was spotted in the images because it was releasing huge amounts of water, about 1.3 tons per second. As water is made of hydrogen and oxygen, this release made Comet SWAN visible to SOHO's instruments.
According to a May 13 NASA article, in late May and early June, “earthlings may be able to glimpse Comet SWAN.” The comet is “currently faintly visible to the unaided eye in the Southern Hemisphere just before sunrise, providing skywatchers with a relatively rare glimpse of a comet bright enough to be seen without a telescope,” said the article.
Comet SWAN's closest approach to the Sun, called perihelion, will happen on May 27. Though it can be very difficult to predict the behavior of comets that make such close approaches to the Sun, scientists are hopeful that SWAN will remain bright enough to be seen as it continues its journey. As comets get closer to the Sun, and the temperature gets hotter, they tend to heat up and start shedding material in a dust trail that can be visible in images. The ice, dust, and rock that makes up a comet can then break up or become more visible, and it is difficult to know how any given object will behave in the circumstances.
Comet SWAN is currently in the constellation of Triangulum. “I am VISIBLE to the naked eye! I am 88,960,206 km away from Earth and my current magnitude is 5.6. You can spot me near the Triangulum constellation,” says a May 16 Twitter post on the comet. The account is regularly updating SWAN’s position. According to astronomer Con Stoitsis, some predictions show the comet will continue to brighten in the coming days. “Recent light curve predictions for Comet C/2020 F8 Swan indicating a maximum magnitude of approx +3.5!. It should be an “obvious” naked eye target in mid-May,” he tweeted on April 30.
However, Comet SWAN has not become as bright as anticipated though. “On April 24, the comet was shining at magnitude +7.2, which is too faint to be seen with the naked eye and only accessible with binoculars or telescopes. Magnitude is a measure of the brightness of a star or other celestial body. The brighter the object, the lower the number assigned as a magnitude. The brightest stars are magnitude 0 or +1; the faintest stars visible without optical aid are +6,” reports Space. The article further says, “Less than a week later, on April 30, the comet's brightness had surged more than six-fold, reaching magnitude +5.2. By that time, the comet was faintly visible in a dark sky with the unaided eye. But ever since then, the comet's brightening has stalled and even has appeared to dim a little, hovering at around magnitude +5.6.”
Comet SWAN is the 3,932nd comet discovered using data from SOHO. Almost all of the nearly 4,000 discoveries have been made using data from SOHO's coronagraph, an instrument that blocks out the Sun's bright face using a metal disk to reveal the comparatively faint outer atmosphere, the corona. This is only the twelfth comet discovered with the SWAN instrument since SOHO's launch in 1995, eight of which were also discovered by Mattiazzo.