Spring Sky Watch: Newly discovered comet on the horizon
A new interstellar visitor was discovered in late March: a previously unknown comet designated C/2025 F2 (SWAN). An amateur astronomer in Australia, Michael Mattiazzo, discovered the comet by studying images taken from the Solar and Heliospheric Observatory 9, a joint venture from NASA and the European Space Agency that launched in 1995.
The comet is currently visible with binoculars on the east-northeast horizon at dawn. As it approaches and — hopefully — passes the sun, it should grow brighter.
Comets are mostly made up of ice, dust and rocky debris. As they approach the sun and heat up, part of the outer layer melts away, creating a temporary atmosphere called a coma. The newest comet’s coma contains reactive molecules called diatomic carbon (C2), which give it a greenish glow when illuminated by sunlight, according to earthsky.org.
If C/2025 F2 (SWAN) stays intact during its trip toward the center of our solar system, it should be visible to the naked eye in the first days of May. To see the comet then, choose a wide, open area and look toward to the northwest horizon around dusk.
Alan Cousins from the Custer Institute and Observatory in Southold does not expect the new comet to be observable from Custer’s telescope. “When it might be visible in the sky, it’s going to be rather low. We can only sight down so far,” he said. “It might be right at a threshold of our ability to look that low on the horizon.”
The comet was temporarily named SWAN25F, but has been officially renamed to C/2025 F2 (SWAN) after the discovery was confirmed by the International Astronomical Union’s Minor Planet Center.
In other astronomical news, the full moon on April 12 was the smallest apparent view of the year. That’s because it’s considered a micro moon — the opposite of the better known super moon phenomenon. Since the moon’s orbit is not a perfect circle, there is variation in how close it is relative to Earth, affecting how big it looks in our skies.
“You’ve heard of instances where it’s a super moon because the moon is closest to us, right? So it appears larger,” Mr. Cousins said. “Saturday, [April 12,] the full moon is at the furthest distance from us, because the moon goes around [the earth] in an elliptical orbit.”
Towards the end of April and beginning of May, there are two meteor showers to watch for. First up is the Lyrids, which runs from April 16 through 25. This shower can produce up to 20 meteors per hour at its peak on the night of April 21. The moon will be at 40% full, which could impact visibility. The Eta Aquarids, peaking on May 5, are not as strong in the Northern hemisphere, with rates of 10-30 per hour just before dawn. The first quarter moon sets just before the shower begins.
