Comet Neowise In Havre de Grace: PHOTOS

HAVRE DE GRACE, MD — Neowise is the brightest comet in nearly a quarter of a century, and it came closest to the Earth Wednesday night. For the past couple of weeks, it has been visible, including near Havre de Grace.

Measuring about 3 miles in diameter, it is large by comet standards, according to NASA, which found it earlier this year.

The comet gets its name from the mission that discovered it in March. NASA's Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) detected the comet — which is a frozen mass of rock, gas and ice left over from when the solar system formed — using infrared channels that pick up heat signatures.

"From its infrared signature, we can tell that it is about 5 kilometers [3 miles] across, and by combining the infrared data with visible-light images, we can tell that the comet's nucleus is covered with sooty, dark particles left over from its formation near the birth of our solar system 4.6 billion years ago," said Joseph Masiero, NEOWISE deputy principal investigator at NASA's Jet Propulsion Laboratory in Southern California.

Since June 9, the comet has brightened 100-fold. It appears to rise tail first, followed by its bright head or coma, which Space.com said shines "as bright as a first-magnitude star" — a designation reserved for the brightest of stars. For comparison, the North Star is a second-magnitude star.

After making its closest approach to Earth between July 22 and July 23, Neowise will fade until it eventually disappears from the solar system.

The comet is the brightest to visit Earth since Hale-Bopp in 1997.

— By Beth Dalbey and Elizabeth Janney