#comet r3

2026 April 12

Comet R3 (PanSTARRS) Brightens

A starry night is seen above foreground mountains. Toward the right is a comet with its head near the bottom center and a long tail extending toward the upper right.

Image Credit & Copyright: José Rodrigues

Explanation: Comet R3 is brightening rapidly -- will it survive? C/2025 R3 (PanSTARRS) has been slowly brightening and extending an ion tail since its discovery last year. This shedding mountain of dirty ice puts on its best sky show this month, though, because it passes its closest to both the Sun (April 19) and the Earth (April 25). The featured image, showing R3 already sporting a tail extending over 10 degrees, was taken two nights ago from Sion, Switzerland with the big mountain Bietschhorn on the left. Comet R3 will be visible during mid-April before sunrise. Although the future brightness of any comet is hard to predict, the brightness of R3 makes it already a good camera comet and it may become visible to the unaided eye in the next week. Comet R3's physical future is also unknown because, like Comet A1 (MAPS) earlier this month, it may disintegrate when it passes its closest to the Sun. Or it may live to leave the Solar System.

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)

NASA Official: Amber Straughn

A service of: ASD at NASA / GSFC,

NASA Science Activation

2026 April 14

The Long Wispy Tail of Comet R3 (PanSTARRS)

A star field surrounds a bright comet with a long tail. The green coma of the comet is seen on the lower left, while the light blue ion tail extends to the upper right and shows wavey structure.

Image Credit & Copyright: Haythem Hamdi

Explanation: Why does Comet R3 (PanSTARRS) have a wispy tail? The newest bright member of the inner Solar System, Comet C/2025 R3 (PanSTARRS) is already extending an impressive stream of glowing gas. This tail starts from an unseen central nucleus of dirty ice that is likely a few kilometers across. The nucleus is warmed by the Sun and emits a cloud of neutral gas into a coma that glows light green. Nuclear gas ionized by energetic sunlight is pushed away from the Sun by the solar wind into an ion tail that glows light blue. The wispy nature of the ion tail is caused by the constantly changing structure of the solar wind. Pictured from Rhode Island, USA two days ago, Comet R3 (PanSTARRS) shows off a many-degree ion tail. Comet R3 (PanSTARRS) is best seen before dawn from northern skies for another 10 days, after which it will be best visible from southern skies.

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)

NASA Official: Amber Straughn

A service of: ASD at NASA / GSFC,

NASA Science Activation