Phaethon’s journey at perihelion

A two-hour sequence of the asteroid Phaethon from the perspective of ESA’s SOHO observatory. The images were taken on 15 May 2022 when the asteroid’s orbit ventured close to the Sun, at a distance of 21 million km. The orange filter on the coronagraph LASCO was used to image this asteroid, which is circled in the animation.

While SOHO routinely observes the Sun, it also observes many Sun-skirting objects including meteors and asteroids.

The 5.8 km-wide asteroid Phaethon is thought to be the parent of the Geminid meteor shower. As it passes close to the Sun, the orange filter observes a bright cloud surrounding the asteroid. While no tail is readily visible here, stacking the images together reveals its presence. The random specks of white are energetic particles, or cosmic rays, that constantly bombard the SOHO camera.

The brightness of the asteroid was originally attributed to the release of dust particles, however these images in the orange filter suggest that the emission of sodium atoms causes this activity. These observations, combined with those from the NASA STEREO mission, open up new possibilities about the formation of the Geminid meteor shower.

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