How far along Earth’s orbit does the Perseid cloud extend near the 2026 encounter?

Near Earth, the Perseid cloud is estimated to extend about 0.8 astronomical units along Earth’s orbit.

The Perseid stream is formed from material expelled by Comet Swift–Tuttle during many orbital passages. Once released, particles continue traveling around the Sun, and their positions become distributed over a large section of the comet’s orbit. The resulting cloud is therefore much longer than it is wide in the region crossed by Earth.

An astronomical unit, abbreviated AU, is the average Earth–Sun distance. A length of 0.8 AU is approximately 120 million kilometers. This does not mean that every point in that entire span produces identical meteor rates. Particle density varies, and some parts of the stream contain younger or denser filaments.

The elongated cloud explains why the 2026 Perseids are active across a broad interval of dates. Earth’s passage through different portions of the stream produces a gradual rise, a maximum near August 12, and a gradual decline afterward.