Meteor shower: Halley's dust trail and the Earth
About this app
Halley's comet on its real orbit, about 76 years, out beyond Neptune. Near the Sun it loses dust that spreads along the whole orbit. Earth crosses this trail twice a year: in early May (Eta Aquariids) and around 21 October (Orionids).
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
The science
A meteor shower happens when Earth flies through the dust trail of a comet. Halley's comet goes round the Sun in about 76 years on a long ellipse: closest to the Sun 0.6 AU (February 1986), farthest out about 35 AU beyond Neptune's orbit (end of 2023). Near the Sun, ice evaporates and carries dust away. The grains stay almost on the comet's orbit and spread along the whole orbit over many revolutions. Earth comes close to this orbit twice a year: in early May (Eta Aquariids) and around 21 October (Orionids).
What you see
The scene shows the Sun, planetary orbits and Halley's orbit with its real orbital elements, tilted from the side or from above. A year slider moves the comet from 1986 to 2062; near the Sun it grows a tail. In the dust trail scenario a cloud of dust spreads from the comet along the whole orbit. The close-up shows Earth's orbit with two crossing points; a date slider moves Earth through them, and while it is in the dust, meteors flash around it. In the overview the distances are compressed so that Earth and Neptune fit in the same picture.
Things to try
Set the year to 2026: the comet is far out, and yet Earth flies through its dust in October. Drag the date across 6 May and 21 October and compare the hourly rates. Rotate the view to see that Halley's orbit is only slightly tilted against Earth's orbit, but runs backwards.
Frequently asked questions
- Where do the Orionids come from?
- The Orionids are dust grains from Halley's comet. It lost them on earlier passes by the Sun, and they lie along its orbit. Around 21 October Earth flies through this dust trail, and every grain that hits the atmosphere lights up as a meteor.
- Why do meteor showers happen at the same time every year?
- A comet's dust trail stays almost fixed in space, and Earth is at the same place on its orbit on every date. So it reaches the trail on the same day every year. Whether the comet itself is nearby hardly matters.
- When will Halley's comet return?
- Halley was closest to the Sun in February 1986. At the end of 2023 it reached its farthest point beyond Neptune's orbit and has been falling back since. On 28 July 2061 it will be near the Sun again and visible in the sky.
- What does the "meteor shower" app show?
- Halley's orbit with real orbital elements, the dust along the orbit and Earth crossing the dust trail in May and October. Year, date and viewing angle can be set freely.
Subject: Astronomy
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