Visitors

Be outside on the right night for a meteor shower, a comet, the ISS or the aurora.

7 guides · about 40 min

A line runs from a guide to the guides that build on it.

1. 1. Comets 6 min Why does a comet’s tail point away from the Sun?

   You’ll be able to say which way a comet’s tails will point, and why.

   Begin
2. 2. Meteor Showers 6 min Why will you see fewer meteors than the forecast promises?

   You’ll be able to find a shower’s radiant and set out to watch it at the right hour.

   Leads to

   Shooting Stars Aren’t Stars

   Begin
3. 3. Shooting Stars Aren’t Stars 5 min What is a shooting star, if it is not a star?

   You’ll be able to tell a meteor from a star, say what burns up in one and how high, and name the comet behind a shower.

   Builds on

   • Meteor Showers. It uses “radiant”, which Meteor Showers explains.

   Begin
4. 4. Satellites and the ISS 6 min What is the steady light gliding across the sky at dusk?

   You’ll be able to tell a satellite from a plane or a meteor, and find tonight’s ISS pass.

   Builds on

   • Understanding Star Brightness · Observing Skills. It uses “magnitude”, which Understanding Star Brightness explains.

   Leads to

   Satellite Orbits

   Begin
5. 5. Satellite Orbits 6 min Why is the ISS round again in 90 minutes, while a TV dish never moves?

   You’ll be able to say why the ISS is round again in an hour and a half, and point to the geostationary belt.

   Builds on

   • Satellites and the ISS. It starts from the steady light you learned to spot in Satellites and the ISS.

   Begin
6. 6. A Visitor from Another Star 6 min How do we know 3I/ATLAS came from another star?

   You’ll be able to tell an interstellar visitor from a comet that belongs to the Sun.

   Builds on

   • Understanding Star Brightness · Observing Skills. It uses “magnitude”, which Understanding Star Brightness explains.
   • Racing and Crawling · Planets. Its proof is a speed too fast for the Sun to hold, from Racing and Crawling.

   Begin
7. 7. Aurora 6 min Where do you go to see the northern lights, and when do they come south?

   You’ll be able to say where on Earth the northern lights are overhead, and read a Kp forecast for how far south they will reach.

   Begin

From other paths

Guides on this path build on these.

• Understanding Star Brightness · Observing Skills · 10 min It uses “magnitude”, which Understanding Star Brightness explains.
• Racing and Crawling · Planets · 4 min Its proof is a speed too fast for the Sun to hold, from Racing and Crawling.