DoRevision Sign up free

Observing the Sun and Planets

Watch the Solar System from Earth: observe the Sun safely, follow the planets along the ecliptic, and learn the words for planet positions like opposition, transit and occultation.

⏱️ 17 min 🎯 14 activities Teachers Not yet rated Students Not yet rated

Revise this, the fun way

Play it interactively, earn XP and build a streak, free.

Start revising free

What you'll cover

Watching the Solar System 🔭

Topic 5 is about **observing the Solar System** from Earth: how the Sun and planets move across our sky, how to watch the Sun safely, and the words astronomers use for planet positions. Let us start with the key terms.

Key terms 📖

Learn these before you begin:

Match each term to its meaning

  • Ecliptic
  • Zodiacal Band
  • Retrograde motion
  • Radiant
  • The Sun's yearly path across the sky
  • The band of sky where the planets are seen
  • A planet appearing to move backwards
  • Where a meteor shower appears to come from

Observe the Sun safely ☀️

Never look directly at the Sun: it can permanently damage your eyes. To observe it safely, use **pinhole projection**: make a small hole in card and let the Sun shine through it onto a second card, forming a projected image you can look at safely.

Safe observation

What is the safe way to observe the Sun in the specification?

  • Pinhole projection onto a card
  • Looking through binoculars
  • Staring at it near sunset
  • Reflecting it into your eye with a mirror

Match each observation term to its meaning

  • Conjunction
  • Opposition
  • Transit
  • Occultation
  • A planet appears close to the Sun in the sky
  • A planet lies opposite the Sun, best for viewing
  • A planet passes across the Sun's face
  • One body passes in front of and hides another

Backwards planets and meteors 🔄

Usually planets drift slowly eastward against the stars. Sometimes an outer planet seems to stop and move westward for weeks: this is **retrograde motion**, caused by Earth overtaking it in orbit. **Meteors** are streaks of light from small particles burning up in the atmosphere. In a **meteor shower**, many appear to spread out from one point, the **radiant**.

Observing planets

Select the TWO true statements about observing planets.

  • At opposition, an outer planet is well placed for viewing all night
  • Retrograde motion is a planet appearing to move backwards for a time
  • A transit is when a planet hides a distant galaxy
  • The ecliptic is the path of the Moon only

Observation terms frame

When a planet lies opposite the Sun in our sky, it is at _____. When it passes across the Sun's face, that is a _____. The Sun's yearly path across the sky is the _____. A meteor shower seems to spread out from its _____.

opposition transit ecliptic radiant conjunction occultation equator horizon

At opposition

A planet is at opposition. Where is it compared with the Sun?

  • Opposite the Sun, so it rises as the Sun sets
  • Right next to the Sun, lost in its glare
  • Passing directly across the Sun's face
  • Below the horizon all night

Motion and meteors frame

A _____ is a streak of light from a particle burning up in the atmosphere. During _____ motion a planet appears to move backwards. The narrow band of sky holding the planets is the _____ Band. Two markers on the ecliptic are the First Points of Aries and _____.

meteor retrograde Zodiacal Libra comet direct Milky Gemini

Name the position

An interactive activity.

Apply what you know

An interactive activity.

Explain what you have learned

An interactive activity.