Chapter 5 of 10/4 min read
Planet or star?
How to recognise Venus, Jupiter, Mars and Saturn with the naked eye.
Star
Twinkles and flickers in colour, especially near the horizon.
Planet
Steadier light, found along the ecliptic.
To the naked eye planets look like stars, but there are reliable clues to tell them apart.
- Twinkling: stars twinkle a lot, planets shine with a steadier light because they are tiny discs rather than points.
- Position: planets are always found along the ecliptic.
- Motion: over days or weeks they shift against the stars ("planet" means "wanderer").
Planets visible to the naked eye
- Venus: the brightest point after the Sun and Moon, always near the Sun: you see it in the evening in the west or in the morning in the east.
- Jupiter: very bright and white, visible even in the middle of the night. Binoculars show up to four moons.
- Mars: orange-red; its brightness changes a lot with its distance from Earth.
- Saturn: yellowish, fainter; a small telescope shows the rings.
- Mercury: difficult, always low in twilight near the Sun.
The best dates to see them (oppositions and elongations) are in GAIA's calendar, computed for the next twelve months.