At a glance
- Found in
- Astronomy & Skywatching
- Related
- Superior Conjunction, Planetary Transit, Transit of Venus, Lunar Libration
It is a rare Mercury-Sun-Earth alignment near an orbital node.
A scientific orientation to scale, light, or motion; the article supplies the precise definition.
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The story behind Transit of Mercury
Astronomers timed Mercury transits for ephemeris tests and solar-system measurements.
A one-minute story
The Wandering Stars
How the moving planets were watched, named and found, and what a transit is.
Why Transit of Mercury matters
Transit of Mercury demonstrates inner-planet geometry and permits precise timing observations.
Transit of Mercury in practice: an example
Mercury appears as a tiny black disk moving gradually across the filtered solar image.
Where readings of Transit of Mercury go wrong
Eclipse glasses alone do not magnify Mercury, and unfiltered optical viewing can cause instant eye injury.
Sources and editorial method
Research references used for this entry include:
- NASA Science: What’s a Transit? - NASA explanation of planetary transits, light curves, and what transit measurements reveal.
- NASA Science: Eclipse Viewing Safety - Official solar-viewing guidance for eyes, cameras, binoculars, and telescopes.
- Source
- The Great Almanac Dictionary
- Category
- Astronomy & Skywatching
- Last updated
- 2026-09-26
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More in Astronomy & Skywatching
- Apogee
- Binocular Astronomy
- Ecliptic Coordinate System
- Heliosphere
- Main Sequence
- Perigee
- Red Giant
- Solar Granulation
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Common questions
What is a Transit of Mercury?
A Transit of Mercury is the passage of Mercury’s dark silhouette across the Sun as viewed from Earth.
What do people get wrong about a Transit of Mercury?
Eclipse glasses alone do not magnify Mercury, and unfiltered optical viewing can cause instant eye injury.
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