Mercury Hits Greatest Elongation: How to See It Tuesday
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- Mercury reached its greatest western elongation on Sunday, appearing at its greatest apparent distance from the sun in the morning sky — one of the best viewing opportunities of the year.
- Mercury, trapped in a small orbit around the sun, never strays far enough to escape dawn or dusk light, making elongations like this the rare chance to catch it.
- From London, Mercury will appear about a handspan above the east-north-east horizon between 04:30 and 05:00 BST on Tuesday, with the planet steadily brightening to improve contrast against the gathering dawn.
- Sunrise from London occurs at 05:28 BST on Tuesday, so observers must stop using binoculars well before that time to avoid eye damage while scanning for Mercury.
- Mars offers a bonus target during the same pre-dawn window, sitting higher and further east than Mercury and easier to spot.
- An unobstructed line of sight towards the east-north-east is essential, the chart shows, because any buildings or terrain will swallow the planet before it clears the horizon.
Why it matters: Mercury sightings require precise timing — most skywatchers go years without seeing it — and the roughly 30-minute window between Mercury's appearance above the horizon and sunrise at 05:28 BST on Tuesday is the narrow, concrete opportunity to catch it this elongation cycle.
