Best view of Mercury this year on Tuesday morning
Early risers will have one of the best chances of the year to spot Mercury in the pre-dawn sky on Tuesday.
The planet reaches what astronomers call greatest elongation west. This is the point where Mercury appears farthest from the Sun in the morning sky, making it visible shortly before sunrise. The planet will rise in the east and shine brightly against the early morning twilight.
Mercury is the fastest-orbiting planet in the solar system and from Earth’s perspective it never strays far from the Sun. As a result, it can only be seen for short periods just before dawn or just after sunset. When it appears in the evening sky the event is known as greatest elongation east, while its passage behind or in front of the Sun is called conjunction.
For the clearest view of Mercury on Tuesday morning, observers are advised to find an unobstructed horizon facing east and to begin looking about 45 minutes before sunrise. Binoculars may help if the sky is hazy or there is thin cloud.
The window of visibility is brief. Within days of elongation Mercury will sink back toward the Sun and disappear from view. Its next morning appearance will not take place until later in the year.
