Distant observatories compare transit timings

Richard Hodgson independently observed the unusual white-light flare.

The 1 September observations are among the first recorded sightings of a solar flare.

A powerful geomagnetic storm followed; the sequence later helped develop the study of space weather.

The UTC catalog fixes the transit on 9 December, giving astronomers another rare timing opportunity.

Observing campaigns used cameras as well as telescopes to document Venus crossing the Sun.

The 1874 event drew coordinated work across multiple countries and hemispheres.

Hall spotted the first of Mars's two known moons; the recorded date is 11 August in US local time.

Finding Deimos overturned the assumption that Mars had no detectable satellites.

Accounts of the discovery describe Angelina Hall urging her husband to continue looking for Martian moons.

Repeated observing established that the object was associated with Mars.