January 20
The River's Bend
Sun Position
The Sun lies in Aquarius, about 20.4° south of the celestial equator. In the Northern Hemisphere the days are still short but lengthening; in the Southern Hemisphere this is high summer with long, warm evenings.
Sky Highlight
The Sun crosses into Aquarius today by the tropical zodiac. Eridanus, the celestial river, winds southward from Orion toward the horizon. Its far end is best seen from the Southern Hemisphere.
Deep Sky Object
The Tarantula Nebula (NGC 2070) in the Large Magellanic Cloud, a star-forming region so luminous it would cast shadows if it sat as close as the Orion Nebula. Southern Hemisphere only.
Featured Star
Acamar (θ Eri), a white giant / white main-sequence pair in Eridanus, about 161 light-years away. Acamar, the former end of the river, displaced when the deeper south was mapped.
Around This Date
- January 20, 1930Clyde Tombaugh began the systematic photographic plate comparison at Lowell Observatory that would lead to his discovery of Pluto eighteen days later, the last planet found without prior prediction from orbital data.
- January 24, 1986Voyager 2 made its closest approach to Uranus, the only spacecraft to ever visit the planet, discovering ten new moons, two new rings, and a magnetic field tilted nearly 60° from the planet's rotation axis.
A river of stars pours off the edge of the visible sky.