March 12
The Brand on the Camel
Sun Position
The Sun is in Pisces at roughly +13° declination, with the Northern Hemisphere now clearly in the long-day side of the year and the Southern Hemisphere heading toward the autumn equinox within days.
Sky Highlight
Gemini is still well-placed in the west in mid-March evenings, but it is now clearly past its highest point and sinking toward the spring horizon. The next few weeks offer the last comfortable evening views of Castor, Pollux, and Alhena before they descend into twilight for northern observers.
Deep Sky Object
M1 (Crab Nebula), a supernova remnant in Taurus, about 6,500 light-years away, expanding at roughly 1,500 km/s from the stellar explosion of 1054 CE; it remains one of the most studied objects in the sky, now sinking into the west in spring evenings. Visible from both hemispheres at low altitude in March.
Featured Star
Alhena (γ Gem) is a white subgiant 109 light-years away with spectral class A0IV, sitting at the foot of the Gemini twins and notable as a spectroscopic binary. Its Arabic name derives from a word meaning a brand or mark placed on a camel's neck, one of many star names that preserve the livestock and caravan imagery of medieval Islamic astronomy.
Around This Date
- March 13, 1610Galileo published Sidereus Nuncius (Starry Messenger), the first scientific work based on telescopic observations, reporting his discovery of Jupiter's four large moons and the mountains of the Moon, observations that directly challenged Aristotelian cosmology.
- March 13, 1781William Herschel discovered Uranus on this date, initially believing it to be a comet; it was the first planet found with a telescope and the first planet discovered in recorded history.
A camel-brand encoded in starlight: Alhena carries its name across 109 light-years of silence.