May 29
The Preceding One
Sun Position
The Sun is in Gemini at roughly +21.6° declination. The Northern Hemisphere is near its longest days of the year. In the southern mid-latitudes, winter settles in: cold, clear nights and early darkness.
Sky Highlight
On May 29, 1919, Arthur Eddington and Frank Dyson confirmed the deflection of starlight by the Sun's gravity during a solar eclipse, providing the first experimental proof of general relativity. That result transformed cosmology and opened the modern era of gravitational astrophysics. The centenary of that observation passed in 2019.
Deep Sky Object
M10 (NGC 6254), globular cluster in Ophiuchus, about 14,300 light-years away. A bright, well-resolved globular that rewards even a small telescope. It sits near M12 in the same constellation, the two making a classic binocular pair that observers can sweep between in a single field shift. Rising well for southern and equatorial observers in late May evenings.
Featured Star
Sabik (η Ophiuchi) is a white main-sequence pair 88 light-years away, spectral class A2V + A3V. The two components orbit each other in about 88 years. Its name comes from an Arabic phrase meaning 'the preceding one,' describing its position relative to other stars in the serpent-bearer. It lies in a rich field near the center of the galaxy.
Around This Date
- May 29, 1919Eddington's eclipse expedition measured the deflection of starlight passing near the Sun, confirming Einstein's prediction from general relativity and making headlines around the world.
- May 30, 1966Surveyor 1 made the first successful soft landing on the Moon by an American spacecraft, touching down in Oceanus Procellarum and transmitting more than 11,000 photographs of the surface.
Gravity bends light; a moment in 1919 proved what a century of mathematics had said.