700-metre ‘twilight’ asteroid found inside Venus’s orbit, circles Sun in just 128 days

Astronomers have identified a rare asteroid racing unusually close to the Sun. Designated 2025 SC79, the asteroid orbits the Sun every 128 days, making it the second-fastest known asteroid and only the second ever found inside Venus’s orbit.

Who discovered 2025 SC79 and where?
Scott S. Sheppard of the Carnegie Institution for Science first observed the asteroid on September 27, 2025. He used the Dark Energy Camera at the Blanco 4-meter telescope in Chile. Follow-up observations were conducted with the Gemini and Magellan telescopes to confirm its existence.

The asteroid is estimated to measure about 700 meters in diameter. Its orbit crosses Mercury’s path, and it remains largely hidden from Earth’s view in the Sun’s glare. Sheppard described such “twilight” asteroids as challenging to detect because they appear only at dawn or dusk.

Why are ‘twilight’ asteroids significant?
Sheppard explained that the most dangerous asteroids are the hardest to spot. “Most asteroid research finds objects in the dark of night,” he said. “Asteroids near the Sun can approach Earth and remain unnoticed, posing serious impact risks.”