Rain and cloudy skies could prevent sky gazers from watching Friday’s lunar eclipse in Delhi, the city’s Nehru Planetarium has said. The planetarium has organised a “Moon Carnival” for people in the national capital to watch the eclipse, PTI reported.

The eclipse will be the longest in the 21st Century, starting at 10.44 pm and ending over six hours later, at 4.58 am on Saturday.

The Nehru Planetarium has arranged as many as five telescopes and has organised lectures. Amateur astronomers will guide people about the eclipse. “But all this is subject to the rains and cloudy sky,” the planetarium’s Director N Ratnashree said. “There is already a lot of enthusiasm among people.”

The moon will enter the penumbral shadow of the Earth between 10.44 pm and 10.53 pm, and will be followed by a partial eclipse from 11.54 pm. This phase will proceed into a total eclipse by 1 am on Saturday, which will stay till 2.43 am. The subsequent partial eclipse will end at 3.49 am, and the moon will move out of the Earth’s penumbral shadow by 4.58 am on Saturday.

The lunar eclipse will coincide with the closest approach of Mars to Earth, PTI reported. “For serious astronomers, this event does offer an extraordinary opportunity to study Mars through their telescopes,” the Astronomical Society of India said, according to the agency. “However, a layperson who might expect to see dramatic details of the surface of Mars would probably be disappointed.”

Aniket Sule, chairperson of the Astronomical Society of India’s Public Outreach and Education Committee, said people in Jammu and Kashmir and Tamil Nadu will be able to watch the eclipse clearly.