What Is a Penumbral Lunar Eclipse and What Does It Look Like?

Large swathes of the globe have just witnessed what's known as a penumbral lunar eclipse as a full moon appeared in the night sky.

There are three main types of lunar eclipse—total, partial and penumbral—all of which only occur when the moon is full. At these moments, our planet is positioned directly between the sun and the moon in space.

Unlike total and partial lunar eclipses, penumbral lunar eclipses are relatively subtle affairs, sometimes to the point of being imperceptible.

Penumbral lunar eclipse when the outer, more diffuse part of the Earth's shadow—known as the "penumbra"—falls onto the face of the moon that we can see.

During these events, some or all of the moon appears slightly darker than usual for a period of several hours as the penumbra passes over our planet's natural satellite.

Penumbral eclipses can be either full or partial. During a full penumbral eclipse, the Earth's penumbra covers the entire face of the moon—by the point of peak eclipse—turning it a shade darker.

During partial penumbral eclipses, only part of the moon's surface is covered by the penumbra, which can very difficult—or even impossible—to see.

Lunar eclipses are visible across the entire part of the Earth that is experiencing night time when the event is occurring. This differs to solar eclipses, which can only be seen across a very narrow path from a (relatively) small region of our planet.

All lunar eclipses occur when the Earth passes between the sun and the moon, casting a shadow on our natural satellite.

Unlike during a total lunar eclipse when the sun, Earth and moon are in almost perfect alignment, penumbral eclipses occur when the three bodies are only imperfectly aligned during the full moon phase.

At these times, the Earth only blocks some of the suns light from directly falling on the moon's surface.

"A penumbral lunar eclipse happens when our moon is 'kissed' only marginally by the most external regions of the structure of the Earth's shadow," astronomer Gianluca Masi, from the Virtual Telescope Project, previously told Newsweek.

The penumbral eclipse that took place on November 30 was visible across most of the Americas, northeastern Asia, much of the Pacific Ocean, large swathes of the Atlantic, and the Arctic, according to timeanddate.com

The eclipse began at 02:32 a.m. ET on November 30 and ended four hours and 21 minutes later. Maximum eclipse took place at 09:42 a.m. ET when around 82 percent of the moon was covered in the Earth's penumbra.

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A full moon is seen from Chennai, India, during the penumbral lunar eclipse on June 6, 2020. ARUN SANKAR/AFP via Getty Images