Longest lunar eclipse, blood moon, red planet on Friday

Amateur stargazers, who will stay awake late into Friday night, may be treated with a celestial spectacle comprising a blood moon, the century's longest lunar eclipse and a bright red planet in the sky.

Though India is one of the best sites in the world to watch the 103-minute long cosmic show in the intervening night of Friday-Saturday, monsoon clouds can play spoilsport.

“Tamil Nadu and Himalayan heights are the two best places to witness the cosmic show. In other places, people have to take a chance because of the monsoon clouds,” N M Ramanujam, astronomer and public outreach officer of the Astronomical Society of India, told DH.

A lunar eclipse takes place when the Moon enters the shadow of the Earth. On this night the Earth is directly between the Moon and the Sun, blocking the sunlight reaching the Moon, thereby casting its shadow on the Moon.

This time, people can witness a Blood Moon. A Blood Moon occurs when the moon moves to the core of the earth's shadow, the colour of the lunar disk turns red with many hues like crimson and brick red.

The reddish tinge comes from scattering and refraction of light as the blue wavelengths of the light are scattered by the Earth, making the Moon appear red. “At the beginning of the eclipse, the Moon will look reddish. As the eclipse progress, it will turn into a darker shade of the red,” Ramanujam said.

While the lunar eclipse is on, the Sun and Mars will be positioned opposite to each other with the Earth in the middle. Because of the Mars' opposition, Mars and Moon will appear in the same frame, six degrees apart.

“To a naked eye, Mars will appear brighter than other stars. With Red Moon and a bright mars it will be quite a site,” said Ramanujam.

The Moon will enter the penumbral (outer) shadow of the Earth at about 10:53 pm. Nothing much will be noticeable to the untrained eyes for the next 30 to 40 minutes. After that, one might notice a gradual change in the brightness on the lunar disk.

By 11:54 pm, the Moon will enter the umbra (core area) of the Earth's shadow. The dark shadow will now be seen progressing on the lunar disk. This will be quite noticeable to the naked eyes.

At 1:00 am on July 28, the Moon will be completely inside the umbra of the Earth, when it's colour will turn dark red. The time of the maximum eclipse is 1:51 am. The total phase of the eclipse will end at 2:43 am, it will be out of the umbral shadow by 3:49 am, and completely out of penumbra at 5:00 am.

Earth and Mars will be separated by just 57,590,017 km on July 31. This is the closest Mars has come to us since August 27, 2003.

Lunar eclipses don't have any effects on human beings and can be safely observed without any filters or telescopes from homes or terraces.

One should also note that it is perfectly safe to carry on your normal activities during the eclipse period, including eating and drinking, the public outreach and education committee of Astronomical Society of India said in a statement.