When the Red Moon and the Red Planet turn brightest and biggest

The day July 27, 2018 will go down in history with a great and rare celestial moment. It will witness the blood moon in the longest total lunar eclipse of the 21st century. And there's more to take place. Space enthusiasts are preparing for the long-awaited phenomenon of not only the longest total lunar eclipse (Chandra Graham 2018) but also Mars opposition during the same time.

As the moon passes the earth’s shadow on July 27, at 10:37 pm IST, Mars, Earth and the Sun will be spinning along a straight line. And the Red planet will be seen besides the red (eclipsed) Moon in the night, astronomers say.

Mars would rise around the sunset time and will set around the time of sunrise. An opposition happens when Mars is the closest to Earth in its orbit, both on the same side of the Sun. 

The Red Planet, as it comes closest to the earth on 31 July, will appear brighter and bigger than usual.

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On this day, the brightest star in the night sky, Sirius will be about three times fainter than Mars and the average angular size of the moon is 1800. 

The opposition of Mars is on July 27, but it approaches closest to the earth on 31 July. This curious fact is because the orbits of all planets around the Sunare not a perfect circle, but an ellipse. Because of it, Mars will come closest to the earth four days later than its opposition. This is one of the reasons the distance between Mars and Earth is not the same during every opposition.

This July, Mars comes the closest to Earth as compared to any other time in the last 15 years. Hence, it will appear to be the biggest and brightest in the last 15 years. During the phenomenon, Mars will be just 58 million kilometres from the Earth. 

The angular diameter of Mars as seen from the Earth will be more than 24" and it will be brighter than -2.75 magnitude.

Read More | Chandra Grahan 2018: India witnesses Blue Moon, is your zodiac sign affected by the lunar phenomenon? 

Mars would appear small even at the closest approach. It would need a telescope equipped with a lens or mirror that is at least 6 inches in aperture to discern even the major surface features of the planet.

The distance between Mars and the Earth ranges between about 400 million kilometres (2.7 Astronomical Units, or AU) and 56 million km (0.38AU). The closest approaches occur during oppositions.

(With PTI inputs)