Planet Mars near the Earth

Lunar Eclipse Today the longest one this century

Lunar Eclipses will occur during the night of 27th July 2018 to early hours of 28th July 2018

The next time we will see a similarly long eclipse will be on June 25/26, 2029 total lunar eclipse




The plane in which the Earth moves around the Sun is known as ecliptic plane. The Moon moves in a smaller orbit around the Earth. The plane of the Moon’s orbit is not aligned with the ecliptic plane, but it is inclined to the ecliptic plane by about 5 degrees. Because of this, only very rarely, the moon crosses the imaginary line connecting the Sun and the Earth. Whenever this happens, an eclipse of the Sun takes place.

Had this plane of the Moon aligned with the ecliptic plane, every new moon day an eclipse of the Sun would have occurred and every full moon day an eclipse of the Moon would have occurred. When the Moon moves in the shadow of the Earth, it is known as the eclipse of the Moon or lunar eclipse. Lunar eclipses can take place only during full-moon days, when the Moon comes diametrically opposite to the position of the Sun, as viewed from the Earth. Only very rarely, the moon reaches the imaginary line connecting the Sun and the Earth and crosses the Earth’s shadow in space. During other full moon days the Moon will pass above or below the Earth’s shadow, hence no eclipse results.

The shadow of the Earth cast by the Sunlight will have two components. One is darker shadow or umbra and the other is lighter shadow or penumbra. When the entire disk of the Moon crosses the darker shadow, the eclipse is known as total lunar eclipse. One such eclipse of the Moon will occur during the night of 27th July 2018 to early hours of 28th July 2018. The Total Lunar Eclipse of 2018 July 27-28 is visible from the following geographic regions: South America. Europe, Africa, Asia, Australia The partial phase begins at 23:54 hrs (1ST) on (27th July)

Total Phase begins at 01:00 hrs (1ST) (28 July)

Greatest eclipse is at 01:52 hrs (IST)

Total phase ends at 02:43 hrs (IST)

Partial phase finally ends at 03:49 hrs (1ST).

Entire eclipse will be visible in India. Lunar eclipses can be observed without telescopes, from an open space. Observing a lunar eclipse with naked eye will not cause harm.




Another total eclipse of the Moon can be seen from India on the night of 21st January 2019 to early hours of 22nd January 2019.

The Moon will be completely covered by the Earth’s umbra for 103 minutes, making this eclipse the longest total lunar eclipse of the 21st century.

The next time we will see a similarly long eclipse will be on June 25/26, 2029 total lunar eclipse, where totality will last for 102 minutes. A Micro Full Moon takes place when the Moon is at its farthest distance from the Earth in its elliptical orbit (apogee). On July 27, 2018, the Moon will reach its apogee the point. This Full Moon may look slightly smaller and less bright than a normal Full Moon hence it is known as micro moon. A Micro Full Moon also takes longer to move across the Earth’s shadow compared to a Full Moon that is eclipsed closer to the Earth. This is why the duration of this eclipse will be longer than any other lunar eclipse in this century.

According to scientists, the longest possible theoretical duration for totality during a lunar eclipse is 107 minutes. The total lunar eclipse on July 16/17, 2000, came close at 106 minutes and 24 seconds.

Subject to clear sky conditions, B.M. Birla planetarium will be making arrangements for the public to view the event at Periyar Science and Technology Centre Campus, Gandhimandapam Road, Chennai-25 on from 11 p.m. of 27th July 2018 to 4.00 a.m of 28th July 2018. There is no entry fee.

A rare event of closest approach of the Planet Mars near the Earth

 

Planet Mars near the Earth
Planet Mars near the Earth

The Planets which lie within the Earth’s orbit are called inferior planets and we call the planets which lie beyond the Earth’s orbit the superior planets. A superior planet may make any angle up to 180 degrees with the Sun as viewed from the Earth. When a planet moves to a point 180 degrees away from the Sun, that is, at the diametrically opposite side of the Sun when viewed from the Earth, the planet is said to be at opposition. This is practically advantageous time to observe the planet, for it is near this configuration that the planet makes its closest approach to the Earth, is fully illuminated by the Sun and as a result appear largest and brightest. It is visible all night because it rises at sunset and sets at sunrise.

Mars is the first of six superior planets. Once in about 26 months, the Earth overtakes the red planet Mars in its orbit, that is, Mars comes to opposition. The orbit of Mars is significantly more elliptical than Earth’s with an eccentricity of 0.09. Because of this, the distance between Earth and Mars, during Mars oppositions in every 26 months, keeps changing. On the average at its most distant point, Mars is at about 38 crore kilometres from the Earth and the theoretical – closest approach that Mars can make to Earth is 5.4 crore kilometres. At the time of opposition, the Earth and Mars will lie nearly in a straight line with respect to the Sun.




One such opposition will occur on 27th July 2018 at 10:37 hrs (IST) with an apparent planetary disk diameter of 24.3″ arcsec. Mars will appear bright and big for a few weeks during this period. Mars is not necessarily closest at opposition because of its elliptical orbit. Mars is still moving toward perihelion gradually getting closer to the Sun each day. Closest approach occurs at 13:21 hrs (IST) on July 31, 2018 with an apparent planetary disk diameter of 24.3″ at a distance of 5,75,90,630 km. Again, on September 15, 2035, Mars will come this close. On that day it will be at a distance of 5.69 crore km. Earlier, on August 27, 2003, Earth approached closer to Mars than at any times in the past 59,542 years. On that day Mars was at a distance of 5.5 crore k.m.

The last Mars opposition occurred on May 22, 2016 at a distance of about 7.6 crore km but this time on July 27, 2018 at a distance of about 5.76 crore km. Next Mars opposition will occur on October 13th, 2020 at that time it will come to a distance of 6.21 crore km. The distance at close approach varies between about 5.4 crore and about 10.3 crore km due to the planet’s elliptical orbit, which causes variation in angular size.

The average time between the successive oppositions of Mars, its synodic period, is 780 days; but the number of days between the dates of successive oppositions can range from 764 to 812. As Mars approaches opposition it begins a period of retrograde motion, which makes it appear to move backwards in a looping motion relative to the background stars. The duration of this retrograde motion is about 72 days. To view the Mars again this big and this bright we will have to wait till September 15, 2035. B.M.Birla Planetarium is making arrangements for the public to view the planet Mars through the telescopes, subject to cloudless clear sky conditions, during 25th — 31st July 2018, between 7 p.m. and 9 p.m. at Periyar Science and Technology Centre Campus, Gandhimandapam Road, Chennai-25.

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