Admin and Founder of ‘The Secrets Of The Universe’ and former intern at Indian Institute of Astrophysics, Bangalore, I am a science student pursuing a Master’s in Physics from India. I love to study and write about Stellar Astrophysics, Relativity & Quantum Mechanics.
Mars is in news these days. A lot! The Red Planet is gearing up for its closest approach to the Earth next month. It is getting brighter day by day. It has already outshone Sirius, the brightest star in the night sky. By the end of September, Mars will be brighter than Jupiter. But this is not the only reason why Mars is in the news. Mars is going to be occulted by the Moon for the second time in just 28 days. Although the occultation is visible from a small part of the world, others can enjoy the sight of the close proximity of the two celestial objects.
What Is An Occultation?
An occultation is an astronomical event that occurs when one object is hidden by another object that passes between it and the observer. In other words, when the object in the foreground blocks the view of the object in the background, it is called an occultation.
But how is it different from the transit and an eclipse? Well, a transit occurs when the object in the foreground does not completely hide the object in the background. For example, when Mercury or Venus passes in front of the Sun as seen from the Earth, the event is known as a transit.
An eclipse is an astronomical event when a celestial body totally or partially disappears from the view of the observer either by an occultation or a transit. In simple words, if a shadow is cast onto an observer during an occultation or transit, it is called an eclipse.
The term occultation is mostly used when the Moon passes in front of an astronomical object. The Moon’s orbit is inclined slightly with respect to the ecliptic meaning any stars with an ecliptic latitude of less than about ± 6.5 degrees may be occulted by it. Since the planets also lie in the ecliptic, they are often occulted by the Moon.
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Lunar Occultation of Mars In September
On September 6, The Moon will pass in front of Mars, creating a lunar occultation visible from parts of South America, Africa, and Southern Europe. For the rest of the world, the two will appear very close to each other.
Lunar occultations are only ever visible from a small fraction of the Earth’s surface. Since the Moon is much closer to the Earth than other celestial objects, its exact position in the sky differs depending on your exact location on Earth due to its large parallax. The position of the Moon as seen from two points on opposite sides of the Earth varies by up to two degrees, or four times the diameter of the full moon.
This means that if the Moon is aligned to pass in front of a particular object for an observer on one side of the Earth, it will appear up to two degrees away from that object on the other side of the Earth.
For the rest of the world, the Moon will appear to pass very close to the Red Planet in the constellation of Pisces.
The map below from in-the-sky shows the places where the occultation can be seen from Earth.
Occultations of bright stars and planets typically occur a few times per year, often clustering with several occultations of the same object in successive months, since the Moon traces roughly the same path across the sky each month. These clusters come to an end after a few months, when gradual changes in the Moon’s orbit change the Moon’s path across the sky. Alternatively, in the case of planets, the planet’s own movement will eventually carry it away from the Moon’s path.
In 2020, there will be two more Lunar occultations. The Moon will again pass in front of Mars on October 3. Later, on December 12, the Moon will pass in front of Venus.
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