Studying the Moon During the Total Solar Eclipse

Studying the Moon During the Total Solar Eclipse

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May 23, 2019

The hype around the total solar eclipse mostly revolves around the sun. However, the Moon also plays an important role during this event. Viewing the total eclipse is about the Sun, the Moon, and the Earth. It is only possible when the Moon and the Sun in the sky are in a unique alignment.

Buenos Aires, Argentina

Total eclipse involves the Moon completely hiding the face of the Sun for several minutes. This offers the viewers and researchers an opportunity to see the white halo of the corona or the outer atmosphere. The Sun and the Moon are nearly perfectly aligned during the total eclipse, and the apparent size of the Sun matches the apparent size of the Moon.

A total solar eclipse is an event that happens once in about every 18 months at different locations on the planet. However, it is much less often that the eclipse occurs at the same location.

Path of Totality

On July 2, 2019, the total and partial solar eclipse will be visible in Argentina. The totality path will cross the provinces of Buenos Aires, La Rioja, Cordoba, Santa Fe, San Luis, and San Juan. People in San Juan, Rio Cuarto, Dolores, Villa Dolores, Merlo, and Lujan will be able to experience the total solar eclipse.

Along the totality path, the dark inner shadow of the Moon, known as the umbra, will travel at the speed of about 3,000 miles per hour. The umbra appears on eclipse maps as a dark oval or circle across the landscape. However, more recent visualizations reveal it as an irregular polygon with curved edges, the shape of which changes as the umbra moves across the totality path.

Recent visualizations are more accurate in representing the umbra because they account for the impact of elevation at different locations on the planet and the way the light of the Sun seeps through the valleys along the edge of the Moon.

Such level of detail can be achieved by combining the 3D mapping of the surface of the Moon, done by the Lunar Reconnaissance Orbiter of NASA, and the information on Earth elevation collected from several datasets.

Baily’s Beads

The mapping of the Moon’s terrain done by the LRO allows predicting the occurrence of Baily’s Beads, the bright flashes of light, or the diamond-ring effect. Those appear along the edges of the disk right before and right after the totality and are a result of sunlight seeping through the valleys along the Moon’s rim.

The Moon is slowly receding from the Earth, becoming 4 centimeters further away compared to the previous year. Once the Moon reaches a far enough distance, its apparent size will not be enough to cover the Sun completely. As a result, in a distant future, there will not be such an event as the total solar eclipse.

It is believed that the frequency and the number of total solar eclipses will continue decreasing. For the last time, the solar eclipse will happen in about 600 million years from now.

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