This is a question many people ask when many parts of the world are witnessing a lunar eclipse that happens once every 500 years.
A lunar eclipse is an astronomical phenomenon that occurs when the Sun, Earth, and Moon are aligned or approximately aligned. At this time, part or all of the Moon will not receive light from the Sun because it is obscured by the Earth, causing a lunar eclipse.
When the Moon is in the entire shadow of the Earth, light from the Sun will not be able to reach the Moon. This is a total lunar eclipse.
|When a lunar eclipse occurs, the Moon will turn dark red.|
During a lunar eclipse, the Moon usually turns dark red. The reason is because light from the Sun, even though it is blocked by the Earth, still bends and passes through the Earth’s atmosphere to reach the Moon.
Earth’s atmosphere filters out wavelengths shorter than blue and allows red wavelengths to pass through. Red wavelengths pass through Earth’s atmosphere toward the Moon and give the object a dark red color. That’s why a total lunar eclipse is often called a “Blood Moon”.
With a partial lunar eclipse, this occurs when the Sun, Earth, and Moon are roughly in a straight line. At that time, part of the Moon will not receive direct light from the Sun. The Moon is partially vacated by the Earth’s own shadow.
|A lunar eclipse occurs when the Sun, Earth, and Moon are aligned and the Moon is obscured by the Earth’s shadow.|
A partial lunar eclipse can occur before and after a total lunar eclipse, when the celestial bodies are approaching or just after forming an alignment.
In addition to total and partial lunar eclipses, there is another phenomenon known as a penumbral lunar eclipse. That’s when the Moon moves into the Earth’s umbra. The light from the Moon will then dim and no longer be as bright and clear as usual.
During the lunar eclipse taking place tonight (November 19, Vietnam time), only 97% of the Moon’s area is covered by the Earth’s shadow. Therefore, this is a partial lunar eclipse. However, with a large coverage ratio, this partial lunar eclipse is not much different from a total lunar eclipse.
People across the country will have the opportunity to observe the partial lunar eclipse between the time of moonrise (17:14″ in Hanoi and 17:26″ in Ho Chi Minh City) until 17:47″. Following this period, the penumbral lunar eclipse will take place for more than 1 hour (ending at 19:03″).
In the semi-dark phase, the Moon will not be much different from the normal full moon, especially in urban areas, where it is polluted by urban light.
How to observe the partial lunar eclipse on the evening of November 19
People in Vietnam can observe the final phase of a partial lunar eclipse, even if only for a relatively short period of time.