In the early morning of July 17, 2019, Vietnamese will have the opportunity to observe an interesting astronomical phenomenon of the year: a partial lunar eclipse. The following article will provide you with important information to help you observe this phenomenon.
Why is there a lunar eclipse?
A lunar eclipse is a phenomenon that occurs when the Moon, Earth, and Sun are respectively in a straight (or nearly straight) line and the Moon passes through the Earth’s shadow. At this time, the Moon faces the Sun through the Earth, so a lunar eclipse only occurs on a full moon day. Due to the distance between the Moon, Earth, and Sun, Earth’s shadow is actually divided into two regions: the umbra region and the semi-dark region.
Lunar Eclipse Explanation: When the Moon enters penumbra, a penumbral eclipse occurs. When the Moon enters its umbra (shadow), a partial lunar eclipse occurs. A total lunar eclipse occurs when the Moon is completely in shadow. Photo: NASA
Due to this division, lunar eclipses are divided into three types, corresponding to three phases. The first is Midnight Lunar Eclipse – occurs when the Moon crosses the penumbra of the Earth. At this point, the Moon is only slightly darker, so a penumbral eclipse is generally less desirable than the other two types. After passing through semi-umbra, the Moon will go into umbra. When the Moon is between these two regions, we can observe the phenomenon partial lunar eclipse. At that time, the Full Moon will be partially lost like a giant cookie with a bitten corner. And the most awaited period – total lunar eclipse – occurs when the Moon crosses the shadow of the Earth and is completely obscured. However, the Moon does not “disappear” but appears with an enchanting red light.
Partial lunar eclipse. Photo: Justin Sullivan/Getty Images
Not all full moons have a lunar eclipse. Because the plane of the Moon’s orbit is tilted 5 degrees from the ecliptic, the Moon, Earth, and Sun are not always in a straight line. The point of intersection between the apparent trajectory of the Sun and the Moon is called the nodal point, it is only when the Moon passes through this node that a lunar eclipse can be observed.
Partial Lunar Eclipse July 17, 2019
In July, the Moon will pass through the Upper Node and experience a “partial lunar eclipse.” This eclipse is visible across Europe, Africa, Central Asia and the Indian Ocean. In Vietnam, we can also observe this phenomenon.
Places where this partial lunar eclipse can be observed. Photo: In-the-sky.org
The details of the Lunar Eclipse are as follows: (Time has been converted to VN time)
• Midnight lunar eclipse begins: 01:43:51
• Start of partial lunar eclipse: 03:01:43
• extreme lunar eclipse: 04:30:44
• End of partial lunar eclipse: 05:59:39 (cannot be observed in Vietnam)
• End of the midnight lunar eclipse: 07:17:38 (cannot be observed in Vietnam)
In Hanoi, the Moon will set at 5:28 a.m., while in Ho Chi Minh City it will be 5:44 a.m., which means that we will not be able to observe the end of this eclipse.
A partial lunar eclipse at its maximum, at 04:30:44. The Moon is now very low, near the west-southwest horizon. Simulation image on Stellarium software
Unlike a solar eclipse, the viewing area of a lunar eclipse is quite large and the viewing time is relatively long. In addition, it is quite possible to observe with the naked eye. Choose a quiet location with an unobstructed view to the west and less light pollution for the most favorable observation.
When will the next lunar eclipses occur?
In 2019, there are two lunar eclipses. A total lunar eclipse occurred in January but was not observed in Vietnam, and the second was a partial lunar eclipse on July 17. In 2020, there will be four lunar eclipses, all of them in penumbra, during which Vietnam can observe lunar eclipses in January, June and November. The next observable total lunar eclipse will be on November 8, 2022.
Total lunar eclipse in July 2018. Photo: Anthony Ayiomamitis (TWAN)
Tham khảo Earthsky & Timeanddate