A total lunar eclipse occurs when the earth slips from the sun and casts a reddish orange to deep red shadow on the moon.
For this reason, the astronomical event is often referred to as the blood moon. People in the Earth's eastern hemisphere can observe the longest lunar eclipse of the 21st century from 19:30 Universal Time (UT) on Friday, July 27th.
But suppose you were an astronaut who happens to be on the surface of the moon during a total lunar eclipse, and you look back home. What would you see?
NASA's Science Visualization Studio has illustrated the answer to this question with an animated video.
For someone on the moon during a lunar eclipse, the earth seems to be surrounded by a bright red ring of fire.
The image above is extracted from the animation of NASA, which depicts the exact appearance of the Earth and the Moon during the total lunar eclipse that took place on the September 27, 2015 took place.
But apart from the position of the continents, this week's lunar eclipse will be more or less the same from the moon's perspective.
Here is the reason.
What gives total lunar eclipses an orange-red color
Total lunar eclipses and total solar eclipses are essentially the opposite of each other.
However, their appearance is very different (whether you are watching from Earth or their natural satellite).
During a total eclipse, the Moon passes between the Earth and the Sun, casting a small, dark shadow over our planet. For those who watch the earth, the ring of sunlight that surrounds the moon looks colorless because the moon has no atmosphere. (Atmospheres, like glass lenses, can break sunlight.)
But the earth is surrounded by a layer of air, and this lenticular refraction is ultimately the reason why lunar eclipses make the moon look orange-red.
By volume, about 80% of the Earth's atmosphere is nitrogen gas, or N 2 and most of it is oxygen gas or O 2 . Together, these gases absorb white sunlight – a mixture of all the colors in the spectrum – and scatter blue and purple colors. Human eyes are much more sensitive to blue than to purple, which is why the sky looks blue and the sun turns yellow in daylight.
During a sunrise or sunrise, sunlight reaching our eyes has transmitted much atmospheric gas, and this effectively filters out the blues, making the light appear orange or even red.
Something similar happens during a lunar eclipse. The Earth's atmosphere bends and focuses the sunlight into a glowing, cone-shaped shadow called Umbra.
The red color is never quite the same from one lunar eclipse to the next due to natural and human activities affecting the Earth's atmosphere.
"Pollution and dust in the lower atmosphere tend to dampen the color of the rising or setting sun, while fine smoke particles or tiny aerosols that are carried to high altitudes during a large volcanic eruption can deepen the color to an intense shade of red David Diner, a planetary scientist at NASA's Jet Propulsion Laboratory, wrote in a blog post in 2010.
What Earth Looks Like From The Moon During A Total Lunar Eclipse
About 240,000 miles away on the Moon, the Earth would look pretty stunning during a lunar eclipse.
"If you stood on the lunar surface during a lunar eclipse, you would see the sun behind Seeing earth rise, "Diner wrote." They would have the broken and streaked Observe the sun's rays as they pass the atmosphere around our planet. "
On the moon, you can see the sunrise and sunset of the earth in a loop about 25,000 miles long. And on the ground around you, usually gray moondust or regolith would look a bit orange-red.
The color-stained umbra of Earth is always out there – if you had enough money and a spaceship, you could fly in anytime.
The Moon's slightly inclined orbit, however, means that it only twice passes through the shadow of our planet every 11 months.
Where and when the total lunar eclipse can be seen on Friday
The coming eclipse will take place during a so-called "micro" moon – the opposite of a super-moon. This happens because the moon's orbit is not perfectly circular, so sometimes it appears larger and sometimes smaller during its approximately 29-day orbit around the earth. In this case, it will look a little smaller.
North America will be out of luck during the lunar eclipse, as the moon will be below the horizon. However, you can still follow the phenomenon live in a webcast.
If the weather cooperates, most of East Africa, the Middle East, and Central Asia should see the full and total lunar eclipse. Scientists in the Antarctic should also have a great view.
Europe, East Asia, Australia, Indonesia and other regions will enjoy a partial lunar eclipse, with the moon partially passing through the earth's shadow.
The partial solar eclipse begins when the moon first touches the semi-shade of the earth. According to NASA, this will happen on July 27 at 17:14.
The Total Solar Eclipse – when the Moon is completely in the red colored Umbra of Earth – begins at 19:30 UT and ends at 21:13 UT. That's a full 1 hour 43 minutes, which is only four minutes after the longest total lunar eclipse possible, according to EarthSky.
The partial eclipse is resumed immediately after the moon begins to leave the shadow of the earth. The whole event will be over at 23:28 UT (which might be technically early July 28, depending on where you live).
See the NASA animation of a total lunar eclipse from the moon below.