Do not sleep on the lunar eclipse when exploring celestial movements
Sam RoykaWith so much focus on the April 8 solar eclipse, not as much is said about its shadowy sibling, the lunar eclipse. Solar and lunar eclipses always come in pairs. A lunar eclipse occurs when the Earth’s shadow covers the moon. The darkest part of this shadow is called the ‘umbra.’
Just like with the sun, lunar eclipses can be partial or total, depending on the alignment of the astronomy. As the moon orbits the Earth, it moves into the penumbra, showing a partial eclipse. It is not until it reaches the darkest part of the shadow that the eclipse becomes total. This state, called ‘totality,’ lasts a number of minutes as the moon moves through.
“If the sun were hollow, you could put over a million Earths inside of it,” said Astrophysicist Fred Espenak at a Feb. 8 discussion at Indiana’s Vincennes University.
This chart is not to scale. In real life, the sun’s diameter is 109 times the diameter of the Earth, and the moon is about one-quarter the size of the Earth, Espenak said. This ratio of size is an important part of the recipe for an eclipse. Because of complex mathematical relationships and distances that perfectly align, we are able to see total eclipses of both kinds – not including those of the heart. (THE VISTA/SAM ROYKA)
Lunar eclipses are also called ‘blood moons’ because of the shadow’s characteristic red tint. This color exists because of its place on the light spectrum! Since Earth’s atmosphere partially blocks the sunlight, blue light scatters, leaving only the red left behind.
Here in another graphic, the visible light spectrum is only a part of the energy we can see. The color of light changes by how fast it vibrates, which is the same thing as how long the energy wave is – in other words, its wavelength.
This illustration of the electromagnetic spectrum shows that the light we can perceive is just a tiny part of the frequency range. Do you see how blue is on the left and red is on the right? This is because blue light moves faster and red moves slower. (PROVIDED/PHILIP RONAN)
They always occur when the moon is full, so the contrast is most visible between the bright full moon then eclipsed in total shadow. The next partial lunar eclipse will be September 18, 2024, and this is notable because it is the end of an 18-year eclipse cycle.
The Saros Cycle, pronounced SAE-rohs, is the official name for the period of an eclipse cycle. One Saros is approximately 18 years, 11 days, 8 hours long according to Espenak. It may vary by a few days depending on the number of leap years. This partial eclipse is the last one of Saros Cycle 118.
According to NASA, the next time to get a full-totality lunar eclipse visible in the Americas will be March 3, 2026. NASA keeps track of all total lunar eclipses at its official eclipse website, at https://eclipse.gsfc.nasa.gov/LEdecade/LEdecade2021.html which provides information on lunar eclipses until 2030.