Just before 4 a.m. Wednesday, the moon will appear unusually bright and large above the western horizon before shifting from gold to red to inky gray-black as it passes into the Earth鈥檚 shadow.
The rare lunar event, dubbed a 鈥渟uper blue blood moon,鈥� marks the unusual overlap of three celestial occurrences: a听鈥渂lue moon,鈥� or second full moon in a calendar month; a 鈥渟upermoon,鈥� in which the moon is near its closest point to Earth in its orbit; and a total lunar eclipse, when the earth casts a shadow on the moon.
鈥淚t will appear about 6 percent larger than average and significantly brighter than a typical full moon just before the eclipse begins around 4 a.m.,鈥� explains Paul Hayne, an assistant professor in the department of astrophysical and planetary sciences听and researcher with the Laboratory for Atmospheric and Space Physics.
鈥淭hen, as the moon passes into Earth鈥檚 shadow, the sunlight refracted through our atmosphere creates a warm reddish hue on the lunar surface. It鈥檚 similar to the colors of a sunset, because we are seeing the effect of our atmosphere filtering out the blue light and letting the red light pass through.鈥�
In that moment of total eclipse, the temperature on the moon also plummets about 100 degrees, offering a rare opportunity for scientists to observe the lunar surface as it cools.
Hayne will spend the morning at Haleakala Observatory on the island of Maui, observing via a heat-sensing camera.
鈥淭he whole character of the moon changes when we observe with a thermal camera during an eclipse,鈥� he said. 鈥淚n the dark, many familiar craters and other features can鈥檛 be seen, and the normally non-descript areas around some craters start to glow because the rocks there are still warm.鈥�
He offers the following tips for those eyeing the super blue blood moon from Colorado:
Head east
Since the moon will be setting in the west during the eclipse, the farther east you go the more of it you鈥檒l be able to see.
Get up early
The moon will be its brightest right before the eclipse begins, around 4 a.m. The eclipse will peak about 6:30 a.m., but for some in the Foothills, it will be obstructed by the mountains by then.
Watch it all
鈥淥ver the course of about two hours, the moon will go from bright gold to red and then inky gray-black,鈥� said Hayne.
Use a telephoto and light meter
鈥淪ince the moon will be much brighter than anything else in the sky or foreground, it helps to use a light meter to reduce the exposure so that the Moon itself is not overexposed,鈥� he said. 鈥淎s the eclipse progresses, the exposure will need to be increased to compensate for the lower brightness.鈥�
