Get ready: The moon is about to blush

Maybe the moon has a secret crush on Earth, or perhaps it's up to some mischief as it orbits our planet. Whatever the reason, it will be blushing again in the early morning hours of Tuesday, March 3.

Yes, a "Blood Moon" - a total lunar eclipse - is on the way. The University of Delaware's Bennett Maruca, associate professor of physics and astronomy, explains why the moon turns red, how to get the best view of this celestial event, and why some folks call March's full moon the "Worm Moon."

Q: What is a total lunar eclipse - how does it work?

Maruca: A lunar eclipse occurs when the moon passes into the shadow of the sun. This happens when the sun, Earth and moon line up, with Earth in the middle. In a total lunar eclipse, the moon passes completely into the central portion of Earth's shadow. If you were on the near-side of the moon during a total lunar eclipse, the entire surface of the sun would be blocked by Earth's surface.

Q: Why does the moon turn red?

Maruca: During a total lunar eclipse, the only light that reaches the surface of the moon is refracted through Earth's atmosphere, which essentially acts like a lens. Light is a wave, and every color of the rainbow has a different wavelength - red the longest and violet the shortest. As it happens, short-wavelength light is much more likely to be scattered when it passes through the atmosphere. This is why the sky looks blue during the day - the blue and violet sunlight passing overhead is scattered off its path, and some of it reaches our eyes. The red light isn't scattered nearly as much, so more of it can pass through the atmosphere and, during a total lunar eclipse, reach the moon's surface.

Q: When and where can the eclipse be seen?

Maruca: Weather permitting, a lunar eclipse is visible from anywhere on Earth where the moon is above the horizon. For this eclipse, that will include most of the United States (although the eastern parts will miss the moon coming out of eclipse), the Pacific Ocean and parts of Australia and eastern Asia. In Delaware, during the lunar eclipse, the moon will be low in the western sky. Totality will begin around 6 a.m. for us, just about 30 minutes before the moon sets, so the moon will be very close to the horizon. Try to watch from a location with a clear view of the western horizon - no trees or buildings. Getting away from light pollution always helps but is less essential since the moon is so bright in the sky.

Q: Are any safety precautions/special equipment needed to view or photograph it?

Maruca: Unlike during a solar eclipse, no special safety precautions are necessary - it's perfectly safe to look at the moon (in or out of a lunar eclipse) with the naked eye. A pair of even low-power binoculars will certainly help show the moon in more detail. For photographing the moon, I would recommend a camera with some optical zoom - the moon is only about 0.5 degrees across. Because of the low lighting conditions, a tripod or other support would be helpful since a longer exposure time will be needed.

Q: How often do total lunar eclipses happen?

Maruca: On average, there are about two lunar eclipses per year, but only about one third of lunar eclipses are total. The next lunar eclipse will be in August; it will be a partial lunar eclipse, and (weather permitting) it will be visible from Delaware. The next total lunar eclipse will occur at the end of 2028.

Q: Why is this Blood Moon also called the "Worm Moon"?

Maruca: A lunar eclipse (total or partial) always occurs during a full moon. There is a long tradition of naming full moons based on when they occur during the year. Often, a name references something occurring around that time - for example, the Harvest Moon and Hunter Moon both occur in autumn. Different naming conventions exist, and many are based on the systems used by various Native American tribes. In at least one of these systems, the upcoming full moon (which will also happen to feature a total lunar eclipse) is known as the Worm Moon. It's said to mark the end of winter and the re-emergence of creatures like earthworms as the ground thaws.

Q: What's something quirky to know about the Blood Moon?

Maruca: One of my favorite things about total lunar eclipses is that it's hard to know ahead of time quite what it will look like. The moon can take on a color ranging from burnt orange to red to grayish brown. The closer the moon passes to the center of Earth's shadow, the darker the color will be. Also, since the sunlight that reaches the moon during a total solar eclipse first passes through Earth's atmosphere, atmospheric conditions - including clouds and even volcanic activity - can significantly affect the moon's color.