For those looking up at the sky tonight in North America, you may be feeling something missing – the moon! That’s because July 31 marks a lunar event called the “black moon” which is like the second new moon to occur in a single calendar month. A new moon is the phase of the moon where it is invisible, with the bright part of the moon looking away from us.
Walter Freeman is an assistant teaching professor in the physics department at Syracuse University College of Arts and Sciences. He says that astronomical events such as the black moon are catching people’s attention as it is a kind of bridge between two of humanity’s greatest achievements: fiction and mythology, and science.
Dr Freeman answers five questions about “black moon: 31 July. ”
What is a “black moon” and can you explain the science behind it?
“A ‘black moon’ is a second new moon which takes place in a single calendar month. This is no different from any other new moon from a scientific point of view. When the Moon is on the same side of the Earth as the Sun, the face of the moon which receives sunlight is marked from us, and we do not see it; the face of the moon which is told to us is overshadowed, so that we may not see it. This is a ‘new moon’, and occurs once every 29.5 days. Our months are a little longer than this, so sometimes we get two of these per calendar month. This is because the designers of the Gregorian calendar we use wanted all the years to be the same length, and have extended the “months” by just over 29.5. days until twelve months adds up to one year. So, if a new moon happens near the beginning of a calendar month, the next one happens before it is over. Science is not here; it’s just an artifact of how we keep time. ”
How is it different from other lunar events, such as a super wolf blood moon?
“A ‘blood moon’ is something of astronomical interest: a lunar eclipse, where the Earth’s shadow falls on the Moon. The term ‘blood moon’ comes from the fact that red light from the Sun leaps around the edges of the Earth even at a lunar eclipse. ”
How do you see it?
“Nothing to see! A new moon is the phase of the Moon where it is invisible since the lit part looks away from us.
“However, because you can’t see the Moon you can see the stars, the planets and the Milky Way better. When the Moon is above the horizon, the moonlight drowns out the brightest stars and planets. When the Moon is near new, it is also largely on the horizon at night. So this time of month, where the Moon is almost fresh, is a great time to keep an eye on all the other stuff in the night sky.
“In particular, we have a great view of Jupiter right now in the southern skies, visible after dark. If you look at Jupiter with binoculars, a small telescope, or a large telephoto lens, you will see Jupiter’s four largest branches; they are the only ones who saw Galileo four hundred years ago that led him to believe that the sun, not the Earth, was at the heart of the solar system. ”
Is this type of lunar event rare?
“A new moon happens every 29.5 days, so – speaking celestially – this is very common! Two new moons occur in one month when the first new moon falls in the first day and a half of a 31-day month; this happens every year or two. ”
Why do you think these lunar events capture the attention of so many people?
“Astronomical events capture people’s attention because we have always been telling stories and making myths about things in the night sky. The bright red planet is named after the blood-red Mars, god of war. We named the beautiful planet seen in the morning and evening after Venus, the Roman goddess of beauty. Now we know more, of course: Mars is red because it has rust on its surface, and Venus is actually a sulfurous hell scene hot enough to melt lead with the effect of a runaway greenhouse. But knowing the planets and stars in reality, and how they work, doesn’t mean we can’t imagine the myths.
“So I think astronomy grabs people’s attention because it’s a kind of bridge between two of humanity’s greatest achievements: fiction and mythology, and science. . ”