Heads up, skywatchers! Did you know there’s a night set aside each year to celebrate and observe our Moon? International Observe the Moon Night has been held annually since 2010. This year it’s Saturday, Oct. 5.
This year also offers an opportunity to celebrate lunar exploration at a time when we are preparing to land American astronauts, including the first woman and the next man, on the Moon by 2024. Through the NASA’s Artemis lunar exploration program, we will use innovative new technologies and systems to explore more of the Moon than ever before, and use that knowledge to take the next giant leap, sending astronauts to Mars.
The International Observe the Moon Night is happening Oct. 5!
In the wake of the beautiful Harvest Moon seen Sept. 14, Earth’s satellite now enters its waning phase, shrinking slice by slice into a visible semicircle as the rotating Earth spins around the Sun and its shadow is cast past us onto the Moon.
This period of waxing or waning is commonly known as a “gibbous” period, a term meaning “convex” or “rounded.” The term originated in the 15th century, though the Oxford English Dictionary suggests it was first applied to describe the Moon in 1690.
Gradually, over the coming month, the Moon will cycle toward its next full period – the Hunter’s Moon, also known as the Blood Moon or Sanguine Moon, due in mid-October. Various Native American tribes gave the Moon this name to reflect the falling leaves of autumn and the fattening of deer and other animals to prepare for the winter to come.
Speaking of coming events, the International Observe the Moon Night is happening Oct. 5! Learn more about NASA’s plans and how you can join in the fun here.
Take a moment this weekend to gaze at the beautiful Harvest Moon! The Moon will appear full Thursday night through Sunday morning. Early Saturday morning, Sept. 14, will mark the actual full Moon.
The Harvest Moon gets its name from agriculture. In the days before electric lights, farmers across the Northern Hemisphere depended on bright moonlight to extend the workday beyond sunset. It was the only way they could gather their ripening crops in time for market. The full Moon closest to the autumnal equinox became “the Harvest Moon,” and it was always a welcome sight.
The term became further entrenched in popular culture thanks to a 1903 pop tune called “Shine on Harvest Moon.”
A Harvest Moon inflated by the moon illusion — a common phenomenon with full moons seen close to the horizon, where familiar Earth objects such as trees or buildings lend the Moon a false sense of size — is simply beautiful to view, but even more so to the farmers gathering their crops in on those cool autumn evenings.
The Perseid meteor shower is here! Perseid meteors, caused by debris left behind by the Comet Swift-Tuttle, began streaking across the skies in late July and will peak on the night of August 12.
The Perseid meteor shower is often considered to be one of the best meteor showers of the year due to its high rates and pleasant late-summer temperatures. This year’s shower, however, has unfortunate circumstance of having a full Moon right at the shower peak, reducing the meteor rates from over 60 per hour down to 15-20 per hour. But the Perseids are rich in bright meteors and fireballs, so it will still be worth going out in the early morning to catch some of nature’s fireworks.
WHEN SHOULD I LOOK?
Make plans to stay up late or wake up early the nights of August 11 to 12 and August 12 to 13. The Perseids are best seen between about 2 a.m. your local time and dawn. On the night of the 11th, the Moon will set around 3 AM, giving you about an hour of dark sky to catch the shower. However, the rates will be lower than on the peak, so don’t expect more than 20 per hour, even without the Moon. On the night of the peak (August 12-13) you will only have a scant few minutes of dark sky between moon set and twilight – not much time to see Perseids.
If those hours seem daunting, not to worry! You can go out after dark, around 9 p.m. local time, and see Perseids. Just know that you won’t see nearly as many as you would had you gone out during the early morning hours.
How can you see the Perseids if the weather doesn’t cooperate where you are? A live broadcast of the meteor shower from a camera in Huntsville, AL (if our weather cooperates!) will be available on the NASA Meteor Watch Facebook starting around 8 p.m. ET and continuing until the early hours of August 13. Meteor videos recorded by the NASA All Sky Fireball Network are also available each morning; to identify Perseids in these videos, look for events labeled “PER.”
WHY ARE THEY CALLED PERSEIDS?
All meteors associated with one particular shower have similar orbits, and they all appear to come from the same place in the sky, called the radiant. Meteor showers take their name from the location of the radiant. The Perseid radiant is in the constellation Perseus. Similarly, the Geminid meteor shower, observed each December, is named for a radiant in the constellation Gemini.
HOW TO OBSERVE PERSEIDS
If it’s not cloudy, pick an observing spot away from bright lights, lay on your back, and look up! You don’t need any special equipment to view the Perseids – just your eyes. (Note that telescopes or binoculars are not recommended.) Meteors can generally be seen all over the sky so don’t worry about looking in any particular direction.
While observing this month, not all of the meteors you’ll see belong to the Perseid meteor shower. Some are sporadic background meteors. And some are from other weaker showers also active right now, including the Alpha Capricornids, the Southern Delta Aquariids, and the Kappa Cygnids. How can you tell if you’ve seen a Perseid? If you see a meteor try to trace it backwards. If you end up in the constellation Perseus, there’s a good chance you’ve seen a Perseid. If finding constellations isn’t your forte, then note that Perseids are some of the fastest meteors you’ll see!
Pro tip: Remember to let your eyes become adjusted to the dark (it takes about 30 minutes) – you’ll see more meteors that way. Try to stay off of your phone too, as looking at devices with bright screens will negatively affect your night vision and hence reduce the number of meteors you see!
It’s the first day of summer here in the Northern Hemisphere, and the first of winter in the Southern Hemisphere. Why the difference? It’s all about Earth’s tilt!
Earth’s axis is an imaginary pole going right through the center of Earth from “top” to “bottom.” Earth spins around this pole, making one complete turn each day. That is why we have day and night, and why every part of Earth’s surface gets some of each.
Earth’s axis is always tilted 23.5˚ with respect to the Sun. Today, the north pole is tipped toward the Sun, and the south pole is tipped away from the Sun. The northern summer solstice is an instant in time when the north pole of the Earth points more directly toward the Sun than at any other time of the year.
The solstice—meaning “sun stands still” in Latin—occurs at 10:54 a.m. CDT.
Happy equinox, Earthlings! March 20 marks the spring equinox, one of two seasonal markers in Earth’s year-long orbit when the Sun appears to shine directly over the equator, and daytime and nighttime are nearly equal lengths–12 hours–everywhere on the planet.
It’s the start of astronomical spring in the Northern Hemisphere, meaning more sunlight and longer days. From here until the beginning of fall, daytime will be longer than nighttime as the Sun travels a longer, higher arc across the sky each day, reaching a peak at the start of summer. It’s just the opposite in the Southern Hemisphere, where March 20 marks the fall equinox.
What’s more? The first full Moon of spring will rise tonight, lighting the skies on the equinox. Usually, a full Moon arrives a few days to weeks before or after the equinox. It’s close, but not a perfect match. Tonight’s full Moon, however, reaches maximum illumination less than four hours after the equinox. There hasn’t been a comparable coincidence since the spring equinox in 2000.
And because the Moon is near perigee, it qualifies as a supermoon–the third and final of 2019. It’s not a big supermoon, so you won’t really be able to see the difference between this full Moon and any other one with your eyes. But keep an keep an eye on the Moon as it rises and creeps above the eastern skyline. A low-hanging Moon can appear strangely inflated. This is the Moon illusion at work.
Super or seemingly not, it’s a rare celestial coincidence to usher in springtime.
“The second supermoon of 2019 happened Feb. 19. The third of 2019 will happen March 19. But what’s a supermoon? We asked NASA astronomer Mitzi Adams what’s really going on here. Here’s her answer!”
Like the orbits of all bodies in the solar system, the Moon’s orbit around Earth is not circular, it has an oval or elliptical shape, with Earth slightly offset from the center. As a result, there are two distance extremes of each orbit: closest approach, known as perigee, and the farthest, or apogee. When the Moon is at closest approach and within a day or so of being full, it is called a supermoon because the Moon will be at its brightest and largest.
For the supermoon on Feb.19, the Moon will be full only six hours after it reaches the perigee distance of its orbit, making it the brightest and largest full Moon of the year. A supermoon also occurred in January with a slightly more distant perigee, a mere 362 miles (583 kilometers) farther away, but 14 hours after the full Moon. However, January’s supermoon included a total lunar eclipse seen in all of North and South America. The third and last supermoon of the year will happen March 19, when the perigee distance will be reached a day and five hours before the full Moon (see the table below for details).
Time Before or After Full Moon
222,043 miles (357,344 km)
15 hours after
221,681 miles (356,761 km)
6 hours before
223,308 miles (359,380 km)
1 day, 5 hours before
To watch tonight’s supermoon, or any full Moon, simply look for the Moon to rise in the east as the Sun sets in the west. The Moon will look extremely large when it rises and sets. This “Moon illusion” happens when the Moon is close to the horizon and there are objects within our line of sight such as trees or buildings. Because these relatively close objects are in front of the Moon, our brain is tricked into thinking the Moon is much closer to the objects that are in our line of sight. At Moon rise or set, it only appears larger than when it is directly overhead because there are no nearby objects with which to compare it. You can check this. When the Moon rises, hold a coin at arm’s length so that the coin covers the Moon. Repeat this throughout the evening and you will see that the Moon’s size does not change.
As it rises on Feb. 19, the Moon will be in the constellation of Leo. However, since the Moon is so bright, you may have trouble seeing the bright star Regulus, which is at the end of the “backwards question mark” that makes Leo easy to spot.
Looking more or less directly overhead, you could see the famous constellation Orion the Hunter with bright stars Betelgeuse, a reddish star, and Rigel, a bluish star. With a telescope or binoculars, you might be able to pick out the Orion nebula just below the belt stars of Orion, Alnitak, Alnilam, and Mintaka.
To the west of Orion you should be able to spot reddish Mars.
As we observe this supermoon, keep in mind that 2019 marks the 50th anniversary of a great technological feat – humans travelled to the Moon, walked on its surface and returned safely to Earth. Twelve people walked on the Moon. Neil Armstrong and Buzz Aldrin were the first two, but let us not forget the other ten: Alan Bean, Charles “Pete” Conrad, Edgar D. Mitchell, Alan Shepard, Dave Scott, James Irwin, John Young, Charles Duke, Eugene “Gene” Cernan and Harrison Schmitt. These men, along with the command module pilots Michael Collins, Dick Gordon, Stu Roosa, Al Worden, Ken Mattingly, Ron Evans and the multitudes of support staff back on Earth, fulfilled a dream of exploring our nearest neighbor in space. As NASA and its commercial and international partners plan to return the Moon over the next decade with a long-term continued presence, the list of Moon walkers will surely include women, as well.
Well over 100 people in California, Nevada, Arizona and Oregon observed a fireball at 5:35 p.m. PST Dec. 19. This event was unusual not for the brightness of the fireball—similar to that of a crescent Moon—but for the persistent train left behind after the object ablated. This persistent train lasted for minutes (compared to the one second duration of the fireball) and was caused by sunlight reflecting off dust particles left behind by the meteoroid as it broke apart in Earth’s atmosphere. Upper atmosphere winds distorted the train over time, giving it a curvy, “corkscrew” appearance.
An analysis of the eyewitness accounts indicates that the meteor first became visible at an altitude of 48 miles over the Pacific Ocean some 50 miles west of the entrance to San Francisco Bay. Moving west of south at 63,000 miles per hour, it managed to survive only a second or so before ablating and breaking apart at an altitude of 34 miles above the ocean.
The second week of December heralds the beginning of the strongest meteor shower of the year – the Geminids. It’s a good time to bundle up, go outside and watch one of Mother Nature’s best sky shows!
The Geminids are active every December, when Earth passes through a massive trail of dusty debris shed by a weird, rocky object named 3200 Phaethon. The dust and grit burn up when they run into Earth’s atmosphere in a flurry of “shooting stars.”
Phaethon’s nature is debated. It’s either a near-Earth asteroid or an extinct comet, sometimes called a rock comet. There is another object – an Apollo asteroid named 2005 UD – that is in a dynamically similar orbit to Phaethon, prompting speculation that the two were once part of a larger body that split apart or collided with another asteroid.
Most shower meteors are shed by comets when their orbits take them into the inner Solar System, but the Geminids may be the debris from this long-ago breakup or collision event. When you consider that the Geminid meteor stream has more mass than any other meteor shower, including the Perseids, whatever happened back then must have been pretty spectacular.
So what do potential Geminid watchers need to do this year?
It’s pretty simple, actually. The nearly First Quarter Moon sets around 10:30 p.m. local time, so wait until then to go out – the light from the Moon washes out the fainter meteors, which are more numerous. Find the darkest place you can, and give your eyes about 30 minutes to adapt to the dark. Avoid looking at your cell phone, as it will mess up your night vision. Lie flat on your back and look straight up, taking in as much sky as possible. You will soon start to see Geminid meteors. As the night progresses, the Geminid rate will increase, hitting a theoretical maximum of about 100 per hour around 2 a.m.
Bear in mind, this rate is for a perfect observer under perfect skies with Gemini straight overhead. The actual number for folks out in the dark countryside will be slightly more than 1 per minute. Folks in suburbs will see fewer, 30 to 40 per hour depending on the lighting conditions. And those downtown in major cities will see practically nothing – even though the Geminids are rich in beautiful green fireballs, the lights of New York, San Francisco, or Atlanta will blot even them out. Dark clear skies are the most important ingredient in observing meteor showers.
And while you’re scanning the sky for Geminids, you might notice a small, faint “ghostly” green patch in the constellation of Taurus – that’s Comet 46P/Wirtanen, which will be making its closest approach to Earth (7 million miles) for the next 20 years. We are actually going to have a comet visible to the unaided eye this holiday season!
Comets are notoriously unpredictable beasts, but if Wirtanen continues to follow its current brightening trend, it may reach a peak magnitude of around +3 (about as bright as a star in the handle of the Little Dipper) a couple of days past the Geminid peak, on December 16. Binoculars or a small telescope are good for taking a peak at Wirtanen, so bring them along for your night of Geminid watching. A green comet to complement the green fireballs!