With the holidays right around the corner, most of us are in gift-giving mode… and one of our favorite gifts every December is the Geminid meteor shower!
This year, the peak is during the overnight hours of December 13 and into the morning of December 14. If you can’t catch the Geminids on Friday night, no worries — viewing should still be good on the night of December 14 into the early morning hours of the 15th.
The Geminids are pieces of debris from an asteroid called 3200 Phaethon. Earth runs into Phaethon’s debris stream every year in mid-December, causing meteors to fly from the direction of the constellation Gemini – hence the name “Geminids.”
Under dark, clear skies, the Geminids can produce up to 120 meteors per hour. But this year, a bright, nearly full moon will hinder observations of the shower. Observers can hope to see up to 30 meteors per hour.
HOW CAN YOU SEE THE GEMINIDS?
Weather permitting, the Geminids can best be viewed from around midnight to 4 a.m. local time. The best time to see them is around 2 a.m. your local time on December 14. This time is when the Geminid radiant is highest in your night sky. The radiant is the celestial point in the sky from which the paths of meteors appear to originate.
The higher the radiant rises into the sky, the more meteors you are likely to see.
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 disrupt your night vision. Lie flat on your back and look straight up, taking in as much sky as possible. You should soon start to see Geminid meteors!
As the night progresses, the Geminid rate will increase. If you see a meteor, try to trace it backwards. If you end up in the constellation Gemini, there is a good chance you’ve seen a Geminid. The Geminids are best observed in the Northern Hemisphere, but no matter where you are in the world (except Antarctica), some Geminids will be visible.
By: Bill Cooke
Lead, NASA Meteoroid Environment Office
The media is currently broadcasting the prediction of an outburst of the alpha Monocerotid meteor shower on the night of November 21. The researchers making the prediction, Dr. Peter Jenniskens and Esko Lyytinen, have made calculations that indicate that there may be zenithal hourly rates as high as 400 to 1000 meteors per hour around 11:50 PM Eastern Standard Time (10:50 PM Central and 9:50 PM Mountain; you will note that I am not giving a Pacific time – more on that later). These are impressive numbers, generating lots of buzz in the media. I love meteor outbursts and storms, so I was initially quite excited – I mean, what’s there not to like about an impromptu display involving lots of meteors from a yet-to-be discovered comet?
But as the media inquiries increased, I began to wonder if all the attention is justified. Being a meteor shower forecaster, I am all too aware of the fact that such predictions (including mine), while pretty accurate on the timing, often estimate a shower intensity higher (factors of a few) than what actually takes place. So I decided to take a more detailed look, starting with some dumpster diving for old papers about this shower and making a few calculations of my own. That’s when the skepticism kicked in – I now think there is a pretty good chance there may be no outburst at all. And even if there is, it won’t be as impressive as many think. Allow me to share…
In Dr. Jenniskens and Lyytinen’s work, the Earth is forced to pass through the center of alpha Monocerotid meteor stream (AMOs for short) during the shower’s 1925 and 1935 outbursts. We have no idea if this actually happened, but it is a reasonable assumption if these outbursts were more intense than the last one in 1995. Based on this, they conclude that the AMOs are produced by a long period comet that takes about 500 years to orbit the Sun. IF this is right, then we should pass very close to the center of the meteor stream this year, missing it by a scant 15,000 miles. That’s just a tad closer than we got back in 1995, when the observed zenithal hourly rate was about 400 per hour. And it’s why the forecast rate is so high – closer means the same intensity or better.
However, the intensity of the outburst is very dependent on the size of the parent comet’s orbit. If it is much smaller, or larger, the distance from the stream center will be bigger, and there will not be any sky show, just the normal AMOs, puttering along with their normal rate of 3 or so meteors per hour. And since we have not yet discovered this mysterious parent comet, who knows how close the estimate of the orbit is to the actual? A good reason to step outside Thursday night, because the cool thing is that if an outburst does occur, we will have a pretty good idea of the orbit of this comet – not from observing the comet with telescopes, but by counting its debris as they burn up in our atmosphere.
The old papers I dug up also proved enlightening. I could find no meteor rate numbers for the 1925 outburst – just that it was short, with a fair number of meteors. The 1935 AMO outburst was observed in 2 places – a meteor observer in Begumpet, India and the commanding officer of a U.S. ship in the Philippines each reported seeing a total of just over 100 meteors in a 40 minute span of time. That’s nice, but it certainly is nowhere close to the spectacular rates produced by the Leonid and Draconid meteor storms of the 1900’s. A moderate outburst, yes, but not a meteor storm. Even fewer were seen in 1985, when one observer reported 36 meteors seen over 16 minutes of time. It is true that the calculated rates were in the hundreds per hour, but what matters to the average person is the total number of meteors they will see. Zenithal hourly rates give the theoretical rates for a perfect observer under perfect skies with the shower radiant straight overhead (something that never happens in reality), and while they may be a good way to scientifically measure meteor shower activity, they are poor indicators of what will actually be seen. The observer reports, however, do tell us what we might expect.
And then we come to 1995, the best-observed AMO outburst. Quite a few observers in Western Europe saw about 100 meteors over an hour’s time, consistent with the observations of the previous AMO outbursts. These data do not indicate that we were closer to the AMO stream center in 1925 and 1935, as Jenniskens and Lyytinen suggest; in fact, it appears that AMO outbursts are fairly constant with regard to numbers, with about 100 meteors seen over the less-than-an-hour duration of the outburst. At face value, this would mean no outburst. However, the numbers seeming to be not strongly dependent on distance is possibly good news; even if the researchers’ distance assumptions are wrong, we still may have a chance of a respectable, albeit short, outburst, provided Earth gets “close enough” to the stream center.
At the beginning of this post, I gave times for the predicted peak in the Eastern, Central, and Mountain time zones, but left out Pacific. That’s because the AMO radiant – the point in the constellation of Monocerotis from which the meteors appear to originate – is below the horizon at the peak time for locations west of Denver. That means people on the Pacific Coast will not see this outburst, even if their skies are clear. So if you live there and want to experience the shower, you need to go quite a bit east. If you do, please don’t blame me if the outburst is a no show; as I said, I am a bit skeptical. For the eastern United States, the radiant is not very high in the sky at the forecast peak time (about 23° in Orlando), which is unfortunate since the observed number of meteors is tied to the radiant altitude. The higher the radiant, the more meteors people see. So my computer savvy colleagues have generated this map, which shows the total numbers of meteors you can expect to see if the outburst is similar to that of 1995. Blue is good, red is worse, white means no meteors at all. The decrease in total expected meteors is pretty obvious as you move west
And of course, there is the weather. Remember, you need clear, dark skies to see meteors, and it looks like Mother Nature is going to be mean, with clouds forecast over much of the part of the U.S. that has a chance of observing the outburst. So, if you are gifted with good seeing, give yourself about 45 minutes to adjust to the dark – go out about 10:35 PM Eastern, 9:35 PM Central, or 8:35 PM Mountain. Lie flat on your back, look straight up, and enjoy looking at the night sky (maybe listen to some appropriate tunes, but don’t look at your cell phone, as the bright screen will ruin your night vision). If Jenniskens and Lyytinen are right, you might see some pieces of a comet that awaits discovery, burning up in the atmosphere 60 miles above your head.
That’s worth a couple of hours, I think. Even if there is no outburst, it doesn’t hurt to get out under the stars for a bit.
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!
Did you know there is a night set aside each year to observe Earth’s closest celestial neighbor, the Moon? International Observe the Moon Night has been held annually since 2010 and is a worldwide celebration of the Moon and lunar science. Each year, the celebration is held in September or October when the Moon is in the first quarter because it is visible in the afternoon and early evening hours when most events are held.
If you live in or near Huntsville, Alabama, you can join our local celebration Saturday, Oct. 20, from 5:30-8:30 p.m. CDT at the U.S. Space & Rocket Center’s Davidson Center. The event is hosted by NASA’s Marshall Space Flight Center’s Planetary Missions Program. Members of the public are encouraged to attend and it is free. The event will include lunar and solar system exploration exhibits and a variety of hands-on activities for children and adults. Don’t live in Huntsville? No worries! There are events held worldwide and you can find a list of them here.
As you are gearing up for your own International Observe the Moon Night celebration, check out these fun facts about the Moon.
The Moon is Earth’s satellite and orbits the Earth at a distance of about 384,000 km or 239,000 miles.
The Moon makes a complete orbit around the Earth in 27 Earth days. The Moon keeps the same side or face, towards the Earth during its orbit.
More than 100 spacecraft have been launched to explore the Moon. It is the only celestial body beyond Earth visited by human beings.
Astronauts brought back a total of 842 pounds of lunar rocks and soil to Earth.
The 50th anniversary of the Apollo 11 landing on the Moon will be next summer on July 20, 1969. Neil Armstrong was the first human to set foot on the Moon, followed by Buzz Aldrin.
Can’t get to an event this weekend? You can still go outside no matter where you live and look at our incredible neighbor. For a list of Moon phases and other cool Moon facts, check out the NASA Science Earth’s Moon page.