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.
The sky will put on a show Nov. 11 when Mercury journeys across the Sun. The event, known as a transit, occurs when Mercury passes directly between Earth and the Sun. From our perspective on Earth, Mercury will look like a tiny black dot gliding across the Sun’s face. This only happens about 13 times a century, so it’s a rare event that skywatchers won’t want to miss! Mercury’s last transit was in 2016. The next won’t happen again until 2032!
“Viewing transits and eclipses provide opportunities to engage the public, to encourage one and all to experience the wonders of the universe and to appreciate how precisely science and mathematics can predict celestial events,” said Mitzi Adams, a solar scientist in the Heliophysics and Planetary Science Branch at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “Of course, safely viewing the Sun is one of my favorite things to do.”
This year’s transit will be widely visible from most of Earth, including the Americas, the Atlantic and Pacific Oceans, New Zealand, Europe, Africa, and western Asia. It starts at about 6:35 a.m. CST, but viewers in some areas, such as the West Coast, will have to wait until the Sun rises at their location to see the transit already in progress. Thankfully, this transit will last almost six hours, so there will be plenty of time to catch the show. At about 9:20 a.m. CST, Mercury’s center will be as close as it is going to get to the Sun’s.
Mercury’s tiny disk, jet black and perfectly round, covers a tiny fraction of the Sun’s blinding surface — only 1/283 of the Sun’s apparent diameter. So you’ll need the magnification of a telescope (minimum of 50x) with a solar filter to view the transit. Never look at the Sun directly or through a telescope without proper protection. It can lead to serious and permanent vision damage. Always use a safe Sun filter to protect your eyes!
Scientists have been using transits for hundreds of years to study the way planets and stars move in space. Edmund Halley used a transit of Venus in 1761 and 1769 to determine the absolute distance to the Sun. Another use of transits is the dimming of Sun or star light as a planet crosses in front of it. This technique is one way planets circling other stars can be found. Scientists can measure brightness dips from these other stars (or from the Sun) to calculate sizes of planets, how far away the planets are from their stars, and even get hints of what they’re made of.
As we head into the darker half of the year here in Earth’s Northern Hemisphere, astronomers at NASA’s Meteoroid Environment Office are sharing eerie images from their meteor cameras. The specialized cameras are part of a network set up by the meteor team to observe and study fireballs — meteors brighter that the planet Venus. Here’s a look at the some of the birds, bugs and stranger things that have crept from the shadows into their view.
Images and video of fireballs from the cameras are available for anyone to download from NASA’s All-Sky Fireball Network. For a complete album of our favorite eerie images from the cameras, visit Marshall’s Flickr gallery.
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 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.
35.8 million miles is definitely not what most of us would consider “close.” But in planetary terms, close is definitely relative! On July 31, Mars will be 35.8 million miles from Earth, which is the closest it has been to Earth in 15 years. What does this mean for sky watchers? It means the Red Planet will appear super bright, and with its orange-red color, will be hard to miss in the nighttime sky. From July 27-30, the point in Mars’ orbit will come closest to Earth, and will be closest to Earth before sunrise Eastern Time on July 31.
What defines a “close approach?” The minimum distance from the Earth to Mars is about 33.9 million miles and does not happen very often. Because Earth and Mars have elliptical orbits and are slightly tilted to each other, all close approaches are not equal. When Mars slowly approaches what astronomers call opposition, it and the Sun are on opposite sides of the Earth. Earth and Mars align in opposition about every two years (fun fact: this is why most NASA missions to the Red Planet are at least two years apart – to take advantage of the closer distance). Opposition to Mars is at its closest to the Sun every 15 to 17 years, when excellent views of the Red Planet from Earth can occur. This is what is happening on the early morning hours of July 31.
Is 35.8 million miles the closest Mars has ever been to Earth? Nope. In 2003, Mars was 34.6 million miles from Earth and the closest it had been in nearly 60,000 years. This type of proximity won’t occur again until 2287. But, there will be another close approach in October 2020 when the distance between the Red Planet and Earth will be 38.6 million miles.
Now that we’ve gotten all of that out of the way, what does this mean for you, the novice astronomer or general sky-watcher? It means that if you have clear skies where you live, go outside on the overnight hours of July 30 or early morning hours of July 31 and look up. The planet will be brighter than usual and will have an orange or red haze. You can also look through a telescope. If weather is bad where you are, NASA will be streaming live from the Griffith Observatory.
Last August, citizens and visitors to the United States of America had a rare opportunity to see a total solar eclipse, because the path of totality ranged from Oregon to South Carolina, essentially bisecting the country. But alas, the total lunar eclipse happening on Friday, July 27, will totally miss the United States. Being able to observe the Moon totally immersed in Earth’s shadow depends mostly on whether it is dark at the time the eclipse happens, so about half the Earth would be in the right place to see the eclipse, weather permitting of course. This time, residents of Europe, Africa, Asia, Australia, and parts of South America will be so lucky. In contrast, totality for a solar eclipse is very narrow and only a very small portion of Earth is in the shadow of the Moon. For the August 2017 eclipse, only those within an approximately 100 km (63 miles) wide path saw the Sun totally eclipsed.
So what happens when there is a lunar eclipse? Unlike the solar variety, Earth blocks the Sun for a lunar eclipse. For the lunar eclipse to happen, the Moon’s phase must be “full”, which means that the orbiting Moon is opposite the Sun, with Earth in between. When the Sun sets in the west, the Moon rises in the east — and this event happens once a “moonth” (or month). But a lunar eclipse does not happen every month. Why is that?
Well, now we get into more tricky territory. Let’s try a thought experiment. Draw a line between the centers of the Sun, Earth, and Moon. This line is part of a plane that describes how Earth orbits the Sun, called the plane of the ecliptic. The Moon orbits Earth, only its orbit is tilted with respect to the plane of the ecliptic, sometimes the Moon is above the plane, sometimes it is below the plane. Only when the Moon’s orbit lines up with the ecliptic plane do we have a chance for an eclipse. If the phase of the Moon is “full” when this happens, we have a lunar eclipse. If the phase of the Moon is “new,” we have a solar eclipse. Sometimes the orbital planes do not line up exactly, in those cases, we would have partial eclipses.
The July 27 eclipse is somewhat special because the length of totality will be the longest of this century at one hour, 43 minutes. Why? Several reasons. The Moon will be at apogee, or at the farthest distance from Earth (406,000 km or 252,000 mi) possible for our Moon. Objects in orbit around Earth move slower the farther away they are, which means it will take longer for the Moon to traverse the width of Earth’s shadow. In addition, the Moon will be almost exactly on that line that connects Sun, Earth, Moon, also increasing the length of time the Moon will spend in the umbral (darkest) part of Earth’s shadow. Finally, Earth reached its greatest distance from the Sun (aphelion) quite recently (July 6), meaning that Earth’s shadow on July 27 will be close to the largest it can be, adding even more distance (and time) to the Moon’s shadowy traverse.
The partial phase of the eclipse will begin at 18:24 UT, with totality beginning at 19:30 UT (see the NASA time zone page for help with conversion to your local time and official U.S. time). Totality will be over at 21:13 UT and the partial phase ends at 22:19 UT. Viewing a lunar eclipse does not require a telescope or even special glasses; however, while waiting for totality to begin, which is marked by a reddish-brown color to the Moon, a telescope could be used to view two planets that are in the evening sky. Mars will be visible, and should be pretty bright since there is currently a dust storm covering the entire planet. So the telescope will not see any surface detail here, but the redness of the planet will contrast well with the reddish hue of a totally eclipsed Moon. Saturn will be visible to the west of Mars — and even binoculars will resolve the rings, but a telescope could provide more detail. For all observers, find the full Moon in the night sky, Mars will be close to and below (south of) the Moon, a bright reddish “star-like” object. For detailed information about this eclipse, click here.