Watch a House-Sized Asteroid Pass Close to Earth Tonight (October 11/12)

On Oct. 12, a house-size asteroid will pass quite close to Earth – only 26,000 miles (42,000 kilometers) away. This is just above the orbital altitude of communications satellites and a little over one-tenth the distance to the Moon. But not to fear, it has no chance of hitting Earth.

Artists concept of Asteroid 2012 TC4’s close pass of Earth on Oct. 12, 2017. Based on continuing observations, scientists have determined that it will pass the Earth at a distance of about 26,000 miles (42,000 kilometers). Credits: NASA/JPL-Caltech

Asteroid 2012 TC4 was discovered almost 4 years ago to the day, on October 4, 2012, just a week before it made another close pass by Earth.

With a little more advance notice this time around, NASA and asteroid trackers around the world are using the close pass to test their ability to operate as a coordinated International Asteroid Warning Network. This is a growing global observing network to communicate and coordinate their optical and radar observations in a real scenario.

“Asteroid trackers are using this flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid-impact threat,” said Michael Kelley, program scientist and NASA lead for the TC4 observation campaign. You can read more details about the observing campaign in our previous article.

You can watch it pass by too, if you have a at least an 8 inch telescope, according to our David Dickinson, who has a very informative post about 2012 TC4 at Sky & Telescope.

Closest approach will be at on October 12, 2017, at 5:41 Universal Time (1:41 a.m. EDT).

You can also watch a couple of webcasts of the pass:

Virtual Telescope will have a live feed, and the Slooh Telescope crew will also host a live feed starting tonight at 8 pm EDT on Oct. 11.

2012 TC4 is estimated to be 45 to 100 feet (15 to 30 meters) in size.

NASA’s Asteroid Watch says that no asteroid currently known is predicted to impact Earth for at least the next 100 years.

More info at NASA’s website.

Astronomy Cast Ep. 452: Summer Observing Challenges

Summer is almost here, and for the northern hemisphere, that means warm nights for observing. But what to observe? We’re here with a list of events and targets for you to enjoy over the summer. Get your calendars handy, and start organizing some events with your friends, and then get out there!

Visit the Astronomy Cast Page to subscribe to the audio podcast!

We usually record Astronomy Cast as a live Google+ Hangout on Air every Friday at 1:30 pm Pacific / 4:30 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.

Mars At Closest Point To Earth in 11 Years May 30, 2016

Mars in all its red-hued glory. Image: NASA, ESA, the Hubble Heritage Team (STScI/AURA), J. Bell (ASU), and M. Wolff (Space Science Institute)

If you have a telescope, (What?! You don’t have one?) you’re in for a visual treat tonight. Mars will be at its closest point to Earth in 11 years on May 30. This event is worth checking out, whether with a telescope, astronomy binoculars, or online.

While today is when Mars is at its closest, you actually have a couple weeks to check this out, as the distance between Mars and Earth gradually becomes greater and greater. Today, Mars is 76 million kilometers (47.2 million miles) away, but up until June 12th it will still be no further than 77 million kilometers (48 million miles) away.

The furthest Mars can be from Earth is 401 million kilometers (249 million miles), when the two planets are on the opposite side of the Sun from each other.

For most of us with backyard ‘scopes, it’s difficult to make out much detail. You can see Mars, and at the most you can make out a polar cap. But it’s still fascinating knowing you’re looking at another planet, one that was totally unknowable for most humans who preceded us. A planet that we have rovers on, and that we have several craft in orbit around.

If you don’t have a scope, have no fear. There will be a flood of great astro-photos of Mars in the next few days. There are also options for live streaming feeds from powerful Earth-based telescopes.

The last time Mars was this close to Earth was 2005. A couple years before, the distance shrank to 55.7 million km (34.6 million miles.) That was the closest Mars and Earth have been in several thousand years. In 2018, the two planets will be nearly that close again.

This event is often called “opposition”, but it’s actually more correctly called “closest approach.” Opposition occurs a couple weeks before closest approach, when Mars is directly opposite the Sun.

A top-down image of the orbits of Earth and Mars. Image: NASA
A top-down image of the orbits of Earth and Mars. Image: NASA

But whether you call it opposition, or closest approach, the event itself is significant for more than just looking at it. Missions to Mars are planned when the two planets are close to each other. This reduces mission times drastically.

Mars Express, the mission being conducted by the European Space Agency (ESA) was launched in 2003, when the two planets were as close to each other as they’ve been in thousands of years. All missions to Mars can’t be so lucky, but they all strive to take advantage of the orbital cycles of the two planets, by nailing launch dates that work in our favour.

As for finding Mars in the night sky, it’s not that difficult. If you have clear skies where you are, Mars will appear as a bright, fire-yellow star.
“Just look southeast after the end of twilight, and you can’t miss it,” says Alan MacRobert, a senior editor of Sky & Telescope magazine, in a statement. “Mars looks almost scary now, compared to how it normally looks in the sky.”

This image shows how Mars appears at different times of the year in a typical backyard telescope. Image: NASA/JPL-Caltech
This image shows how Mars appears at different times of the year in a typical backyard telescope. Image: NASA/JPL-Caltech

Although Mars is the closest thing in the sky to Earth right now, other than the Moon, it isn’t the brightest thing in the night sky. That honour is reserved for Jupiter, even though it’s ten times further away. Jupiter is twenty times larger in diameter than Mars, so it reflects much more sunlight and appears much brighter. (Obviously, everything in the night sky pales in comparison to the Moon.)

The reason for such a variation in distances between the planets lies in their elliptical orbits around the Sun. There’s a great video showing how their orbits change the distance between the two planets, here.

If you don’t have a telescope, you can still check Mars out. Go to slooh.com to check out live feeds from a proper telescope.

Space Station Back At Dusk / See Orion’s Curlicue and Five Dawn Planets

I hadn’t been paying attention, so I was pleasantly surprised two nights ago to see the International Space Station (ISS) made a bright pass in the southwestern sky. A quick check revealed that another round of evening passes had begun for locations across the central and northern U.S., Canada and Europe.  I like the evening ones because they’re so much convenient to view than those that occur at dawn. You can find out when the space station passes over your house at NASA’s Spot the Station site or Heavens Above.

The six-member Expedition 46 crew are wrapping up their work week on different types of research including botany, bone loss and pilot testing. Plants are being grown on the International Space Station so future crews can learn to become self-sustainable as they go farther out in space. While they work their jobs speeding at more than 17,000 mph overhead, we carry on here on the surface of the blue planet.

Edgar Mitchell stands by the U.S. flag he and fellow astronaut Alan Shepard planted on the Fra Mauro region of the moon back in February 1971. Credit: NASA
Edgar Mitchell stands by the U.S. flag he and fellow astronaut Alan Shepard planted on the Fra Mauro region of the moon back in February 1971. Credit: NASA

U.S. astronaut Scott Kelly regularly tweets photos from the station and recently noted the passing of Apollo 14 astronaut Edgar Mitchell, who died Thursday at age 85 on the eve of the 45th anniversary of his lunar landing on February 5, 1971. Mitchell was one of only 12 people to walk on the moon and described the experience to the UK Telegraph in 2014:


Relive the Mitchell’s Apollo 14 mission to the moon in 9 minutes and 57 seconds

“Looking at Earth from space and seeing it was a planet in isolation … that was an experience of ecstasy, realizing that every molecule in our bodies is a system of matter created from a star hanging in space. The experience I had was called Samadhi in the ancient Sanskrit, a feeling of overwhelming joy at seeing the Earth from that perspective.”

A pair of binoculars will make the "Curlicue" pop in Orion's Belt. Although the stars aren't related, they form a delightfully curvy line-of-sight pattern. Credit: Bob King
A pair of binoculars will make the “Curlicue” pop in Orion’s Belt. Although the stars aren’t related, they form a delightfully curvy line-of-sight pattern. Credit: Bob King

Only a human could stand in so barren and forbidding a place and experience such profound joy. You don’t have to go to the moon to be moved by sights in the night. Just step outside and watch the ISS glide by or grab a pair of binoculars and aim them at Orion’s Belt. Orion stands due south around 8 o’clock in in mid-February practically shouting to be looked at.

A pair of binoculars will make the "Curlicue" pop in Orion's Belt. Although the stars aren't related, they form a delightfully curvy line-of-sight pattern. Credit: Bob King
This wider view shows the Belt, Curlicue and the Orion Nebula just to the south — all excellent objects for binocular study. Stellarium

The Belt is lovely enough, but its surroundings glitter with stars just below the naked eye limit, in particular a little curlicue or “S” between Alnilam and Mintaka composed of 6th and 7th magnitude stars. Look for it in any pair of binoculars and don’t stop there. Take a few minutes to sweep the area and enjoy the starry goodness about then drop a field of view south for a look at the Orion Nebula. Inside this fuzzy spot 10 light years across and 1,350 light years away, hundreds of new stars are incubating, waiting for the day they can blaze forth like their compadres that make up the rest of Orion.

A thin crescent moon visited Venus and fainter Mercury this morning Feb. 6th at dawn over Rome, Italy. Credit: Gianluca Masi
A thin crescent moon visited Venus and fainter Mercury this morning Feb. 6th at dawn over Rome, Italy. Credit: Gianluca Masi

After touting the advantages of evening sky watching, forgive me if I also direct you to the morning sky and potential sleep loss. Although the waning crescent moon has now departed the scene, the wonderful alignment of Mercury, Venus, Saturn, Mars and Jupiter remains visible in the coming week even as Mercury slowly sinks back toward the eastern horizon. If you haven’t seen this “gang of 5”, set your alarm for a look starting about an hour before sunrise.

This map shows the entire southern sky around 45 minutes to an hour before sunrise Sunday morning Feb. 7. The ecliptic is the plane of Earth's orbit projected into space and the "highway" taken by the sun, Moon and planets as they orbit the sun. Although Mercury is lowest, it's only about 4.5 degrees from Venus and easy to find. Stellarium
This map shows the entire southern sky around 45 minutes to an hour before sunrise Sunday morning Feb. 7. The ecliptic is the plane of Earth’s orbit projected into space and the “highway” taken by the sun, Moon and planets as they orbit the sun. Although Mercury is lowest, it’s only about 4.5 degrees from Venus and easy to find. Stellarium

Find a location with as wide open a view as possible of the southeastern horizon. Jupiter, Mars and Saturn are plenty high up at that time and easy to spot, but Venus and Mercury hover only 5°-10° high. Both will pose no problem if you can get the trees and buildings out of the way! By the end of the coming week, Mercury will become challenging and then slip away.

Clear skies!

Gallery: 2015 Perseids Are Putting on a Show

Have you been looking up the past few nights, trying to see the Perseid Meteor Shower? Many of our readers have been turning their eyes — and cameras — to the skies, with spectacular results. This year’s Perseids were predicted to be one of the best ever, since there has been little to no moonlight to upstage the shower. As you can see from the images here, many astrophotographers were able to capture fast and bright meteors, and even some that left persistent trains.

Remember, tonight (Wednesday, August 12, 2015) is projected to be the peak, so if you’ve got clear skies, take advantage of this opportunity to see a great meteor shower. You can find out how and when to see them in our previous detailed articles by our in-house observing experts David Dickinson and Bob King.

And enjoy the view from our readers in this gallery of 2015 Perseids:

A Perseid Meteor, the Milky Way and the photographer on August 11, 2015 near Bamburgh, Northumberland, England. Credit and copyright:  Peter Greig.
A Perseid Meteor, the Milky Way and the photographer on August 11, 2015 near Bamburgh, Northumberland, England. Credit and copyright:
Peter Greig.
An 'exploding' Perseid meteor as seen on August 11, 2015. Credit and copyright: Chris Lyons.
An ‘exploding’ Perseid meteor as seen on August 11, 2015. Credit and copyright: Chris Lyons.
Bright Perseid and Perseus. Credit and copyright: Chris Lyons.
Bright Perseid and Perseus. Credit and copyright: Chris Lyons.
A green Perseid meteor, along with 2 satellites show up in this image taken on August 11, 2015. Credit and copyright: eos-001 on Flickr.
A green Perseid meteor, along with 2 satellites show up in this image taken on August 11, 2015. Credit and copyright: eos-001 on Flickr.
Perseid meteor from early morning, August 12, 2015 in Weatherly, Pennsylvania. Taken with a Canon 6D and Samyang 14mm lens, 40 second exposure at ISO 3200, unguided. Credit and copyright: Tom Wildoner.
Perseid meteor from early morning, August 12, 2015 in Weatherly, Pennsylvania. Taken with a Canon 6D and Samyang 14mm lens, 40 second exposure at ISO 3200, unguided. Credit and copyright: Tom Wildoner.
Perseid Meteor near Cassiopeia along with the Andromeda Galaxy, as seen from France on August 10, 2015. Credit and copyright: VegaStar Carpentier/ VegaStar Carpentier Photography.
Perseid Meteor near Cassiopeia along with the Andromeda Galaxy, as seen from France on August 10, 2015. Credit and copyright: VegaStar Carpentier/ VegaStar Carpentier Photography.
A Perseid Meteor as seen on August 8, 2015, taken from Oxfordshire with a Canon 1100D + 18-55mm lens, ISO-1600 for 30 seconds. Credit and copyright: Mary Spicer.
A Perseid Meteor as seen on August 8, 2015, taken from Oxfordshire with a Canon 1100D + 18-55mm lens, ISO-1600 for 30 seconds. Credit and copyright: Mary Spicer.

Prolific night sky photographer John Chumack near Dayton, Ohio put together this video of 81 Perseid meteors he captured on August 12, 2015 with his Automated low light -Meteor Video Camera Network:

If you are clouded out, you can still enjoy the shower. NASA TV will be tracking the Perseids live on Wednesday, August 12 starting at 10PM EDT/02:00 UT:

If You Can Find Orion, You Can Find Comet Lovejoy

Comet Lovejoy (2014 Q2) is now visible in the night sky, and while you’ll need binoculars or a low-power telescope to see it best, the perfect window of opportunity to see it for yourself is starting now! We’ve heard from some readers that they’ve had some trouble spying it, but photographer Brian Moran has snapped the perfect picture to show you EXACTLY where to look for the comet. All you need to do is look for the easy-to-find constellation of Orion, and swing your eyes to the right (about 20 degrees) and up slightly up.

Brian said he was having trouble finding Lovejoy, but perhaps it may have been because he was looking a little too close to Orion. “Orion is a great frame of reference, but all of the photos I saw online made it seem like it was closer to Orion than it actually is,” he said.

Comet Q2 Lovejoy is currently shining at 4th magnitude, and if you’ve got a really dark sky, you may be able to see it with the unaided eye. as our David Dickinson explained, this comet is now entering “prime time” evening sky viewing, as it is visible over the southern horizon at around 9:30 PM local time this weekend, then 8:00 PM on January the 15th, and just before 6:00 PM by January 31st.

Tonight (Thursday, January 8) we’ll have a “two-hour window of darkness between the end of twilight and moonrise for those of us in the world’s mid-northern latitudes. Each night after tonight the Moon rises nearly an hour later,” said Sky & Telescope’s Alan MacRobert.

Finder chart for Comet Lovejoy, C/2014 Q2, during January 2015. The dates are in Universal Time; the ticks are at 0:00 UT (7:00 p.m. on the previous date Eastern Standard Time). Click on the image for larger, print-friendly black-on-white PDF, courtesy of Sky & Telescope.
Finder chart for Comet Lovejoy, C/2014 Q2, during January 2015. The dates are in Universal Time; the ticks are at 0:00 UT (7:00 p.m. on the previous date Eastern Standard Time). Click on the image for larger, print-friendly black-on-white PDF, courtesy of Sky & Telescope.

While C/Q2 Lovejoy passed closest to Earth yesterday (January 7) at a distance of 0.47 a.u. (44 million miles; 70 million km), the comet should remain at about the same brightness as it crosses the sky into Taurus, Aries, and Triangulum, higher and higher in early evening. It will pass 8° west-southwest of the Pleiades on the evening of January 17th.

MacRobert also explained that although the comet is beginning to recede from us, its intrinsic brightness should still be increasing a bit. “That’s because it doesn’t reach perihelion (its closest to the Sun) until January 30th (at a rather distant 1.29 a.u. from the Sun),” he said. “By that date the comet should finally be fading slightly from Earth’s point of view. And in late January the Moon returns; it’s first-quarter on the 26th.”

Here are some great images of Comet Lovejoy taken by Universe Today readers. Be sure to check out our Flickr group for more great images! We have nearly 1,500 members and new photos are added every day. And if you take an astrophoto, join our group and submit your photos! We may use your image in an upcoming article!

A wide-angle shot of Comet Lovejoy 2014 Q2 above snow-covered trees. Taken as it neared Orion on January 6, 2014.  Credit and copyright: Marion Haligowski.
A wide-angle shot of Comet Lovejoy 2014 Q2 above snow-covered trees. Taken as it neared Orion on January 6, 2014. Credit and copyright: Marion Haligowski.
C/2014 Q2 Lovejoy on 7th January 2015. A couple of satellites managed to sneak in the image, too! Credit and copyright: JP Willinghan.
C/2014 Q2 Lovejoy on 7th January 2015. A couple of satellites managed to sneak in the image, too! Credit and copyright: JP Willinghan.
Comet C/2014 Q2 Lovejoy Passes Messier 79 Narrowfield C False Color, taken on Dec 29, 2014, from New Mexico Skies using a 43-cm CDK telescope and STXL-6303 camera on a PME II mount. Credit and copyright: Joseph Brimacombe.
Comet C/2014 Q2 Lovejoy Passes Messier 79 Narrowfield C False Color, taken on Dec 29, 2014, from New Mexico Skies using a 43-cm CDK telescope and STXL-6303 camera on a PME II mount. Credit and copyright: Joseph Brimacombe.
A monochrome image of Comet Lovejoy (2014 Q2) taken on December 31, 2014. Credit and copyright: Damian Peach.
A monochrome image of Comet Lovejoy (2014 Q2) taken on December 31, 2014. Credit and copyright: Damian Peach.
Comet Lovejoy, as seen on December 29, 2014 at around 12.30AM SGT from Singapore. Also visible is spiral galaxy NGC1886, seen to the left of the coma. Total exposure time is 12 minutes. Credit and copyright: Justin Ng.
Comet Lovejoy, as seen on December 29, 2014 at around 12.30AM SGT from Singapore. Also visible is spiral galaxy NGC1886, seen to the left of the coma. Total exposure time is 12 minutes. Credit and copyright: Justin Ng.
Comet Lovejoy as seen from Aldalucia, Spain on December 30, 2013. Credit and copyright: Ian Sharp.
Comet Lovejoy as seen from Aldalucia, Spain on December 30, 2013. Credit and copyright: Ian Sharp.
Comet Lovejoy Passing Globular Cluster M-79. Credit and copyright: Greg Redfern.
Comet Lovejoy Passing Globular Cluster M-79. Credit and copyright: Greg Redfern.
A two-part panorama of Comet 2014 Q2 Lovejoy as seen from Payson, Arizona on December 27, 2014. Credit and copyright: Chris Schur
A two-part panorama of Comet 2014 Q2 Lovejoy as seen from Payson, Arizona on December 27, 2014. Credit and copyright: Chris Schur

Perigee “Super” Moon Images from Around the World

Wow! The astrophotographers out there are getting artsy! Take a look at some of the most artistic images of the full Moon we’ve seen yet.

The August 10 full Moon was a so-called “super” Moon — and it was the “super-est” of a trio of full Moons being at perigee, or its closest approach to the Earth in its orbit. It was just 356,896 kilometers distant at 17:44 UTC, less than an hour from Full. You can see a comparison shot of the perigee and apogee Moons this year immediately below. Find all the technical details here, but enjoy a gallery of great images from around the world

A comparison the between two 'extreme' full Moons of 2014:  the perigee Full Moon of August 10th, and the apogee full Moon of January 16. As seen from Central Italy. Credit and copyright: Giuseppe Petricca.
A comparison the between two ‘extreme’ full Moons of 2014: the perigee Full Moon of August 10th, and the apogee full Moon of January 16. As seen from Central Italy. Credit and copyright: Giuseppe Petricca.
The August 10, 2014 'super' Moon. Credit and copyright: Robbie Ambrose.
The August 10, 2014 ‘super’ Moon. Credit and copyright: Robbie Ambrose.
Supermoon timelapse composite on August 10 near the ship mast at Barnegat Light on Long Beach Island, New Jersey. Credit and copyright: FrankM301 on Flickr.
Supermoon timelapse composite on August 10 near the ship mast at Barnegat Light on Long Beach Island, New Jersey. Credit and copyright: FrankM301 on Flickr.

A cloudy look at the perigee Moon of August 10, 2014 along side the Desde el Obelisco, Malecón de Santo Domingo, Dominican Republic. Credit and copyright: Goku Abreu.
A cloudy look at the perigee Moon of August 10, 2014 along side the Desde el Obelisco, Malecón de Santo Domingo, Dominican Republic. Credit and copyright: Goku Abreu.

'Super' Moon, August 10, 2014, taken with Nikon D80 from Ottawa, Canada. Credit and copyright: Andrew Symes.
‘Super’ Moon, August 10, 2014, taken with Nikon D80 from Ottawa, Canada. Credit and copyright: Andrew Symes.

Super Moon (and a companion) rising over Brixton, South London. 10/08/2014. Credit and copyright: Owen Llewellyn.
Super Moon (and a companion) rising over Brixton, South London. 10/08/2014. Credit and copyright: Owen Llewellyn.
Camaro and Full Moon - Aug 9, 2014. Taken from the Cairns Wharf in Australia at dusk using an iPhone 5. Three frames; two exposures each. Credit and copyright: Joseph Brimacombe.
Camaro and Full Moon – Aug 9, 2014.Taken from the Cairns Wharf in Australia at dusk using an iPhone 5. Three frames; two exposures each. Credit and copyright: Joseph Brimacombe.

It was prom night in Cairns… so the fancy cars were out. See Joseph’s other “prom supermoon” image here.

People watch the nearly 'super' Moon rise on August 9, 2014 near a lighthouse.  Credit and copyright:  Will Nourse.
People watch the nearly ‘super’ Moon rise on August 9, 2014 near a lighthouse. Credit and copyright: Will Nourse.
Perigee Full Moon mosaic from August 10, 2014 (a first attempt at a mosaic!) Credit and copyright: Mary Spicer.
Perigee Full Moon mosaic from August 10, 2014 (a first attempt at a mosaic!) Credit and copyright: Mary Spicer.
Perigee Moon rise over London on August 10, 2014. Credit and copyright: Sculptor Lil.
Perigee Moon rise over London on August 10, 2014. Credit and copyright: Sculptor Lil.
The perigee Moon from Toronto, Canada at 8:35 pm EDT. Credit and copyright: Rick Ellis.
The perigee Moon from Toronto, Canada at 8:35 pm EDT. Credit and copyright: Rick Ellis.
A full Moon flyby, as seen from Paris, France. Credit and copyright: Sebastien Lebrigand.
A full Moon flyby, as seen from Paris, France. Credit and copyright: Sebastien Lebrigand.

Even NASA got into the “super Moon” astrophoto craze. NASA photographer Bill Ingalls took this beautiful image at The Peace Monument on the grounds of the United States Capitol, in Washington D.C. :

A perigree full moon or supermoon is seen over the The Peace Monument on the grounds of the United States Capitol, Sunday, August 10, 2014, in Washington. A supermoon occurs when the moon’s orbit is closest (perigee) to Earth at the same time it is full. Credit: (NASA/Bill Ingalls)
A perigree full moon or supermoon is seen over the The Peace Monument on the grounds of the United States Capitol, Sunday, August 10, 2014, in Washington. A supermoon occurs when the moon’s orbit is closest (perigee) to Earth at the same time it is full. Credit: (NASA/Bill Ingalls)

Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.

What Is The Great Attractor?

What is at the Center of the Milky Way

There’s a strange place in the sky where everything is attracted. And unfortunately, it’s on the other side of the Milky Way, so we can’t see it. What could be doing all this attracting?

Just where the heck are we going? We’re snuggled in our little Solar System, hurtling through the cosmos at a blindingly fast of 2.2 million kilometers per hour. We’re always orbiting this, and drifting through that, and it’s somewhere out in the region that’s not as horrifically terrifying as what some of our celestial neighbors go through. But where are we going? Just around in a great big circle? Or an ellipse? Which is going around in another circle… and it’s great big circles all the way up?

Not exactly… Our galaxy and other nearby galaxies are being pulled toward a specific region of space. It’s about 150 million light years away, and here is the best part. We’re not exactly sure what it is. We call it the Great Attractor.

Part of the reason the Great Attractor is so mysterious is that it happens to lie in a direction of the sky known as the “Zone of Avoidance”. This is in the general direction of the center of our galaxy, where there is so much gas and dust that we can’t see very far in the visible spectrum. We can see how our galaxy and other nearby galaxies are moving toward the great attractor, so something must be causing things to go in that direction. That means either there must be something massive over there, or it’s due to something even more strange and fantastic.

When evidence of the Great Attractor was first discovered in the 1970s, we had no way to see through the Zone of Avoidance. But while that region blocks much of the visible light from beyond, the gas and dust doesn’t block as much infrared and x-ray light. As x-ray astronomy became more powerful, we could start to see objects within that region. What we found was a large supercluster of galaxies in the area of the Great Attractor, known as the Norma Cluster. It has a mass of about 1,000 trillion Suns. That’s thousands of galaxies.

A March 2013 picture of the Shapley Supercluster from the European Space Agency's Planck observatory. ESA describes it as "the largest cosmic structure in the local Universe." Credit: ESA & Planck Collaboration / Rosat/ Digitised Sky Survey
A March 2013 picture of the Shapley Supercluster from the European Space Agency’s Planck observatory. ESA describes it as “the largest cosmic structure in the local Universe.” Credit: ESA & Planck Collaboration / Rosat/ Digitised Sky Survey

While the Norma Cluster is massive, and local galaxies are moving toward it, it doesn’t explain the full motion of local galaxies. The mass of the Great Attractor isn’t large enough to account for the pull. When we look at an even larger region of galaxies, we find that the local galaxies and the Great Attractor are moving toward something even larger. It’s known as the Shapley Supercluster. It contains more than 8000 galaxies and has a mass of more than ten million billion Suns. The Shapley Supercluster is, in fact, the most massive galaxy cluster within a billion light years, and we and every galaxy in our corner of the Universe are moving toward it.

So as we hurtle through the cosmos, gravity shapes the path we travel. We’re pulled towards the Great Attractor, and despite its glorious title, it appears, in fact to be a perfectly normal collection of galaxies, which just happens to be hidden.

What do you think? What are you hoping we’ll discover over in the region of space we’re drifting towards?

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

Watch a Bright Star Disappear Behind the Moon Monday Night

Ever dabbled in the occult? You’ll have your chance Monday night March 10 when the waxing gibbous moon glides in front of the star Lambda Geminorum for much of North America, occulting it from view for an hour or more. Occultations of stars by the moon happens regularly but most go unnoticed by casual skywatchers. Lambda is an exception because it’s one of the brighter stars that happens to lie along the moon’s path. Shining at magnitude +3.6, any small telescope and even a pair of 10×50 or larger binoculars will show it disappear along the dark edge of the moon. 

Map showing where the occulation of Lambda Gem will be visible. Credit: International Occultation Timing Assn. (IOTA)
Map showing where the disappearance (right half of tube-like figure) and reappearance of Lambda Gem will be visible. Credit: International Occultation Timing Assn. (IOTA)

With a telescope you can comfortably watch the star creep up to the moon’s edge and better anticipate the moment of its disappearance. The fun starts a few minutes before the impending black out when the moon, speeding along its orbit at some 2,280 mph (3,700 km/hr),  draws very close to the star. During the final minute, Lambda may seem to hover forever at the moon’s invisible dark limb, and then – PFFFT – it’s gone! Whether you’re looking through telescope or binoculars, the star will blink out with surprising suddenness because the moon lacks an atmosphere.

Disappearance and reappearance seen from Minneapolis, Minn. Monday night. I've lightened the moon so you can see the dark limb. You'll likely not see this edge in a telescope because of glare. Stellarium
Disappearance and reappearance seen from Minneapolis, Minn. Monday night. I’ve lightened the moon so you can see the dark limb. You’ll likely not see this edge in a telescope because of glare. Stellarium

If there was air up there, Lambda would gradually dim and disappear. Even without special instruments, early astronomers could be certain the moon had little if anything to protect it from the vacuum of space by observing occultations.

As the moon moves approximately its own diameter in an hour, you can watch Lambda re-emerge along the bright limb roughly an hour later, though its return will lack the drama and contrast of a dark limb disappearance. While occultations allow us to see how swiftly the moon moves in real time as well as provide information on its atmosphere or lack thereof, real science can be done, too.


Planets also are occasionally occulted by the moon. Time lapse of Venus’ disappearance on May 16, 2010

Observers along the occultation boundary in the southern U.S. can watch the star pop in and out of view as it’s alternately covered and uncovered by lunar peaks jutting from the moon’s limb. Before spacecraft thoroughly mapped the moon, careful timings made during these “grazing occultations” helped astronomers refine the profile of the moon’s limb as well as determine elevations of peaks and crater walls in polar regions. They can still be useful for refining a star’s position and motion in the sky.

The moon’s limb can also be used much like a doctor’s scalpel  to split unsuspected  double stars that otherwise can’t be resolved by direct observations. Take Lambda Gem for instance. We’ve known for a long time that it totes around a magnitude +10.7 companion star 10 arc seconds to its north-northeast,  but previous occultations of the star have revealed an additional companion only a few hundredths of an arc second away orbiting the bright Lambda primary. The star plays a game of hide-and-seek, visible during some occultations but not others. Estimated by some as one magnitude fainter than Lambda, keep an eye out for it Monday night in the instant after Lambda goes into hiding.


Lunar occultation and reappearance of Antares Oct. 21, 2009

I watched just such a  “two-step” disappearance of Antares and it fainter companion some years back. With brilliant Antares briefly out of view behind the moon’s limb, I easily spotted its magnitude +5.4 companion just 2.5 arc seconds away – an otherwise very difficult feat at my northern latitude.

Want to know more about things that disappear (and reappear) in the night? Make a visit to the International Occultation Timing Association’s website where you’ll find lists of upcoming events, software and how to contribute your observations. If you’re game for Monday night’s occultation, click HERE for a list of cities and times. Remember that the time show is Universal or Greenwich Time. Subtract 4 hours for Eastern Daylight, 5 for Central, 6 for Mountain and 7 for Pacific.  Wishing you clear skies as always!