Category Archives: Cosmology

V774104: The Solar System’s new most distant object

Artist’s concept of trans-Neptunian object V774104 beyond the Kuiper Belt, with the dim sun in the distance

Scott Sheppard (Carnegie Institution for Science), Chad Trujillo (Gemini Observatory), and David Tholen (University of Hawai’i) discovered a new object in the distant reaches of the Solar System last month and designated it Object V774104. V774104 lies 103 au away in the direction of west-central Pisces — that’s 9.6 billion miles or 15.4 billion km. This would put it almost three times as far away as Pluto, and even well beyond the Kuiper Belt. Sheppard announced the discovery at last week’s meeting of the Division for Planetary Sciences of the American Astronomical Society.

Prowling the outer Kuiper Belt for large, distant members of our solar system has turned up a zoo of remarkable finds in recent years. There’s Eris, for example which triggered a divisive debate about Pluto’s planetary status; Sedna, whose orbit carries it out to more than 900 astronomical units (1 a.u. is the mean Earth-Sun separation); and 2007 OR10, both very distant (87 a.u.) and one of the reddest objects in the solar system.

Sky and Telescope
November 21, 2015

During an observing campaign for new trans-Neptunian objects utilising the 8.2-meter Subaru Telescope on Mauna Key and the Dark Energy Camera mounted on NOAO’s 4-meter Víctor M. Blanco Telescope in Chile, the researchers noticed last month a previously unseen bright speck of light moving slowly relative to the background stars.

November 12th, 2015

V774104 announced on November 10

Sheppard announced V774104 on November 10 at a meeting held in National Harbor, Maryland. Yeah, V774104’s a weird name. There are far too many objects in space for all of them to be given real names, so the vast majority just get these strange combinations of letters and numbers to identify them with. I compiled the following information on a few of the major objects with real names:

Solar System DataThe planets and the Major Asteroid Belt objects all have relatively circular orbits, especially those nearest the sun. The orbits of Saturn, Uranus, and Neptune are a little more elliptical than the inner five; and those of Pluto and the Kuiper Belt, even more so.

The planets all orbit near a plane radiating out from the Sun’s equator, but those farthest out tend to be a little more inclined. Pluto and Eris have inclinations of 17 degrees and 44 degrees respectively, and the large asteroid Pallas is inclined at 34 degrees. At Oort Cloud distances, many of the inclinations approach 90 degree, and the plane becomes a hollow sphere.

Planets in the Solar System revolve in their orbits in a prograde manner, i.e., in the same direction as the Sun’s rotation on its axis. With the exceptions of Venus and Uranus, they also rotate progradely on their axes; but these two have retrograde rotations.

Most satellites of planets also revolve around them in the prograde sense. (In the case of the satellites of Uranus, this means they revolve in the same sense as Uranus’s rotation, which is retrograde relative to the Sun.) The exceptions are generally small and distant from their planets, except for Neptune’s satellite Triton, which is large and close. It is believed that these retrograde satellites, including Triton, were formed in other locations and later captured by their planets.

The Oort Cloud is a theoretical hollow sphere containing trillions of icy objects too far away for us to see them yet. The reason we know about the Oort Cloud is by studying the comets that occasionally fall toward the Sun from it. The distance and location from which a body has fallen toward the sun can be estimated by its velocity.

About as far away as the Pioneer probes have gone in 43 years

At 103 AU, or 9.6 billion miles, V774104 is about as far away as the twin Pioneer probes, which have been traveling since 1972 and 1973. It’s beyond the main Kuiper Belt, but not far enough away to be considered part of the Oort Cloud. It is believed to be the most distant object ever seen in orbit around the sun yet, though we’ll undoubtedly find many more as our instruments and techniques keep on improving. (One AU is the average distance between earth and the Sun, or approximately 93 million miles.)

V774104 discovery images

Anyway, Shepherd’s team found the new worldlet while exploring a section of space way out beyond Pluto to see if anything was moving there. They do this by taking pictures of exactly the same space several hours apart and comparing them. The animated gif on the right shows two such pictures. While background stars far beyond our solar system appear stationary, the newly discovered V774104 clearly jumps from one spot to another near the center of the picture. The frame is 0.7 arcminute wide.

This is not because of V774104’s own movement through the outer reaches of the solar system. At that distance from the sun, it orbits too slowly. Instead, it is earth’s movement in its own orbit that seems to make it jump. This is called parallax.

To get a simple idea of how parallax works, hold your thumb at arm’s length. First close your right eye and look at your thumb with your left eye. Next, close your left eye and look at your thumb with your right eye. Notice how your thumb seems to jump from one side to the other as you change eyes? This represents the pictures taken from two points in earth’s orbit a few hours apart. Anything in the pictures will show some parallax, but only objects in the solar system will be close enough to notice it. (Some of the closest stars show enough parallax to detect, but only if the pictures are taken six months apart from opposite sides of the planet’s orbit.)

Parallax is how asteroids, comets, and dwarf planets are nearly always discovered. It was also used originally to estimate the distance between the sun and a few of the nearest stars, before better techniques were invented.

From the amount of parallax, Sheppard’s team calculated that V774104 is about 103 astronomical units (AU) away from the sun. Then based on its brightness, they estimated its diameter to be between 300 and 600 miles (500 and 1000 km), or less than half that of Pluto. Although it’s too soon to say for sure, it appears to have an orbit maybe two or three times larger than Pluto’s. (The orbit can be determined accurately only after at least a year of observation.)

While it is clearly one of the most distant planetary bodies ever observed in the solar system, it will require more observation be sure it holds that record during its entire orbit.

The three most distant dwarf planets known all have eccentric orbits, and none of them could have formed in their current locations, Sheppard says. They may have been perturbed into these orbits, either by an encounter with another star in the solar system’s early years, or by a still undiscovered Mars- or Earth-sized planet lurking in the outer solar system. “We can’t explain these objects’ orbits from what we know about the solar system,” he said.

The discovery reflects a number of extreme solar system surveys that are using telescopes with both big mirrors and large fields of view—necessary to find faint solar system objects that could be almost anywhere in the sky. Unlike many searches for distant objects, which peer into the solar system’s plane, Sheppard is training Subaru on swaths of the sky an average of 15° away from the ecliptic, the better to find other weird objects.

“We want to find a bunch of these objects like VP113 we found last year,” Sheppard said. “There’s several different theories about how these distant objects could have got out there on these eccentric orbits. And all these different theories predict different orbital distribution and orbital population. So if we can find 10 or so of these objects, then we can start determining which theories of the formation of these objects are correct.”

Kuiper belt - Oort cloud-en.svg

The diagram above, from Wikipedia, shows the relative locations of several parts of the Solar System. The new object is too new to appear here, but it would be off the edges anyway. The outer edges of the Oort Cloud (if shown) would extend hundreds of feet out beyond the edges of the picture in all directions.


It’s a Big, Big, Big, Big, Big Universe

Area , smaller than the diameter of the full moon as seen from earth -- Big Universe

We Live in a Big, Big, Big, Big, Big Universe

This is just one very small piece of sky, much smaller than the diameter of the full moon as seen from earth. It looks completely empty and black to the unaided eye, but the Hubble Space Telescope stared at it for several days and finally collected enough light to photograph all these galaxies in it. (You can’t see individual stars here. Every dimmest, tiniest, all-but-invisible speck of light is a whole galaxy. The original, very large photograph shows many times more galaxies than you can see even here.)

When I studied science in high school almost 60 years ago, we learned that astronomers estimated there were between 100 billion and a trillion (1,000 billion) stars in our Milky Way Galaxy. They also estimated there were between 100 billion and a trillion galaxies in the known universe. (This doesn’t imply the Milky Way is necessarily an average galaxy in all ways, of course. It is not.)

It always struck me as a little bit strange that the range of estimated stars per galaxy and the range of estimated galaxies in the known universe were the same, but it’s just a coincidence with no meaning except inside my head, and maybe inside the heads of the astronomers doing the estimating. (Yes, coincidences are sometimes really just coincidences.)

More recently, I’ve read and heard exactly the same range of numbers: 100 billion from one source, a trillion from another source, and several estimates between for each number. These particular ranges of estimates have remained the same for more than half a century. The most common actual estimate seemed, until recently, to be about 200 billion each: 200 billion stars, on average, in each of 200 billion galaxies. In the past couple of years, though, I seem to have read estimates of a trillion galaxies in the known universe and a trillion stars in an average galaxy more and more often. (This doesn’t mean the universe is getting bigger. It really is, but that’s a different story. What this means is that the estimates are finally getting better. And bigger.) These are the figures we’ll play with here: a trillion galaxies and an average of a trillion stars per galaxy.

That’s a lot of stars.

How many stars does that make? It’s 1,000,000,000,000 times itself; 1,000,000,000,000 squared. That’s 1,000,000,000,000,000,000,000.000, or a septillion stars in the known universe. It’s an unimaginably huge number. The human mind simply didn’t evolve to comprehend any number that large, so we have to break it down and illustrate it some way.

This is why the stars of the sky have been described as “innumerable.” They literally are. Not the ones you can see on a clear night with your unaided eyes. There are only a few thousand of those, and even that assumes you have really good eyes and a really dark place from which to observe. But nobody — nor even everybody all put together — could count all the stars in space, else we wouldn’t have to estimate.

But there are a lot of us, too.

There are more than 7.4 billion (7,400,000,000) people on earth right now. If we were all lined up and jammed together so that we each had only one foot of space (about 30 cm) in which to stand, we’d make a line 1,401,515 miles (2,340,530 km) long. Long enough to stretch all the way around the planet 55 times with enough over to tie a nice bow.

But suppose we were all given extremely powerful telescopes and asked to count all the stars in the “known universe.” Then suppose every human now alive could count a star every second of every day, 24 hours a day and seven days a week, and nobody ever counted the same star twice. It would take us just over 4,284,174 years to finish the job.

Even that vast number of stars, along with the accompanying planets, asteroids, comets, nebulae, black holes and all the other inhabitants of the cosmological zoo may not comprise the whole universe; it’s the part we can see and study, at least in principle. The part we call “the known universe.” If there’s more — and there almost certainly is — it’s so far away that even the light from it could not have reached us in all the 13.8 billion years the universe has existed. There doesn’t seem to be any possible way humans will ever be able to see it or study it directly.

The moral of this story is, the universe is big. Really big. Fantastically big. It’s far, far bigger than you or I can possibly imagine.

Great Pumpkin Asteroid Flyby Halloween Weekend

Halloween Great Pumpkin Asteroid

A large asteroid 1,300 feet in diameter will fly by our planet tomorrow at 1:01 p.m. EDT at about 79,000 m.p.h. Asteroid 2015 TB145, which was just discovered on October 10, has been christened the “Great Pumpkin Asteroid” by NASA. It will pass us at a distance of about 300,000 miles, or about 1.3 times the distance of the moon’s orbit. There will be no danger to earth; but it’s still considered close, as cosmic distances go.

Scientists are gearing up to take advantage of the close encounter to study the asteroid as it zips by. As far as we know, there will not be another one this large and this close for 12 years.

The Great Pumpkin Asteroid won’t be visible to the naked eye, but amateur astronomers with proper telescopes will be able to see it late tonight and before dawn tomorrow morning.

The gravitational force of the asteroid is so small at that distance that it will have no detectable effect on earth or the moon.

The Great Pumpkin Asteroid has a weird orbit.

The video above shows the solar system (not to scale), demonstrating the Great Pumpkin Asteroid’s strange orbit. The asteroid crosses earth’s orbit slightly before the 15 second point.

The asteroid belt forms a donut shaped cloud between the orbits of Mars and Jupiter. The Great Pumpkin Asteroid has a long narrow orbit that goes out almost as far as Jupiter’s orbit and then falls back to very near the sun about every three years, but it moves at a steep angle to the plane of the solar system. Because of this strange orbit, it’s possible this might be a tailless comet and not a true asteroid. Observations this weekend should tell us for sure.

The Great Pumpkin Asteroid is an NEO.

2015 TB145 was just discovered on Oct. 10. Asteroids and comets that cross earth’s orbit are called “earth crossers” or “near-earth objects” (NEO), and there are believed to be several million of them.

Since only about 13,000 NEOs have been actually detected to date, there are obviously lots of potentially dangerous ones cruising through Earth’s neighborhood unseen. Fortunately, most are relatively small. NASA believes about 95 percent of the biggest ones — those that could threaten human civilization — have been found; and none of them is a danger to us for at least the next few hundred years.

Those smaller than the Great Pumpkin Asteroid can still be dangerous.

However, because of their tremendous speed, even some of the many smaller ones could cause a great deal of death and destruction if they struck our planet. The video below is stitched together from several Russian dash-cams and other cameras. The pictures were taken February 15, 2013, while drivers watched in amazement as a small asteroid exploded high in the atmosphere over Chelyabinsk Oblast with the force of 30 Nagasaki-type atomic bombs.

The “Chelyabinsk meteor,” as it is known, was only estimated to have been 65 feet in diameter — many times smaller than the one now approaching earth orbit. Yet about 1,500 people were injured seriously enough to seek medical treatment, mostly from broken glass that shattered when windows were blown in by the powerful shock wave. Around 7,200 buildings were damaged in six cities by the shock wave; but, fortunately, there were no known fatalities. It could have been far worse if it had exploded nearer the ground.

The Chelyabinsk meteor is the only meteor — or asteroid — ever confirmed to have resulted in a large number of injuries. So far.

Russian Asteroid 2013-02-16That was the largest known natural object to have entered Earth’s atmosphere since the 1908 Tunguska event, which destroyed a wide, remote, forested area of Siberia; and it took us completely by surprise. We had no idea it was coming. A large chunk of it was eventually recovered (above left).

Readers who watched their TVs as 21 separate fragments of Comet Shoemaker-Levy 9 pounded Jupiter for a week between July 16 and 22, 1994, most of them leaving scars large enough to swallow our planet whole, will understand the danger these unguided missiles present. Fortunately, the very large ones are rare.

One of NASA’s many duties is to locate dangerous NEOs and find ways to deflect them if necessary. The dinosaurs would have appreciated their help.


Super Blood Moon Lunar Eclipse Redux

In case you missed the “Super Blood Moon Lunar Eclipse” Sunday night, as I did, here’s a five-second replay. All four hours of it condensed for quick viewing.

I went out three times to see the event and maybe take some pictures, but the cloud cover was too complete. The moon was just a hazy glow from my apartment in Fort Worth.

Enjoy this replay. Be sure to watch it full size.

Super Blood Moon Lunar Eclipse

A moderately rare “super blood moon” lunar eclipse will be viewable in the sky tonight for those living in North and South America. However, the word “super” should be taken with the proverbial grain of salt. It’ll be slightly larger than average because of its position in orbit, but you probably won’t notice the difference. What you will notice is the reddish color.

Here’s the schedule for Americans again. For most of the country, the moon will be low above the eastern horizon. For people in Colorado, it’ll be in eclipse when it rises. It’ll begin to move into the earth’s shadow at 9:07 P.M. Eastern Time. The eclipse will begin with a bite out of its lower left side.

Note: The previous paragraph should have said “west of Colorado” instead of “in Colorado.”

It’ll take just over an hour for the moon to pass completely into earth’s shadow, and its last sliver will slip into darkness at 10:11. It’ll stay dark for more than an hour; then start to lighten again at 11:23, and be completely out of earth’s shadow at 27 minutes after midnight. Don’t forget to adjust for your time zone.

People in Europe and Africa can see the eclipse in the early hours after midnight.

super blood moon lunar eclipse over water
super blood moon lunar eclipse over water

A blood moon is a special lunar eclipse. It happens when Earth completely blocks sunlight from reaching the moon except for a ring of light refracting through the atmosphere. Instead of going dark, the moon is lit by that refracted light that leaks around the planet, essentially reflecting all of Earth’s sunsets and sunrises onto the surface of the moon at once and giving it its reddish color.

A super moon is when the moon is nearest Earth in its orbit, so it appears as much as 14% larger in area than average. When the two events happen together, we call it a super blood moon lunar eclipse.

See my previous post here for more info.

If you miss it for any reason, you can view it here later: Video: Missed the Blood Moon? Watch the Event Unfold Through NASA’s Footage.

The next total lunar eclipse won’t happen until January 2018.


  • NASA
  • Bill’s Blog

Super Blood moons in prophecy? Really?

John Hagee is wrong. The flamboyant and ego-inflated pastor of the huge Cornerstone megachurch of San Antonio likes prophecy and signs in the sky. He believes the sky is “God’s billboard,” and that God is writing messages on it for us. The “super blood moon” is supposed to be one of those messages. Not for the first time, Pastor John Hagee is wrong. (No, he’s not the only one. Others are making similar claims. He’s just probably the most prominent one.)

Super Blood Moon Schedule

There is nothing mysterious or even very unusual about the eclipse we’re going to have in a couple of days. Even the word “super” is misleading. Yes, because of its position in orbit, it’ll look a little bit larger than usual; but not so much you’re likely to notice it. Take all the hype with a grain of salt.

In just two days, on the night of Sunday, September 27th, 2015, if the weather permits, a “rare super blood moon” lunar eclipse will be visible in the night sky for people in North and South America. (Well, it’s unusual, but not really all that rare.)

Here’s the schedule. For most of the country, the moon will be low above the eastern horizon. For people in Colorado, it’ll be in eclipse when it rises. It’ll begin to move into the earth’s shadow at 9:07 P.M. Eastern Time. The eclipse will begin with a bite out of its lower left side.

It’ll take just over an hour for the moon to pass completely into earth’s shadow, and its last sliver will slip into darkness at 10:11. It’ll stay dark for more than an hour; then start to lighten again at 11:23, and be completely out of earth’s shadow at 27 minutes after midnight. Don’t forget to adjust for your time zone.

People in Europe and Africa can see the eclipse in the early hours after midnight.

super blood moon

A “super moon” is when the moon is nearest Earth in its orbit, so it appears as much as 14% larger than when it is farther away. This happens because its orbit around earth — like all orbits — is an ellipse, not a circle.

A “blood moon” is an eclipse when the moon happens to be exactly — or almost exactly — in the plane of earth’s orbit around the sun. The moon’s orbit around earth is tilted about five degrees with respect to earth’s orbit around the sun, so the moon crosses the plane of earth’s orbit about every 14 days.

When this coincides with a lunar eclipse, earth comes between the sun and the moon, almost shutting off all light from the sun to the moon. The only sunlight reaching the moon then is refracted around the earth by its atmosphere. Instead of going dark, the moon is lit dimly by that refracted light that leaks around the planet, essentially refracting all of Earth’s sunsets and sunrises onto the surface of the moon at one time and giving it a deep reddish color. We have a “blood moon.”

When the two events happen together, like this time, we call it a “super blood moon” lunar eclipse. It’s unusual, but it’s not mysterious; and there’s absolutely nothing supernatural about it.

The next total lunar eclipse won’t happen until January 2018. If you miss this one for any reason, you can view it here later: Missed the Blood Moon? Watch the Event Unfold Through NASA’s Footage.

Here’s Neil DeGrasse Tyson, everybody’s favorite astrophysicist, discussing a previous “blood moon.”

For more information about eclipses in general, watch Crash Course Astronomy with Phil Plait, the Bad Astronomer.


The Solar System (to scale)

This is a great solar system demonstration!

You start your model solar system with a blue marble with patterns vaguely reminiscent of oceans and continents. That’s your earth. The pea-sized moon is a couple of feet away. Build it in the Black Rock desert in Nevada, where you have plenty of room. It will be seven miles in diameter.

Your sun, about 616 feet from your earth, will be about 5 feet across. The sun’s diameter is a hundred times that of our planet.

Mighty Jupiter, roughly the size of a soccer ball, is 3,326 feet out from your sun, or roughly 0.6 miles. Saturn, with its glorious rings, is a little smaller and over a mile out. Neptune, called “the edge of the solar system,” is 3 1/2 miles out.

If you reduced your model solar system to fit on a large sheet of paper, the biggest planets would be invisible except under a microscope. It’s that huge.

When the real sun rises and finds you standing on your earth’s orbit, your 5-foot model sun in the distance appears the same size as the real sun 93 million miles away. By this, you know the orbits of your model solar system are correct.

Neptune, of course, is not really “the edge of the solar system.” It just happens to be the last full-fledged planet. If you included Pluto, which we used to call a planet, it would be about four miles from your sun, making your model solar system eight miles across.

If you also included the Oort cloud, which contains millions of comets and dwarf planets — maybe billions — stretching half-way to the nearest star, your model would reach half-way around the world in all directions and just about meet on the opposite side. It would almost cover the entire surface of the real earth.

I agree, “It’s staggering!”


Double Eclipse of the Sun

Double Eclipse of the sun

NASA’s Solar Dynamics Observatory (SDO) satellite caught an exceptionally rare sight on September 13, a double eclipse of the sun. The Earth and the moon simultaneously passed across the face of the sun. Back on earth, the residents of Antarctica were treated to a partial solar eclipse at the same time.

Science News explains:

Launched in 2010, SDO studies the sun’s churning atmosphere. Its tilted geosynchronous orbit gives the spacecraft a nearly uninterrupted view, but on rare occasions like this, the Earth or moon can get in the way.

A double eclipse like this is impossible to see from earth. It was only visible because the satellite taking the pictures was outside earth’s orbit, so the earth and moon could appear between it and the sun at the same time.

From the satellite’s perspective, earth passed in front of the sun first, covering it completely and then moving off at the top. Our atmosphere caused the fuzzy edge. As earth finished its transit, the smaller, faster moving moon crossed below it and exited toward the left. Not possessing an atmosphere, the moon produced a sharp edge to its shadow.

An animation here might help make the mechanics of it easier to visualize.

SDO was launched in 2010 into a tilted geosynchronous orbit to study the sun’s turbulent atmosphere; so it has an almost uninterrupted view, but the Earth or moon can occasionally get in the way. A double eclipse like this is extremely rare.


Exoplanets: Crash Course Astronomy

On July 9, I posted a gif of Pluto and Charon orbiting their mutual center of mass, located in a point of space between them. I said this about the video:

We usually think of a satellite orbiting its primary. In this case, it would be Charon, the tiny dot, orbiting Pluto, the larger dot. But we’ve always known this is not really the case. The two objects orbit each other. More accurately, they both orbit their common center of mass (or center of gravity).

Here’s a simulation from Bad Astronomy showing the same principle. This represents a planet and a star instead of a moon and a planet, but they work exactly the same way. The center of mass of the system is called the barycenter. Phil Plait, the “Bad Astronomer,” describes it this way:

barycenter animation

As you can see in the animation, the planet makes a big circle and the star makes a small one. And if you watch closely you’ll see they’re always on opposite sides of the barycenter; when the planet is on the left of its orbit, the star is 180° around on its right.

This wobble in the star’s movement was used to detect most of the first exoplanets, or planets of other stars than our sun. The first two were found in 1992. It wasn’t until three years later, in 1995, that the third was discovered. Now we’ve identified almost 2,000 for sure, ranging in size from smaller than Mercury to several times as large as Jupiter. About 3,000 more probable exoplanets are waiting for verification.

There may very well be more planets in the universe than there are stars.