Universe Today

February 25, 2008December 26, 2015 by Tammy Plotner

Two Meteor Showers Sparkle the Skies… Beginning Tonight!

Are you ready for more meteor showers? Thanks to the after midnight rise of the Moon, many of us might have the clear skies to enjoy the Delta Leonid and Gamma Normid Meteor showers which peak around this date. While the activity isn’t dramatic for either one, these two rare meteor showers are a great time for observers to catch a shooting star!

For SkyWatchers who live in a dark area, be on the lookout for what is probably an ancient stream belonging to the Virginids. According to the International Meteor Organization (IMO) the “Northern hemisphere sites have a distinct advantage for covering this stream, especially this year as the waning gibbous Moon will rise around or after midnight at the peak for sites north of 35Â° N latitude. Southern hemisphere watchers should not ignore the stream, as they are better-placed to note many of the other Virginid radiants, but with moonrise as early as 22h 30m at 35Â° S latitude on February 25, conditions are not ideal.”

To take advantage of this opportunity, keep an eye on the constellation of Leo where meteors will seem to originate around mid-way in the Lion’s back. This is good news since the constellation itself will be visible nearly all night! The fall rates are slow – one about every 30 minutes – but with nearby Saturn to liven up the show, it’s a great time to catch a Delta Leonid telescopically. For the most part, the meteors you spot will be faint and blue. Using binoculars in this circumstance is definitely helpful as you’ll be able to see the trail far longer.

For the Southern Hemisphere, keep an eye out for the Gamma Normids, too! While they are similar to sporadic meteors, they are known to sometimes make a sharp jump in fall rate on either side of their peak time. IMO suggests: “Post-midnight watching yields best results, when the radiant is rising to a reasonable elevation from southern hemisphere sites. First quarter Moon on March 13 is thus excellent news, as it will set before midnight.” Again, the hourly rate is slow, but look for one about every 20 minutes. (Sorry, Northern Hemisphere… We can’t see Norma.) Shower members are swift with the brightest meteors often having a yellow color.

Neither the Delta Leonids, nor the Gamma Normids will be a spectacular show… But don’t despair if you don’t have clear skies tonight. Both meteor showers will be active until mid-March. The fun part is spotting one and understanding where it originated! While no definitive information can be found on the Gamma Normids, the Delta Leonids are thought to possibly be related to the minor planet 1987 SY – also known as asteroid 4450 Pan. The 1.6 km wide Apollo asteroid was discovered on September 25, 1987, by Caroline Shoemaker at the Palomar observatory and just made a flyby of the Earth on February 19, 2008, at a distance of 15.9 lunar distances (0.0408 AU). Perhaps we’ll be lucky and it will have left a bit more visible debris for us to enjoy!

February 25, 2008December 26, 2015 by Tammy Plotner

Find the Zodiacal Light

Look to the West, just after the Sun has set, and you might see a dimly glowing triangle rising up from the horizon. This is the zodiacal light, where sunlight reflects off dust particles in the Solar System. If you live in the mid-northern latitudes, look for the zodiacal light in the evening in Autumn and in the morning in Spring.

Now that the Moon has departed from the early evening sky, this is a good time in the northern hemisphere to watch the western skyline for the evening zodiacal lights. If you live in an area where light and air pollution isn’t heavy, you stand a very good chance of seeing the interplanetary dust in the plane of our own solar system lit by the setting Sun, and that is the zodiacal light.

In the Spring in the northern hemisphere, the ecliptic plane extends upright from the western horizon. (If you live in the southern hemisphere, you need to watch the eastern horizon before dawn after New Moon.) When the Sun is just below the horizon, we can see a ghostly glowing pyramid. But, what is the zodiacal light?

Sunlight is back-scattered off small interplanetary dust particles, perhaps some of them from the very formation of our solar system itself. However, a lot of these tiny, millimeter sized splinters are from asteroids – or debris ejected from comets. Some of these particles are initially distributed in the trails that cause meteor showers, but whole lot of the dust eventually gathers along the ecliptic plane.

For the ultra-tiny particles, the radiation and solar wind disperses them beyond the confines of our solar system. The larger particles spiral inwards, pulled towards the Sun by gravity and form a flattened disc – a very low density cloud of dust, coincident with the plane of the solar system. Sunlight absorbed by the particles is re-emitted as invisible infrared radiation. This re-radiation causes the particles to spiral slowly into Sun, thus requiring continuous regeneration of the dust particles composing this cloud. The reflective particle disc makes its home in the same path the planets take around the Sun – the ecliptic. This imaginary path across the sky is where we here on Earth see the Sun and Moon, and it’s also home to the constellations of the zodiac!

Using the same celestial mechanics that give us times of solstice, equinox, lunar and solar eclipses, it only stands to reason there comes a time when the ecliptic plane appears nearly vertical from a certain vantage point. For the northern hemisphere it’s west in the spring and east in the fall. For the southern hemisphere it’s just the opposite! When the plane is near vertical, the thick air near the horizon doesn’t block out relatively bright reflecting dust and we see the zodiacal light!

Head out to an open horizon area where you’re away from man-made light pollution. As the skies grow dark, look for a faint pyramid of light spread out over a very large area of the sky. The zodiacal light won’t be as dramatic as photos show it. Near its base at the horizon, it can measure as broad as 40 degrees (two handspans), and stretch up as high as 60-80 degrees under good conditions. The spectrum of the zodiacal light is the same as the solar spectrum, reinforcing the deduction that it is merely sunlight reflected by dust in the plane of the planets. If you think you see a ghostly glow, you’re probably right!

If you’ve seen the zodiacal light, let us know!

February 25, 2008April 26, 2016 by Ian O'Neill

Record Breaking “Dark Matter Web” Structures Observed Spanning 270 Million Light Years Across

It is well documented that dark matter makes up the majority of the mass in our universe. The big problem comes when trying to prove dark matter really is out there. It is dark, and therefore cannot be seen. Dark matter may come in many shapes and sizes (from the massive black hole, to the tiny neutrino), but regardless of size, no light is emitted and therefore it cannot be observed directly. Astronomers have many tricks up their sleeves and are now able to indirectly observe massive black holes (by observing the gravitational, or lensing, effect on light passing by). Now, large-scale structures have been observed by analyzing how light from distant galaxies changes as it passes through the cosmic web of dark matter hundreds of millions of light years across…

Dark matter is believed to hold over 80% of the Universe’s total mass, leaving the remaining 20% for “normal” matter we know, understand and observe. Although we can observe billions of stars throughout space, this is only the tip of the iceberg for the total cosmic mass.

Using the influence of gravity on space-time as a tool, astronomers have observed halos of distant stars and galaxies, as their light is bent around invisible, but massive objects (such as black holes) between us and the distant light sources. Gravitational lensing has most famously been observed in the Hubble Space Telescope (HST) images where arcs of light from young and distant galaxies are warped around older galaxies in the foreground. This technique now has a use when indirectly observing the large-scale structure of dark matter intertwining its way between galaxies and clusters.

Astronomers from the University of British Columbia (UBC) in Canada have observed the largest structures ever seen of a web of dark matter stretching 270 million light years across, or 2000 times the size of the Milky Way. If we could see the web in the night sky, it would be eight times the area of the Moons disk.

This impressive observation was made possible by using dark matter gravity to signal its presence. Like the HST gravitational lensing, a similar method is employed. Called “weak gravitational lensing”, the method takes a portion of the sky and plots the distortion of the observed light from each distant galaxy. The results are then mapped to build a picture of the dark matter structure between us and the galaxies.

The team uses the Canada-France-Hawaii-Telescope (CFHT) for the observations and their technique has been developed over the last few years. The CFHT is a non-profit project that runs a 3.6 meter telescope on top of Mauna Kia in Hawaii.

Understanding the structure of dark matter as it stretches across the cosmos is essential for us to understand how the Universe was formed, how dark matter influences stars and galaxies, and will help us determine how the Universe will develop in the future.

“This new knowledge is crucial for us to understand the history and evolution of the cosmos […] Such a tool will also enable us to glimpse a little more of the nature of dark matter.” – Ludovic Van Waerbeke, Assistant Professor, Department of Physics and Astronomy, UBC

Source: UBC Press Release

February 24, 2008April 26, 2016 by Ian O'Neill

Space Debris May be Catastrophic to Future Missions (and Google Earth is Watching…)

Kessler Syndrome could be a frightening situation for space travel. No, it’s not a health risk to the human body in zero-G and it’s not a psychological disorder for astronauts spending too much time from home. Kessler Syndrome is the point at which space travel becomes impossible without hitting into a piece of space junk, jeopardizing missions and risking lives. In extreme predictions, space debris from our constant littering of low Earth orbit, collisions between bits of rubbish may become more and more frequent, causing a catastrophic cascade of debris multiplying exponentially, falling through the atmosphere and making space impassable.

In the meanwhile, space mission controllers must be acutely aware that there could be an odd bolt or piece of old satellite flying toward their spaceship at velocities faster than the fastest rifle shot. Spare a thought for the space debris trackers as they try to keep a record of the 9,000+ pieces of junk currently orbiting our planet… but wait a minute, Google Earth can give us a ringside seat!

Strict international civil aviation-style laws may need to be imposed on the worlds space agencies if future generations of the human race are going to make it in space. This stark warning comes from Tommaso Sgobba, Director of the International Association for the Advancement of Space Safety, who will be presenting his case to the United Nations in April. Sgobba’s main argument comes from the danger associated with the escalating accumulation of space debris in Earth orbit, should these high speed bits of junk hit a spaceship, satellite or an astronaut, death and disaster may ensue. It may get worse than this, possibly paralysing the Earth from having access to space at all.

“Failure to act now to regulate space to protect property and human life would be pure folly.” – Tommaso Sgobba.

Other scientists agree with Sgobba, recommending that future missions in to space abide by some strict codes of practice (possibly more strict than those imposed on international civil aviation) to drastically cut the rate of orbital littering by the 20 countries currently able to send stuff into space.

Even the most tightly controlled missions, such as the International Space Station, are expected to shed bits and pieces over the course of their lifetimes. Space junk comes in all shapes and sizes and can be anything from a small screw to entire dead satellites. Recorded examples of space junk include an old glove lost by Ed White during the first ever US space walk in 1965 (during the Gemini-4 mission), a camera that Michael Collins let slip in space in 1966 (during the Gemini-8 mission) and a pair of pliers that International Space Station astronaut Scott Parazynski dropped during an EVA last year.

Some space debris near misses include:

Space Shuttle dodge: Space Shuttle Atlantis had to avoid collision with a piece of a Russian satellite by carrying out a seven second burn of its engines in 1991.
Aircraft scare: Bits of an Russian ex-spy satellite fell through the atmosphere coming very close to a Latin American Airbus, carrying 270 passengers in 2006.
Personal injury: fortunately there is only one documented account of someone being hit by a piece of debris on the ground. In 1997 a woman from Oklahoma was hit on the shoulder by a piece of a fuel tank from a Delta II rocket. She was unhurt and lived to tell the tail.

It is hoped that tighter controls on the rockets, satellites and spacecraft will slow the rate of junk increase, but the problem is already pretty worrying for long-term missions in orbit around the Earth. The two critical regions filling with debris are in low Earth and geosynchronous orbits, a few hundred and 22,300 miles high respectively. Low Earth orbit will cause problems for spacecraft to actually leave the atmosphere and geosynchronous orbit may hinder future communication satellite insertions.

To safeguard our access into space, and avoid an increase in debris-related incidents, action will need to be taken.

Google Earth-watch

During the research on this article, I came across some work being funded by Ministry of Culture of the Republic of Slovenia, Municipality of Ljubljana, where researchers are making debris location data available to the public via a plugin for the Google Earth application. According to the groups blog, the data is taken from a U.S. government-owned space observatory so known space debris (or as the blog calls it “pollution”, which it really is) can be tracked.

On experimenting with the new space debris folder, it really did strike home as to what a problem space junk is becoming. For starters, there is an impossibly thick near-Earth layer and a distinct ring representing the geosynchronous debris. Plus, each item can be selected and information on the individual bits of debris can be found out… see the screenshots to find out what I mean…

Get the space junk plugin for Google Earth (read Google Earth documentation to learn how to use this plugin).

News Source: Guardian.co.uk

February 22, 2008April 26, 2016 by Ian O'Neill

Could Primordial Black Holes Deflect Asteriods on a Collision Course with Earth?

An artists impression of an asteroid belt. Credit: NASA

Primordial black holes (PBHs) are getting mischievous again. These artefacts from the Big Bang could be responsible for hiding inside planets or stars, they may even punch a neat, radioactive hole through the Earth. Now, they might start playing interplanetary billiards with asteroids in our solar system.

Knocking around lumps of rock may not sound very threatening when compared with the small black holes’ other accolades, but what if a large asteroid was knocked off course and sent in our direction? This could be one of the most catastrophic events yet to come from a PBH passing through our cosmic neighborhood…

As a race, we are constantly worried about the threat of asteroids hitting Earth. What if another large asteroid – like the one that possibly killed the dinosaurs around 65 million BC or the one that blew up over Tunguska in 1908 – were to come hurtling through space and smash into the Earth? The damage caused by such an impact could devastate whole nations, or plunge the world as we know it to the brink of extinction.

But help is at hand. From the combined efforts by groups such as NASAs Near Earth Object Program and international initiatives, governments and institutions are beginning to take this threat seriously. Tracking threatening Near Earth Asteroids is a science in itself, and for now at least, we can relax. There are no massive lumps of rock coming our way (that we know of). The last scare was a comparatively small asteroid called “2008 CT1” which came within 135,000 km of the Earth (about a third of the distance to the Moon) on February 5th, but there are no others forecast for some time.

So, we now have NEO monitoring down to a fine art – we are able to track and calculate the trajectory of observed asteroids throughout the solar system to a very high degree of accuracy. But what would happen if an asteroid should suddenly change direction? This shouldn’t happen right? Think again.

A researcher from the Astro Space Center of the P. N. Lebedev Physics Institute in Moscow has published works focusing on the possibility of asteroids veering off course. And the cause? Primordial black holes. There seems to be many publications out there at the moment musing what would happen should these black holes exist. If they do exist (and there is a high theoretical possibility that they do), there’s likely to be lots of them. So Alexander Shatskiy has gotten to the task of working out the probability of a PBH passing through the solar systems asteroid belts, possibly kicking an asteroid or two across Earths orbit.

Shatskiy finds that PBHs of certain masses are able to significantly change an asteroids orbit. There are estimates of just how big these PBHs can be, the lower limit is set by black hole radiation parameters (as theorized by Stephen Hawking), having little gravitational effect, and the upper limit is estimated to be as massive as the Earth (with an event horizon radius of an inch or so – golf ball size!). Naturally, the gravitational influence by the latter will be massive, greatly affecting any piece of rock as it passes by.

Should PBHs exist, the probability of finding one passing though the solar system will actually be quite high. But what is the probability of the PBH gravitationally scattering asteroids as it passes? If one assumes a PBH with a mass corresponding to the upper mass estimate (i.e. the mass of the Earth), the effect of local space would be huge. As can be seen from an asteroid map (pictured), there is a lot of rocky debris out there! So something with the mass of the Earth barrelling through and scattering an asteroid belt could have severe consequences for planets nearby.

Although this research seems pretty far-fetched, one of the calculations estimate the average periodicity of a large gravitationally disturbed asteroids falling to Earth should occur every 190 million years. According to geological studies, this estimate is approximately the same.

Shatskiy concludes that should small black holes cause deflection of asteroid orbits, perhaps our method of tracking asteroids may be outdated:

“If the hypothesis analyzed in this paper is correct, modern methods aimed at averting the asteroid danger appear to be inefficient. This is related to the fact that their main idea is revealing big meteors and asteroids with dangerous orbits and, then, monitoring these bodies. However, if the main danger consists in abrupt changes of asteroidal orbits (because of scattering on a PBH), revealing potentially dangerous bodies is hardly possible.”

Oh dear, we might be doomed after all…

Source: arXiv

February 22, 2008December 26, 2015 by Fraser Cain

Aliens Might Be Moving Stars to Communicate With Us

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You’ve got to love the audacity of this idea. In a recent article at Discover Magazine, virtual reality pioneer Jaron Lanier (you know, the guy with the dreadlocks) proposes that we get working on repositioning nearby stars to form geometric patterns – or at least start looking for places that it’s already been done by aliens.

Move stars around into patterns? That’s pretty crazy stuff. Sure, but there isn’t any physical reason why it isn’t possible; it happens all the time when galaxies collide. Of course, a spray of stars hurled into intergalactic space at random is different from a great big peace sign.

In order to actually move a star requires a gravitational tractor, and engineers are already planning this kind of a mission for a threat closer to home: asteroids. By flying a spacecraft near an asteroid, and fighting against the gravity pulling it down, you can actually pull the asteroid off course. Over a long period of time, you can move the asteroid enough in its orbit to prevent it from striking the Earth.

So scale that idea up. Send out a fleet of these spacecraft to tinker with the orbits of Kuiper Belt objects. These objects could rain into the inner Solar System and prod the Sun’s motion through the galaxy. Over a long period of time (a really really long period of time), you could impart enough of a velocity change to drive your star anywhere you wanted it to go.

With this technique, and a few million years to time to kill, you could line up stars into a formation that shows an intelligence was behind it. The more stars you put into formation, the better your message will be.

One interesting suggestion, made to Lanier by Piet Hut at the Institute for Advanced Study is a multiply nested binary system. Imagine binary systems, orbiting binary systems, orbiting binary systems. With 16 stars in formation, you’d have a shape that mother nature would never arrange on her own, but would be stable for long periods of time. From long distances, astronomers wouldn’t be able to resolve the individual stars, but they’d definitely know something strange was going on.

The advantage to this, of course, is that stars are visible for tremendous distances. Why bother sending out puny radio signals when you can harness the energy of an entire star.

Physicists predict that civilizations will eventually advance to the point that they master all the energy of their home planet, their star system, and eventually their entire galaxy. And if you’re harnessing every watt of energy pouring out of every star in the galaxy, who’d miss a little extra energy being used for communications.

So, uh… let’s get on that.

Original Source: Discover Magazine

February 22, 2008December 26, 2015 by Tammy Plotner

Time to Observe Saturn – Opposition Occurs February 23!

Are you ready to take a closer look at the real “Lord of the Rings”? Then say hello to Saturn as it reaches opposition tomorrow night. With the yellow planet rising around sunset, highest in the south around midnight, and setting around sunrise, now is the time for observers and photographers to enjoy Saturn the most!

Right now Saturn is positioned in Leo about 5 degrees east of the constellation’s Alpha star – Regulus. Look for the asterism of a backwards question mark rising after sunset and the brightest “star” in the group will be Saturn! For observers who use only your eyes try comparing the distances by holding your hand at arm’s length. Saturn and Regulus will be separated by about 3 fingerwidths. Look less than a fistwidth further north and you’ll see a dimmer star – Gamma Leonis. Keep an eye on this trio in the days to come and you’ll easily see Saturn’s movement against the background stars!

For observers with binoculars, it’s possible to see elongations on either side of Saturn which are the beginnings of its ring system trying to resolve. Before you complain about not getting a good enough view, remember what you’re seeing is very much like what Galileo saw when he discovered Saturn in 1610. Saturn on Saturday? Why not! Saturn was named for the Roman god of agriculture and the day Saturday is also named after him.

While you’re watching, think on this… Saturn is the second biggest planet, but itâ€™s also the lightest planet. If there was a bathtub big enough to hold Saturn, it would float in the water! Its diameter is approximately 75,000 miles (120,000 km) and more than 9 Earths could line up across it. It’s composed of 97% hydrogen gas, about 3% helium gas and about 0.05% methane, plus ammonia. One of the reasons it appears slightly flattened is because it is! Saturn rotates in 10 hours, 39 minutes in Earth time and this fast pace is what gives it a unique shape. It takes Saturn almost 30 years to complete an orbit around the Sun!

Now on to observing with a small telescope…

What’s that you say? You can barely see Saturn’s rings? You’re right. At the moment Saturn’s rings are only tilted about 8 degrees from our line of sight. Earth’s equator is tilted 23 degrees and this tilt gives our planet its four seasons. Each year as we orbit around the Sun, our tilt causes different parts of the planet to spend more time in sunlight. Days become longer… nights become shorter! Saturn’s equator is tilted very similar to ours at 27 degrees. This gives Saturn the same seasonal changes as we here on Earth experience. Because of the tilt of Saturn and the thinness of the rings, every 14 years the rings look like they’ve disappeared when viewed through a small or medium sized telescope.

For larger telescopes, it’s easier to see Saturn has a thin multiple ring system. The rings are made of chunks of rock and ice — some just tiny pieces of dust, some more than half a mile (one km) across. Observing Saturn at opposition is important because it will give you an opportunity to witness the Seeliger Effect. Only at opposition will you notice a distinct brightening of the ring system caused by backscattering of sunlight off the icy particles. While we’re “lined up”, keep an eye out for this unusual property as well as the shadow of the rings on the planet and the shadow of the planet on the rings.

And don’t forget those moons… Titan is easy visible to even small telescopes!

February 22, 2008December 26, 2015 by Fraser Cain

Milky Way is Twice as Thick as Previously Believed

Imagine suddenly realizing that your house was twice as big as you originally thought. Okay, maybe that’s a little out there, but astronomers from Australia have calculated that the Milky Way is actually twice as thick as previously believed – doubling from the originally estimated 6,000 light-years to 12,000 light-years.

The calculation was made by a couple of astronomers from the University of Sydney. They were working with the accepted numbers for the dimensions of our home galaxy (6,000 light years thick, and 100,000 light-years wide) when they thought it might make sense to double check those basic assumptions.

They used an accepted technique for calculating distance; measuring the light from pulsars. When light from distant pulsars moves through the background material of the Milky Way (known as the Warm Ionised Medium), it slows down. The redder pulses of light actually slow down more than the bluer pulses.

By measuring the change in light from the pulsar, astronomers can determine how much material the light has traveled through.

When they used the old calculations for 40 different pulsars inside and above it, they got the old numbers. But when they just looked at 17 pulsars which are above and below the galactic disk they got a new, more accurate, estimate.

“Of the thousands of pulsars known in and around our Galaxy, only about 60 have really well known distances,” said Professor Bryan Gaensler. “But to measure the thickness of the Milky Way we need to focus only on those that are sitting above or below the main part of the Galaxy; it turns out that pulsars embedded in the main disk of the Milky Way don’t give us useful information.”

Their results were presented in January at the annual meeting of the American Astronomical Society in Austin, Texas. Some of Dr. Gaensler’s colleagues appreciated the revised calculations, while others… not so pleased at the implications for their own research.

Original Source: University of Sydney

February 22, 2008December 26, 2015 by Fraser Cain

Send in Your Eclipse Pictures, Tell Your Stories

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How was your view of this week’s lunar eclipse? The skies actually opened up here in Vancouver, and we were able to see good portions of the eclipse. The kids were really excited, and got to stay up late watching the eclipse – it was all they were talking about the next day.

So send me your eclipse pictures, and I’ll run a quick gallery. Email them to me at [email protected], and I’ll try to post them in the next few days.

And to tide you over, here’s an image captured by ESA astronomers from Spain.

Post your eclipse stories in the comments below.

February 22, 2008December 29, 2015 by Fraser Cain

Carnival of Space #42

It’s time for another look around the space/astronomy community of websites. This week, the Carnival of Space is being hosted by celebrity blogger, Chris Lintott. Check this week’s collection of stories, including, the search for dark matter, the end of an important observatory, and a good long look at some of Saturn’s moons.

Click here to read the Carnival of Space #42

And if you’re interested in looking back, here’s an archive to all the past carnivals of space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, let me know if you can be a host, and I’ll schedule you into the calendar.

Finally, if you run a space-related blog, please post a link to the Carnival of Space. Help us get the word out.