Thursday, May 7, 2015

100,000 Galaxies, and No Obvious Signs of Life

100,000 Galaxies, and No Obvious Signs of Life:



This is a false-color image of the mid-infrared emission from the Great Galaxy in Andromeda, as seen by Nasa's WISE space telescope. The orange color represents emission from the heat of stars forming in the galaxy's spiral arms. The G-HAT team used images such as these to search 100,000 nearby galaxies for unusually large amounts of this mid-infrared emission that might arise from alien civilizations. Credit: NASA/JPL-Caltech/WISE Team


False-color image of the mid-infrared emission from the Great Galaxy in Andromeda, as seen by Nasa’s WISE space telescope. Credit: NASA/JPL-Caltech/WISE Team
Beam us up, Scotty. There’s no signs of intelligent life out there. At least, no obvious signs, according to a recent survey performed by researchers at Penn State University. After reviewing data taken by the NASA Wide-field Infrared Survey Explorer (WISE) space telescope of over 100,000 galaxies, there appears to be little evidence that advanced, spacefaring civilizations exist in any of them.

First deployed in 2009, the WISE mission has been able to identify thousands of asteroids in our solar system and previously undiscovered star clusters in our galaxy. However, Jason T. Wright, an assistant professor of astronomy and astrophysics at the Center for Exoplanets and Habitable Worlds at Penn State University, conceived of and initiated a new field of research – using the infrared data to assist in the search for signs of extra-terrestrial civilizations.

And while their first look did not yield much in the way of results, it is an exciting new area of research and provides some very useful information on one of the greatest questions ever asked: are we alone in the universe?

“The idea behind our research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization’s technologies would be detectable in mid-infrared wavelengths,” said Wright, “exactly the radiation that the WISE satellite was designed to detect for other astronomical purposes.”

This logic is in keeping with the theories of Russian astronomer Nikolai Kardashev and theoretical physicist Freeman Dyson. In 1964, Kardashev proposed that a civilization’s level of technological advancement could be measured based on the amount of energy that civilization is able to utilize.



Freemon Dyson theorized that eventually, a civilization would be able to build a megastructure around its star to capture all its energy. Credit: SentientDevelopments.com


Freemon Dyson theorized that eventually, a civilization would be able to enclose its star with a megastructure that would to capture and utilize its energy. Credit: sentientdevelopments.com
To characterize the level of extra-terrestrial development, Kardashev developed a three category system – Type I, II, and III civilizations –  known as the “Kardashev Scale”. A Type I civilization uses all available resources on its home planet, while a Type II is able to harness all the energy of its star. Type III civilizations are those that are advanced enough to harness the energy of their entire galaxy.

Similarly, Dyson proposed in 1960 that advanced alien civilizations beyond Earth could be detected by the telltale evidence of their mid-infrared emissions. Believing that a sufficiently advanced civilization would be able to enclose their parent star, he believed it would be possible to search for extraterrestrials by looking for large objects radiating in the infrared range of the electromagnetic spectrum.

These thoughts were expressed in a short paper submitted to the journal Science, entitled “Search for Artificial Stellar Sources of Infrared Radiation“. In it, Dyson proposed that an advanced species would use artificial structures – now referred to as “Dyson Spheres” (though he used the term “shell” in his paper) – to intercept electromagnetic radiation with wavelengths from visible light downwards and radiating waste heat outwards as infrared radiation.

“Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy’s stars to power computers, space flight, communication, or something we can’t yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths,” said Wright. “This same basic physics causes your computer to radiate heat while it is turned on.”



Wide-field Infrared Survey Explorer, or WISE, will scan the entire sky in infrared light, picking up the glow of hundreds of millions of objects and producing millions of images


The Wide-field Infrared Survey Explorer (WISE) scans the entire sky in infrared light, picking up the glow of hundreds of millions of objects and producing millions of images. Credit: NASA/JPL-Caltech
However, it was not until space-based telescopes like WISE were deployed that it became possible to make sensitive measurements of this radiation. WISE is one of three infrared missions currently in space, the other two being NASA’s Spitzer Space Telescope and the Herschel Space Observatory – a European Space Agency mission with important NASA participation.

WISE is different from these missions in that it surveys the entire sky and is designed to cast a net wide enough to catch all sorts of previously unseen cosmic interests. And there are few things more interesting than the prospect of advanced alien civilizations!

To search for them, Roger Griffith – a postbaccalaureate researcher at Penn State and the lead author of the paper – and colleagues scoured the entries in the WISE satellites database looking for evidence of a galaxy that was emitting too much mid-infrared radiation. He and his team then individually examined and categorized 100,000 of the most promising galaxy images.

And while they didn’t find any obvious signs of a Type II civilization or Dyson Spheres in any of them, they did find around 50 candidates that showed unusually high levels of mid-infrared radiation. The next step will be to confirm whether or not these signs are due to natural astronomical processes, or could be an indication of a highly advanced civilization tapping their parent star for energy.



WISE will find the most luminous galaxies in the universe -- incredibly energetic objects bursting with new stars. The infrared telescope can see the glow of dust that shrouds these galaxies, hiding them from visible-light telescopes. An example of a dusty, luminous galaxy is shown here in this infrared portrait of the "Cigar" galaxy taken by NASA's Spitzer Space Telescope. Dust is color-coded red, and starlight blue. Credit: NASA/JPL-Caltech/Steward Observatory


WISE will take images of the most luminous galaxies in the universe, such as the “Cigar” galaxy shown here – taken by NASA’s Spitzer Space Telescope. Credit: NASA/JPL-Caltech/Steward Observatory
In any case, the team’s findings were quite interesting and broke new ground in what is sure to be an ongoing area of research. The only previous study, according to the G-HAT team, surveyed only about 100 galaxies, and was unable to examine them in the infrared to see how much heat they emitted. What’s more, the research may help shed some light on the burning questions about the very existence of intelligent, extra-terrestrial life in our universe.

“Our results mean that, out of the 100,000 galaxies that WISE could see in sufficient detail, none of them is widely populated by an alien civilization using most of the starlight in its galaxy for its own purposes,” said Wright. “That’s interesting because these galaxies are billions of years old, which should have been plenty of time for them to have been filled with alien civilizations, if they exist. Either they don’t exist, or they don’t yet use enough energy for us to recognize them.”

Alas, it seems we are no closer to resolving the Fermi Paradox. But for the first time, it seems that investigations into the matter are moving beyond theoretical arguments. And given time, and further refinements in our detection methods, who knows what we might find lurking out there? The universe is very, very big place, after all.

The research team’s first research paper about their Glimpsing Heat from Alien Technologies Survey (G-HAT) survey appeared in the Astrophysical Journal Supplement Series on April 15, 2015.

Further Reading: Astrophysical Journal via EurekAlert, JPL-NASA



About 

Author, freelance writer, educator, Taekwon-Do instructor, and loving hubby, son and Island boy!

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The 2015 Lyrid Meteors Peak Tomorrow Night!

The 2015 Lyrid Meteors Peak Tomorrow Night!:



A lucky capture of a 2013 Lyrid meteor. Image credit and copyright: John Chumack


A lucky capture of a 2013 Lyrid meteor. Image credit and copyright: John Chumack
April showers bring May flowers, and this month also brings a shower of the celestial variety, as the Lyrid meteors peak this week.

And the good news is, 2015 should be a favorable year for the first major meteor shower of the Spring season for the northern hemisphere.  The peak for the shower in 2015 is predicted to arrive just after midnight Universal Time on Thursday April 23rd, which is 8:00 PM EDT on the evening of Wednesday April 22nd. This favors European longitudes right around the key time, though North America could be in for a decent show as well. Remember, meteor showers don’t read forecasts, and the actual peak can always arrive early or late. We plan to start watching tonight and into Wednesday and Thursday morning as well. April also sees a extremely variable level of cloud cover over the northern hemisphere, another reason to start your meteor vigil early on if skies are clear.



The radiant for the 2015 Lyrids as seen from 40 degrees north latitude at local midnight. Credit: Stellarium.


The radiant for the 2015 Lyrids as seen from 40 degrees north latitude at local midnight. Credit: Stellarium.
Another favorable factor this year is the phase of the Moon, which is only a slender 20% illuminated waxing crescent on Wednesday night. This means that it will have set well before local midnight when the action begins.

The source of the Lyrid meteors is Comet C/1861 G1 Thatcher, which is on a 415 year orbit and is expected to come back around again in 2276 A.D. 1861 actually sported two great comets, the other being C/1861 J1, also known as the Great Comet of 1861.



The orientation of the Sun, Moon, and the Lyrid radiant at the expected peak of the shower at 24UT/20EDT April 22nd. credit: Stellarium


The orientation of the Sun, Moon, and the Lyrid radiant at the expected peak of the shower at 24UT/20EDT April 22nd. credit: Stellarium
The Lyrids typically exhibit an ideal Zenithal Hourly Rate (ZHR) of 15-20 per hour, though this shower has been known to produce moderate outbursts from time to time. In 1803 and 1922, the Lyrids produced a ZHR of 100 per hour, and in recent times, we had an outburst of 250 per hour back in 1982. Researchers have tried over the years to tease out a periodicity for Lyrid outbursts, which seem erratic at best. In recent years, the Lyrids hit a ZHR of 20 (2011), 25 (2012), 22 (2013), and 16 last year in 2014.

Keep in mind, we say that the ZHR is an ideal rate, or what you could expect from the meteor shower with the radiant directly overhead under dark skies: expect the actual number of meteors observed during any shower to be significantly less.



A 2014 Lyrid fireball. Credit: The UK Meteor Network


A 2014 Lyrid fireball. Credit: The UK Meteor Network
The radiant for the Lyrids actually sits a few degrees east of the bright star Vega across the Lyra border in the constellation Hercules. They should, in fact, be named the Herculids! In mid-April, the radiant for the April Lyrids has already risen well above the northeastern horizon as seen from latitude 40 degrees north at 10 PM local, and is roughly overhead by 4 AM local. Several other minor showers are also active around late April, including the Pi Puppids (April 24th), the Eta Aquarids (May 6th), and the Eta Lyrids (May 9th). The constellation of the Lyre also lends its name to the June Lyrids peaking around June 6th.

The April Lyrids are intersecting the Earth’s orbit at a high 80 degree angle at a swift velocity of 49 kilometres per second. About a quarter of the Lyrid meteors are fireballs, leaving bright, persistent smoke trains. It’s a good idea to keep a set of binoculars handy to study these lingering smoke trails post-passage.



The Lyrids also have the distinction of having the longest recorded history of any known meteor shower.  Chinese chronicles indicate that “stars dropped down like rain,” on a late Spring night in 687 BC.

Observing a meteor shower requires nothing more than a set of working ‘Mark-1 eyeballs’ and patience. The International Meteor Organization always welcomes reports of meteor counts from observers worldwide to build an accurate picture of evolving meteor debris streams. You can even hear meteor ‘pings’ via FM radio.

Expect the rate to pick up past local midnight, as the Earth plows headlong into the oncoming meteor stream. Remember, the front of the car gets the love bugs, an apt analogy for any Florida resident in mid-April.



A composite view of the 2012 Lyrids plus sporadic meteors. Credit: NASA/MSFC/Danielle Moser


A composite view of the 2012 Lyrids plus sporadic meteors. Credit: NASA/MSFC/Danielle Moser
Catching a photograph of a Lyrid or any meteor is as simple as plopping a DSLR down on a tripod and doing a series of 30 second to several minute long time exposures. Use the widest field of view possible, and aim the camera off at about a 45 degree angle from the radiant to catch the meteors sidelong in profile. Be sure to take a series of test shots to get the ISO/f-stop combination set for the local sky conditions.

Don’t miss the 2015 Lyrids, possibly the first good meteor shower of the year!



About 

David Dickinson is an Earth science teacher, freelance science writer, retired USAF veteran & backyard astronomer. He currently writes and ponders the universe from Tampa Bay, Florida.

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Hubble Telescope Celebrates 25 Years in Space With Spectacular New Image

Hubble Telescope Celebrates 25 Years in Space With Spectacular New Image:



This NASA/ESA Hubble Space Telescope image of the cluster Westerlund 2 and its surroundings has been released to celebrate Hubble’s 25th year in orbit and a quarter of a century of new discoveries, stunning images and outstanding science. Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), and the Westerlund 2 Science Team. Click the image for access to larger versions.


This NASA/ESA Hubble Space Telescope image of the cluster Westerlund 2 and its surroundings has been released to celebrate Hubble’s 25th year in orbit and a quarter of a century of new discoveries, stunning images and outstanding science. Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), and the Westerlund 2 Science Team. Click the image for access to larger versions.
Images from space don’t get any prettier than this. A new image from the Hubble Space Telescope was released today to commemorate a quarter century of exploring the Solar System and beyond since the launch of the telescope on April 24, 1990. It shows a giant cluster of about 3,000 stars called Westerlund 2, located 20,000 light-years away from Earth in the constellation Carina. NASA describes the new image as a “brilliant tapestry of young stars flaring to life resemble a glittering fireworks display.”

The Hubble Teams are giving away a few “gifts” to everyone to celebrate this silver anniversary — see below!


“Hubble has completely transformed our view of the universe, revealing the true beauty and richness of the cosmos” said John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate. “This vista of starry fireworks and glowing gas is a fitting image for our celebration of 25 years of amazing Hubble science.”

The cluster is named after Swedish astronomer Bengt Westerlund who discovered the grouping in the 1960s.

You can get access to larger versions of the image here at ESA’s Hubble website, or at NASA’s HubbleSite.

There are anniversary events occurring around the US and the world. Here is a listing of at the Hubble anniversary site, where people can also find science articles, educational resources, downloadable presentations, and more:

And here’s a downloadable 25th anniversary gift for everyone: Hubble is offering a free ebook of 25 of Hubble’s most significant images, which can be found at this link or at iTunes.

See a stunning gallery of all the ‘anniversary’ images that have been released by the Hubble teams over the last 25 years at this Flickr gallery.

And finally, here’s an excellent visualization of a flight to the star cluster Westerlund 2:




About 

Nancy Atkinson is currently Universe Today's Contributing Editor. Previously she served as UT's Senior Editor and lead writer, and has worked with Astronomy Cast and 365 Days of Astronomy. Nancy is also a NASA/JPL Solar System Ambassador.

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Watch an Enormous “Plasma Snake” Erupt from the Sun

Watch an Enormous “Plasma Snake” Erupt from the Sun:



SOHO LASCO C2 (top) and SDO AIA 304 (bottom) image of a solar filament detaching on April 28-29, 2015


SOHO LASCO C2 (top) and SDO AIA 304 (bottom) image of a solar filament detaching on April 28-29, 2015
Over the course of April 28–29 a gigantic filament, briefly suspended above the surface* of the Sun, broke off and created an enormous snakelike eruption of plasma that extended millions of miles out into space. The event was both powerful and beautiful, another demonstration of the incredible energy and activity of our home star…and it was all captured on camera by two of our finest Sun-watching spacecraft.

Watch a video of the event below.



Made from data acquired by both NASA’s Solar Dynamics Observatory (SDO) and the joint ESA/NASA SOHO spacecraft, the video was compiled by astronomer and sungrazing comet specialist Karl Battams. It shows views of the huge filament before and after detaching from the Sun, and gives a sense of the enormous scale of the event.

At one point the plasma eruption spanned a distance over 33 times farther than the Moon is from Earth!

Filaments are long channels of solar material contained by magnetic fields that have risen up from within the Sun. They are relatively cooler than the visible face of the Sun behind them so they appear dark when silhouetted against it; when seen rising from the Sun’s limb they look bright and are called prominences.

When the magnetic field lines break apart, much of the material contained within the filaments gets flung out into space (a.k.a. a CME) while some gets pulled back down into the Sun. These events are fairly common but that doesn’t make them any less spectacular!

Also read: Watch the Sun Split Apart

This same particularly long filament has also been featured as the Astronomy Picture of the Day (APOD), in a photo captured on April 27 by Göran Strand.

For more solar news follow Karl Battams on Twitter.

Image credits: ESA/NASA/SOHO & SDO/NASA and the AIA science team.

*The Sun, being a mass of incandescent gas, doesn’t have a “surface” like rocky planets do so in this case we’re referring to its photosphere and chromosphere.



About 

A graphic designer in Rhode Island, Jason writes about space exploration on his blog Lights In The Dark, Discovery News, and, of course, here on Universe Today. Ad astra!

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Gravitational Anomalies of Mercury

Gravitational Anomalies of Mercury: APOD: 2015 May 5 - Gravitational Anomalies of Mercury


Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 May 5



See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: What's that under the surface of Mercury? The robotic MESSENGER spacecraft that had been orbiting planet Mercury for the past four years had been transmitting its data back to Earth with radio waves of very precise energy. The planet's gravity, however, slightly changed this energy when measured on Earth, which enabled the reconstruction of a gravity map of unprecedented precision. Here gravitational anomalies are shown in false-color, superposed on an image of the planet's cratered surface. Red hues indicate areas of slightly higher gravity, which in turn indicates areas that must have unusually dense matter under the surface. The central area is Caloris Basin, a huge impact feature measuring about 1,500 kilometers across. Last week, after completing its mission and running low on fuel, MESSENGER was purposely crashed onto Mercury's surface.

Tuesday, May 5, 2015

An Unexpected Aurora over Norway

An Unexpected Aurora over Norway: APOD: 2015 May 4 - An Unexpected Aurora over Norway


Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 May 4


See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: Sometimes the sky lights up unexpectedly. A trip to northern Norway to photograph auroras was not going as well as hoped. It was now past midnight in Steinsvik, Troms, in northern Norway, and the date was 2014 February 8. Despite recent activity on the Sun, the skies were disappointing. Therefore, the astrophotographer began packing up to go. His brother began searching for a missing lens cap. When the sky suddenly exploded with spectacular aurora. Reacting quickly, a sequence detailing dramatic green curtains was captured, with the bright Moon near the image center, and the lens-cap seeking brother on the far right. The auroral flare lasted only a few minutes, but the memory of this event, the photographer speculates, will last much longer.

Sunday, May 3, 2015

Blue Tears and the Milky Way

Blue Tears and the Milky Way: APOD: 2015 April 24 - Blue Tears and the Milky Way


Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 April 24


See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: Lapping at rocks along the shore of the Island of Nangan, Taiwan, planet Earth, waves are infused with a subtle blue light in this sea and night skyscape. Composed of a series of long exposures made on April 16 the image captures the faint glow from Noctiluca scintillans. Also known as sea sparkles or blue tears, the marine plankton's bioluminescence is stimulated by wave motion. City lights along the coast of mainland China shine beneath low clouds in the west but stars and the faint Milky Way still fill the night above. Over the horizon the galaxy's central bulge and dark rifts seem to echo the rocks and luminous waves.

Cluster and Starforming Region Westerlund 2

Cluster and Starforming Region Westerlund 2: APOD: 2015 April 25 - Cluster and Starforming Region Westerlund 2


Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 April 25


See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: Located 20,000 light-years away in the constellation Carina, the young cluster and starforming region Westerlund 2 fills this cosmic scene. Captured with Hubble's cameras in near-infrared and visible light, the stunning image is a celebration of the 25th anniversary of the launch of the Hubble Space Telescope on April 24, 1990. The cluster's dense concentration of luminous, massive stars is about 10 light-years across. Strong winds and radiation from those massive young stars have sculpted and shaped the region's gas and dust, into starforming pillars that point back to the central cluster. Red dots surrounding the bright stars are the cluster's faint newborn stars, still within their natal gas and dust cocoons. But brighter blue stars scattered around are likely not in the Westerlund 2 cluster and instead lie in the foreground of the Hubble anniversary field of view.

Planetary Nebula Mz3: The Ant Nebula

Planetary Nebula Mz3: The Ant Nebula: APOD: 2015 April 26 - Planetary Nebula Mz3: The Ant Nebula


Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 April 26


See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: Why isn't this ant a big sphere? Planetary nebula Mz3 is being cast off by a star similar to our Sun that is, surely, round. Why then would the gas that is streaming away create an ant-shaped nebula that is distinctly not round? Clues might include the high 1000-kilometer per second speed of the expelled gas, the light-year long length of the structure, and the magnetism of the star visible above at the nebula's center. One possible answer is that Mz3 is hiding a second, dimmer star that orbits close in to the bright star. A competing hypothesis holds that the central star's own spin and magnetic field are channeling the gas. Since the central star appears to be so similar to our own Sun, astronomers hope that increased understanding of the history of this giant space ant can provide useful insight into the likely future of our own Sun and Earth.

Massive Nearby Spiral Galaxy NGC 2841

Massive Nearby Spiral Galaxy NGC 2841: APOD: 2015 April 28 - Massive Nearby Spiral Galaxy NGC 2841


Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 April 28


See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: It is one of the more massive galaxies known. A mere 46 million light-years distant, spiral galaxy NGC 2841 can be found in the northern constellation of Ursa Major. This sharp view of the gorgeous island universe shows off a striking yellow nucleus and galactic disk. Dust lanes, small, pink star-forming regions, and young blue star clusters are embedded in the patchy, tightly wound spiral arms. In contrast, many other spirals exhibit grand, sweeping arms with large star-forming regions. NGC 2841 has a diameter of over 150,000 light-years, even larger than our own Milky Way and captured by this composite image merging exposures from the orbiting 2.4-meter Hubble Space Telescope and the ground-based 8.2-meter Subaru Telescope. X-ray images suggest that resulting winds and stellar explosions create plumes of hot gas extending into a halo around NGC 2841.

Across the Sun

Across the Sun: APOD: 2015 April 30 - Across the Sun


Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 April 30


See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: A long solar filament stretches across the relatively calm surface of the Sun in this telescopic snap shot from April 27. The negative or inverted narrowband image was made in the light of ionized hydrogen atoms. Seen at the upper left, the magnificent curtain of magnetized plasma towers above surface and actually reaches beyond the Sun's edge. How long is the solar filament? About as long as the distance from Earth to Moon, illustrated by the scale insert at the left. Tracking toward the right across the solar disk a day later the long filament erupted, lifting away from the Sun's surface. Monitored by Sun staring satellites, a coronal mass ejection was also blasted from the site but is expected to swing wide of our fair planet.

M51: The Whirlpool Galaxy

M51: The Whirlpool Galaxy: APOD: 2015 May 2 - M51: The Whirlpool Galaxy


Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 May 2



See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: Follow the handle of the Big Dipper away from the dipper's bowl until you get to the handle's last bright star. Then, just slide your telescope a little south and west and you might find this stunning pair of interacting galaxies, the 51st entry in Charles Messier famous catalog. Perhaps the original spiral nebula, the large galaxy with well defined spiral structure is also cataloged as NGC 5194. Its spiral arms and dust lanes clearly sweep in front of its companion galaxy (right), NGC 5195. The pair are about 31 million light-years distant and officially lie within the angular boundaries of the small constellation Canes Venatici. Though M51 looks faint and fuzzy to the eye, deep images like this one can reveal striking colors and the faint tidal debris around the smaller galaxy