Astronomy Archives

July 16, 2009December 24, 2015 by Anne Minard

The Eagle Has … Arrived

Eagle Nebula, courtesy of the European Southern Observatory

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We’re still a few days out from the 40th anniversary of the touchdown of Apollo 11’s lunar lander, the Eagle. (The launch went off 40 years and just an hour or so ago.)

Presumably to hold us over, the European Southern Observatory (ESO) has released this stunning new image of the Eagle Nebula.

Located 7000 light-years away, towards the constellation of Serpens (the Snake), the Eagle Nebula is a dazzling stellar nursery, a region of gas and dust where young stars are currently being formed and where a cluster of massive, hot stars, NGC 6611, has just been born. The powerful light and strong winds from these massive new arrivals are shaping light-year long pillars, seen in the image partly silhouetted against the bright background of the nebula. The nebula itself has a shape vaguely reminiscent of an eagle, with the central pillars being the “talons.”

The star cluster was discovered by the Swiss astronomer Jean Philippe Loys de Chéseaux in 1745–46. It was independently rediscovered about 20 years later by the French comet hunter Charles Messier, who included it as number 16 in his famous catalogue and remarked that the stars were surrounded by a faint glow. The Eagle Nebula achieved iconic status in 1995, when its central pillars were depicted in this stunning image obtained with the NASA/ESA Hubble Space Telescope.

The newly released image, obtained with the Wide-Field Imager camera attached to the MPG/ESO 2.2-meter telescope at La Silla, Chile, covers an area on the sky as large as the full Moon, and is more than 200 times more extensive than the iconic Hubble visible-light image. The whole region around the pillars can now be seen in exquisite detail.

The “Pillars of Creation” are in the middle of the image, with the cluster of young stars, NGC 6611, lying above and to the right. The “Spire” — another pillar captured by Hubble — is at the center left of the image.

Finger-like features protrude from the vast cloud wall of cold gas and dust, not unlike stalagmites rising from the floor of a cave. Inside the pillars, the gas is dense enough to collapse under its own weight, forming young stars. These light-year long columns of gas and dust are being simultaneously sculpted, illuminated and destroyed by the intense ultraviolet light from massive stars in NGC 6611, the adjacent young stellar cluster. Within a few million years — a mere blink of the universal eye — they will be gone forever.

Source: ESO. More videos there allow you to zoom in on the Eagle Nebula, pan across it, or cross-fade into several views — all while listening to music that is quite ethereal.

July 15, 2009December 24, 2015 by Anne Minard

Mercury’s Craters Get Artsy New Names

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The MESSENGER mission has been revealing more of Mercury’s surface, including plenty of craters so interesting that geologists have been christening them with names.

The International Astronomical Union released new names for 16 impact craters this week. All of the craters were discovered during the flyby in October, which is also when MESSENGER snapped these images–five minutes apart–as it left.

The IAU has been the arbiter of planetary and satellite nomenclature since its inception in 1919. In keeping with the established naming theme for craters on Mercury, all of the craters are named after famous deceased artists, musicians, or authors. The newly named craters include:

Abedin, after Zainul Abedin, a Bangladeshi painter and printmaker who first attracted attention with his sketches of the Bengal famine of 1943.

Benoit, after Rigaud Benoit, an early member of the Haïtian art movement known as Naive Art, so-called because of its members’ limited formal training.

Berkel, after Sabri Berkel, a Turkish painter and printmaker.

Calvino, after Italo Calvino, an Italian writer of short stories and novels.

de Graft, after Joe Coleman De Graft, a prominent Ghanaian writer, playwright, and dramatist who was appointed the first director of the Ghana Drama Studio in 1962.

Derain, after Andre Derain, a French painter and co-founder of the Fauvism movement with Henri Matisse.

Eastman, after Charles A. Eastman, a Native American (Sioux) author, physician, and reformer who helped found the Boy Scouts of America.

Gibran, after Kahlil (Khalil) Gibran, a Lebanese American artist, poet, and writer, best known for his 1923 book The Prophet, a series of philosophical essays written in English prose.

Hemingway, after Ernest Hemingway, an American writer and journalist who had a significant influence on the development of 20^th century fiction.

Hodgkins, after Frances Hodgkins, a New Zealander painter.

Izquierdo, after María Izquierdo, a Mexican painter who used the landscape and traditions of Mexico as inspirations for her artwork.

Kunisada, after Utagawa Kunisada, a Japanese woodblock printmaker considered the most popular, prolific, and financially successful designer of ukiyo-e woodblock prints in 19^th century Japan.

Lange, after Dorothea Lange, an influential American documentary photographer and photojournalist, best known for her depression-era work for the Farm Security Administration

Matabei, after Iwasa Matabei, a Japanese artist who specialized in genre scenes of historical events and illustrations of classical Chinese and Japanese literature, as well as portraits.

Munkácsy, after Mihály Munkácsy, a Hungarian painter who lived in Paris and earned international reputation with his genre pictures and large-scale biblical paintings

Ngoc Van, a master in Vietnamese oil painting whose painting style was influenced by the French impressionist, Gauguin

Some of the names were suggested by MESSENGER team members, some were suggested by members of the public, and others were selected from a list of names that the IAU had previously approved for use on Mercury.

“Exploring new landforms on Mercury is a special experience that should be shared by everyone on our planet,” says MESSENGER Principal Investigator Sean Solomon of the Carnegie Institution of Washington. “It is highly appropriate that the naming of such features similarly acknowledges the contributions that individuals from all cultures have made to mankind’s advances.”

More information about the names of features on Mercury and the other objects in the Solar System can be found at the U.S. Geological Survey’s Planetary Nomenclature Web site.

The addition of these craters, along with the 27 features previously named, brings the total to 43 newly named surface features on Mercury since MESSENGER’s first flyby of the innermost planet. In September 2009 MESSENGER will complete a third and final flyby of Mercury before becoming the first spacecraft to orbit the planet, beginning in March 2011.

Lead image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington. A portion of the same sequence, totaling 198 images in all, has also been made into a movie.

Source: MESSENGER

July 10, 2009December 24, 2015 by Tammy Plotner

Weekend SkyWatcher’s Forecast: July 10-12, 2009

Greetings, fellow SkyWatchers! Did you happen to see the close appearance of the Moon and Jupiter last night? If you thought that was fun, they’re about to get a whole lot closer tonight – and have company! With a bit darker skies this weekend, it looks like a good time to go globular and explore a few of the summer’s finest. But what weekend would be complete without a little treat? I have one in mind just for you. Follow me…

Friday, July 10, 2009 – If you’re out when the Moon rises, look for the asteroid Psyche nearly brushing the limb 0.2 degrees north. You’ll find the pairing of Jupiter and Neptune about a degree and a half apart and a little more than a finger-width south!

Today we celebrate the 1832 birth on this date of Alvan Graham Clark. An astronomer himself, Clark was also a member of a famous American family of telescope makers. He helped to create the largest refractor in the world—the lenses for the 4000 Yerkes Telescope. Perhaps the stress of worrying for their safety took its toll on Alvan, for he died shortly after their first use.

Before the Moon rises tonight, let’s honor Clark’s work by studying a globular cluster suitable for all optics, M4. All you have to know is Antares! Just slightly more than a degree west (RA 16 23 35 Dec –26 31 31), this major 5th magnitude Class IX globular cluster can even be spotted unaided from a dark location. In 1746 Philippe Loys de Cheseaux happened upon this 7,200-light-year-distant beauty, one of the nearest to us. It was also included in Lacaille’s catalog as object I.9 and in Messier’s in 1764. Much to Charles’s credit, he was the first to resolve it!

As one of the loosest, or most ‘‘open’’ globular clusters, M4 would be tremendous if we were not looking at it through a heavy cloud of interstellar dust. To binoculars, it is easy to pick out a very round, diffuse patch, yet it will begin to resolve with even a small telescope. Large telescopes will also easily see a central ‘‘bar’’ of stellar concentration across M4’s core region, which was first noted by Herschel. As an object of scientific study, in 1987, the first millisecond pulsar was discovered within M4, which turned out to be ten times faster than the Crab Nebula pulsar. Photographed by the Hubble Space Telescope in 1995, M4 was found to contain white dwarf stars—the oldest in our galaxy—with a planet orbiting one of them! A little more than twice the size of Jupiter, this planet is believed to be as old as the cluster itself. At 13 billion years, it would be three times the age of the Solar System!

Saturday, July 11, 2009 – Today marks the 1732 birth on this date of Joseph Jerome Le Francais de Lalande, who determined the Moon’s parallax and published a comprehensive star catalog in 1801.

Tonight let’s head on out toward two more giants that appear differently from the rest (and each other) – same-field binocular pair M10 and M12. Located about half a fist-width west of Beta Ophiuchi, M12 (RA 16 47 14 Dec –01 56 52) is the northern most of this pair. Easily seen as two hazy round spots in binoculars, let’s go to the telescope to find out what makes M12 tick.

Since this large globular is much more loosely concentrated, smaller scopes will begin to resolve individual stars from this 24,000-light-year-distant Class IX cluster. Note that there is a slight concentration toward the core region, but for the most part the cluster appears fairly even. Large instruments will resolve out individual chains and knots of stars.

Now let’s drop about 3.5 degrees southeast and check out Class VII M10 (RA 16 57 08 Dec –04 05 57). What a difference in structure! Although they seem to be close together and similar in size, the pair is actually separated by some 2,000 light-years. M10 is a much more concentrated globular, showing a brighter core region to even the most modest of instruments. This compression of stars is what differentiates one type of globular cluster from another and is the basis of their classification. M10 appears brighter, not because of this compression but because it is about 2,000 light-years closer than M12!

Sunday, July 12, 2009 – Today marks the 1682 passing of Jean Picard. No, not he of Star Trek fame but the Jesuit astronomer who created a movable-wire micrometer to measure the diameters of celestial objects such as the Sun, Moon, and planets!

For hard-core observers, tonight’s globular cluster study will require at least a mid-aperture telescope, because we’re staying up a bit later to go for a same-low-power-field pair—NGC 6522 (RA 18 03 34 Dec –30 02 02) and NGC 6528 (RA 18 04 49 Dec –30 03 20). You will find them easily at low power just a breath northwest of Gamma Sagittarii, better known as Al Nasl, the tip of the ‘‘teapot’s’’ spout.

Once located, switch to higher power to keep the light of Gamma out of the field, and let’s do some study. The brighter, and slightly larger, of the pair to the northeast is Class VI NGC 6522. Note its level of concentration compared to the Class V NGC 6528. Both are located around 2,000 light years away from the galactic center and are seen through a very special area of the sky known as ‘‘Baade’s Window’’—one of the few areas toward our galaxy’s core region not obscured by dark dust. Although each is similar in concentration, distance, etc., NGC 6522 has a slight amount of resolution toward its edges, while NGC 6528 appears more random.

Although both NGC 6522 and NGC 6528 were discovered by Herschel on July 24, 1784, and both are the same distance from the galactic core, they are very different. NGC 6522 has an intermediate metallicity. At its core, the red giants have been depleted, or stripped tidally by evolving into blue stragglers. It is possible that core collapse has already occurred. NGC 6528, however, contains one of the highest metal contents of any known globular cluster collected in its bulging core!

Before you go, why not travel to Lupus and discover Theta, about a fist-width south-southwest of the mighty Antares (RA 16 06 35 Dec –36 48 08). Although this rather ordinary looking 4th magnitude star appears to be nothing special, there’s a lesson to be learned here. So often in our quest to look at the bright and incredible—the distant and impressive—we often forget about the beauty of a single star. When you take the time to seek the path less traveled, you just might find more than you expected. Hiding behind a veil of ‘‘ordinariness’’ is a trio of three spectral types and three magnitudes in a diamond-dust field. An undiscovered gem…

Until next week? Enjoy your beautiful starry nights when you have them. Before you turn down a chance to watch a waning July moonrise… think of how many July moon rises you may have left. Savor each moment and delight in all that’s around you. The rewards are stellar!

This week’s awesome images are (in order of appearance): Alvan Clark with Yerkes objective (historical image), M4, M12, M10, NGC 6522, NGC 6528 and Theta Lupi (credit—Palomar Observatory, courtesy of Caltech). We thank you!

July 10, 2009December 24, 2015 by Nancy Atkinson

Herschel Telescope First Light Images Released

SPIRE images of galaxy M74 at three different infrared wavelengths. Credits: ESA and the SPIRE Consortium

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The Herschel telescope has now turned on all its instruments, taking a few “first light” images with each instrument of galaxies, star-forming regions and dying stars. Herschel astronomers said they were “staggered” by the results, saying “these observations show that Herschel’s instruments are working beyond expectations. They promise a mission of rich discoveries for waiting astronomers.” Above are images taken with Herschel’s Spectral and Photometric Imaging Receiver (SPIRE, of two galaxies, M66 and M74. The galaxies showed up prominently, providing astronomers with their best images yet at these wavelengths. And what’s that in the background? Other more distant galaxies!

Here are three images of M74 taken in three different wavelengths, and of special note is the image taken at 250 microns. This is longer than any previous infrared space observatory. Herschel’s primary mirror is 3.5 m in diameter, nearly four times larger than any previous infrared space telescope. So, expect more dazzling imagery and science to come.

Water in Cygnus

DR21 from the HIFI instrument. Credits: ESA and the HIFI Consortium

Scientists used Herschel’s Heterodyne Instrument for the Far-Infrared (HIFI) to look for warm molecular gas heated by newborn massive stars in the DR21 star-forming region in Cygnus. They were able to observe ionized carbon, carbon monoxide, and water in this region.

HIFI provided excellent data in two different observing modes, returning information on the composition of the region with unprecedented accuracy and resolution. It works by ‘zooming in’ on specific wavelengths, revealing different spectral ‘lines’ that represent the fingerprints of atoms and molecules and even the physical conditions of the object observed. This makes it a powerful tool to study the role of gas and dust in the formation of stars and planets and the evolution of galaxies.

PACS stares into the Cat’s Eye

This panel shows an overlay of individual spectra of the nitrogen line, all taken simultaneously with the PACS spectrometer, on the dust continuum as observed with the PACS photometer. Credits: ESA and the PACS Consortium

The first observation with the Photodetector Array Camera and Spectrometer (PACS) instrument shows the Cat’s Eye Nebula; a complex shell of gas thrown off by a dying star. Dying stars create spectacular nebulae, enriching the interstellar medium with heavy chemical elements. But how does an initially spherical star produce such a complex nebula? Further observations with PACS should help answer questions like that. This instrument makes it possible, for the first time, to take images in spectral lines and see how the wind from the star shapes the nebula in three dimensions.
PACS observed the nebula in two spectral lines from ionized nitrogen and oxygen. It also obtained a small map of the Cat’s Eye Nebula in the 70 micron band, revealing the structure of a dust ring with an opening on one side.

The Herschel instruments will now be tested and calibrated, and the official mission should start around the end of November. “These images demonstrate that there is a lot of science to look forward to,” the scientists said.

Sources: ESA, Herschel Twitter

July 9, 2009December 24, 2015 by Fraser Cain

Have Humans Visited Mercury?

The MESSENGER spacecraft at Mercury (NASA)

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Have astronauts from Earth ever stepped foot on Mercury? No, Mercury has been visited by spacecraft from Earth, but no human has ever gone into orbit around Mercury, let alone stepped on the surface. Just what would it take to visit Mercury?

Humans attempting to visit Mercury would find a similar environment to the Moon. Mercury is airless, so they would need a spacesuit to protect themselves from the vacuum of space. However, the temperatures on Mercury are much greater. During the daytime, the surface of Mercury at the equator rises to 700 Kelvin (427 degrees C). Just for comparison, the surface of the Moon only rises to 390 Kelvin (117 degrees C) during the daytime. So you would need some kind of protection from the intense heat.

But then, nighttime on Mercury dips down to only 100 Kelvin (-173 degrees C) – that’s the same low temperatures you get on the Moon at night. So an astronaut’s spacesuit would need to be able to keep an astronaut warm when they’re in the shade.

The travel time to the Moon is only about 3 days. But the travel time to Mercury is much longer. That’s partly because Mercury is much further away – 10s of millions km. But spacecraft also need to take special trajectories so they can get into orbit around Mercury. All of the spacecraft that have visited Mercury have taken longer than a year to reach the planet. That would be a long, hot journey for astronauts.

Maybe some day in the future humans will visit Mercury, but it hasn’t happened yet.

We have written many stories about Mercury here on Universe Today. Here’s an article about a the discovery that Mercury’s core is liquid. And how Mercury is actually less like the Moon than previously believed.

Want more information on Mercury? Here’s a link to NASA’s MESSENGER Misson Page, and here’s NASA’s Solar System Exploration Guide to Mercury.

We have also recorded a whole episode of Astronomy Cast that’s just about planet Mercury. Listen to it here, Episode 49: Mercury.

Reference:
NASA Star Child: Mercury

July 9, 2009December 24, 2015 by Fraser Cain

Geology of Mercury

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The geology of Mercury is similar to the geology of the Moon; although, Mercury is a much denser planet with a larger liquid iron core. But when you look at photographs of Mercury, it really looks like you’re looking at the Moon. The surface of Mercury is covered by impact craters and lava plains.

Planetary scientists can judge the age of a planet’s surface by the number and size of impact craters. In the case of Mercury, there are enough craters that scientists think that the surface of Mercury is largely unchanged for billions of years. It’s believed that the surface of Mercury is geologically inactive; although, only 55% of the surface has been mapped in enough detail to see its geology.

Mercury formed with the rest of the Solar System about 4.6 billion years ago. After that was a period of heavy bombardment by asteroids and comets; this lasted until 3.8 billion years ago. All of the planets in the Solar System were beaten up during the Late Heavy Bombardment period, but we can still see the scars on Mercury and the Moon. Some of the largest craters in this period were filled with lava from Mercury’s interior. It’s believed that vulcanism on Mercury ended during its first 700 800 million years.

Craters on Mercury can be small bowl-shaped pockets, or huge impact craters hundreds of kilometers across. The largest crater on Mercury is the Caloris Basin, measuring 1,550 km across. There have been about 15 large impact basins identified on Mercury. Just like the Moon, the larger craters have bright rays of material; it’s brighter because it hasn’t been as weathered by impacts.

One of the unique places on Mercury are the regions around its poles. Astronomers using radar telescopes have detected large deposits of water ice around Mercury’s poles. It’s believed these deposits of ice are located in deep craters near Mercury’s poles where they’re always in shadow. It’s possible these were deposited by comet impacts billions of years ago.

Want more information on Mercury? Here’s a link to NASA’s MESSENGER Misson Page, and here’s NASA’s Solar System Exploration Guide to Mercury.

We have also recorded a whole episode of Astronomy Cast that’s just about planet Mercury. Listen to it here, Episode 49: Mercury.

References:
NASA Solar System Exploration: Mercury
NASA: The Solar System’s Big Bang

July 9, 2009December 24, 2015 by Brian Ventrudo

Solved: Mystery of Gamma Ray Distribution in the Milky Way

A team of astrophysicists has solved the mystery of the distribution of gamma rays in our Milky Way galaxy. While some researchers thought the distribution suggested a form of undetectable “dark matter”, the team from the University of California, San Diego, proposed an explanation based on standard physical models of the galaxy.

In two separate scientific papers, the most recent of which appears in the July 10 issue of the journal Physical Review Letters, the astrophysicists show that this distribution of gamma rays can be explained by the way “antimatter positrons” from the radioactive decay of elements, created by massive star explosions in the galaxy, propagate through the galaxy. That means, the scientists said, the observed distribution of gamma rays is not evidence for dark matter.

“There is no great mystery,” said Richard Lingenfelter, a research scientist at UC San Diego’s Center for Astrophysics and Space Sciences who conducted the studies with Richard Rothschild, a research scientist also at UCSD, and James Higdon, a physics professor at the Claremont Colleges. “The observed distribution of gamma rays is in fact quite consistent with the standard picture.”

Over the past five years, gamma ray measurements from the European satellite INTEGRAL have perplexed astronomers, leading some to argue that a “great mystery” existed because the distribution of these gamma rays across different parts of the Milky Way galaxy was not as expected.

To explain the source of this mystery, some astronomers had hypothesized the existence of various forms of dark matter, which astronomers suspect exists—from the unusual gravitational effects on visible matter such as stars and galaxies—but have not yet found.

What is known for certain is that our galaxy—and others—are filled with tiny subatomic particles known as positrons, the antimatter counterpart of typical, everyday electrons. When an electron and positron encounter each other in space, the two particles annihilate and their energy is released as gamma rays. That is, the electron and positron disappear and two or three gamma rays appear.

”These positrons are born at nearly the speed of light, and travel thousands of light years before they slow down enough in dense clouds of gas to have a chance of joining with an electron to annihilate in a dance of death,” explains Higdon. “Their slowing down occurs from the drag of other particles during their journey through space. Their journey is also impeded by the many fluctuations in the galactic magnetic field that scatter them back and forth as they move along. All of this must be taken into account in calculating the average distance the positrons would travel from their birthplaces in supernova explosions.”

”Some positrons head towards the center of the Galaxy, some towards the outer reaches of the Milky Way known as the galactic halo, and some are caught in the spiral arms,” said Rothschild. “While calculating this in detail is still far beyond the fastest supercomputers, we were able to use what we know about how electrons travel throughout the solar system and what can be inferred about their travel elsewhere to estimate how their anti-matter counterparts permeate the galaxy.”

The scientists calculated that most of the gamma rays should be concentrated in the inner regions of the galaxy, just as was observed by the satellite data, the team reported in a paper published last month in the Astrophysical Journal.

“The observed distribution of gamma rays is consistent with the standard picture where the source of positrons is the radioactive decay of isotopes of nickel, titanium and aluminum produced in supernova explosions of stars more massive than the Sun,” said Rothschild.

In their companion paper in this week’s issue of Physical Review Letters, the scientists point out that a basic assumption of one of the more exotic explanations for the purported mystery—dark matter decays or annihilations—is flawed, because it assumes that the positrons annihilate very close to the exploding stars from which they originated.

“We clearly demonstrated this was not the case, and that the distribution of the gamma rays observed by the gamma ray satellite was not a detection or indication of a ‘dark matter signal’,” said Lingenfelter.

Source: UC San Diego

July 9, 2009December 24, 2015 by Anne Minard

Earliest Stars Came in Pairs, New Simulation Shows

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Most stars exist in binary pairs today — and new research indicates that may have been true for a very long time. This simulation of a primordial star forming region about 200 million years after the Big Bang shows two pre-stellar cores of more than five times the mass of the sun each. The cores formed at a separation of 800 times the distance from the Earth to the Sun, and are expected to evolve into a binary star system.

Most previous simulations of the early universe, in which clouds of primordial gas collapsed to form the first luminous objects, suggest that early stars formed separately from each other.

Lead author Matthew Turk, of Stanford University, and his colleagues performed computer simulations during which a central clump of primordial material about 50 times the mass of the Sun breaks into two cores with a mass ratio of two to one. Both are able to cool and plump up, by accreting matter from the surrounding cold gas reservoir, “and will likely form a binary star system,” the authors write.

The findings may also have implications for detecting both gravity waves — disturbances predicted by general relativity, which haven’t yet been detected directly — and the ultra-energetic explosions known as gamma ray bursts, since binary systems are thought to be at the origins of both of these phenomena.

The results are in this week’s issue of the journal Science and appear online today at the Science Express website.

Source: Science, via Eurekalert.

July 8, 2009April 26, 2016 by Nancy Atkinson

New Technique Finds Farthest Supernovae

This artist’s impression of a supernova shows the layers of gas ejected prior to the final deathly explosion of a massive star. Credit: NASA/Swift/Skyworks Digital/Dana Berry

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Two of the farthest supernovae ever detected have been found by using a new technique that could help find other dying stars at the edge of the universe. The two cosmic blasts occurred 11 billion years ago. The next-farthest large supernova known occurred about 6 billion years ago. Jeff Cooke from the University of California Irvine said this new method has the potential to allow astronomers to study some of the very first supernovae and will advance the understanding of how galaxies form, how they change over time and how Earth came to be.

A supernova occurs when a massive star (more than eight times the mass of the sun) dies in a powerful, bright explosion. Cooke studies larger stars (50 to 100 times the mass of the sun) that blow part of their mass into their surroundings before they die. When they finally explode, the nearby matter glows brightly for years.

Typically, cosmologists find supernovae by comparing pictures taken at different times of the same swath of sky and looking for changes. Any new light could indicate a supernova.

Cooke built upon this idea. He blended pictures taken over the course of a year, then compared them with image compilations from other years.

“If you stack all of those images into one big pile, then you can reach deeper and see fainter objects,” Cooke said. “It’s like in photography when you open the shutter for a long time. You’ll collect more light with a longer exposure.”

This image shows the host galaxy containing one of the newly discovered supernovae. Comparing the images shows how the galaxy visibly brightens in 2004 and then returns to normal. This suggested that in 2003 the supernova was not detected; it appeared in 2004 and was beginning to fade in 2005. The last frame subtracts the images from the years that the supernova was not detected as well as the galaxy’s light to reveal only the supernova. Credit: Jeff Cooke/CFHT

Doing this with images from the Cooke found four objects that appeared to be supernovae. He used a Keck telescope to look more closely at the spectrum of light each object emitted and confirmed they were indeed supernovae.

“The universe is about 13.7 billion years old, so really we are seeing some of the first stars ever formed,” Cooke said.

Cooke’s paper is published in the journal Nature on July 9.

Source: UC-Irvine

July 7, 2009December 24, 2015 by Abby Cessna

Discovery of the Planets

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We actually only know the exact date of when a few of the planets were discovered. Five of the planets, not including Earth, have been known to exist for thousands of years – Mercury, Mars, Venus, Jupiter, and Saturn. The Ancient Greeks and Romans wrote about the planets many centuries ago. Because the planets look like stars to the naked eye, that is where the term planets comes from. Because the planets move in the sky, they were termed wandering stars. The term planet comes from the Greek word for wanderer, “planetes.” Many ancient people thought that the planets were gods, so they gave them the names of their gods. All of the planets, except Earth have names of Roman deities.

The other three planets – Uranus, Neptune, and Pluto – were not discovered until at least the 1700’s. Pluto is no longer a planet since it was reclassified as a dwarf planet in 2006. It was known as the ninth planet for 70 years though, so its discovery will be included here. Uranus was discovered in 1781 by the famous astronomer Sir William Herschel, although that was not the first sighting of it. The planet had been sighted as early as 1690 by the English astronomer John Flamsteed. It was also sighted by Pierre Lemonier in the mid 1700’s. Sir Herschel at first thought that Uranus was a comet, but he noticed the irregularities early on and compared it to a planet in his notes.

Because Neptune cannot be seen without the help of a telescope, it was not discovered until after 1610, when Galileo created the telescope. Alexis Bouvard, a mathematician, saw that another planet had to be affecting Uranus’ orbit, so astronomers started looking for it. Two astronomers, John Couch Adams and Urbain Le Verrier, discovered Neptune independently or rather made the calculations and determined where Neptune could be found. The planet turned out to be 1° from Verrier’s calculations and 12° from Adams’. There was a dispute between France and England over who discovered the new planet because Adams and Verrier are from England and France respectively.

Pluto was the last planet discovered, although that distinction returned to Neptune when Pluto was reclassified as a dwarf planet. Pluto was discovered in 1930 by the astronomer Clyde Tombaugh. Many people had been searching for a ninth planet – the elusive planet X – for quite a while. Since Pluto was discovered near the calculated location of planet X, they thought the two planets were one and the same. Later, astronomers realized that there was no such planet X.

Universe Today has a number of articles on the planets including who discovered Neptune and the planets of our Solar System.

Check out these other articles including mathematical discovery of the planets and the planets.

Astronomy Cast has episodes on all of the planets including Mercury.