The ISS and Endeavour transitting the sun. Credit: Thierry Legault
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Wow! Take a look at this image captured by award-winning French astrophotographer Thierry Legault. The visible detail of the shuttle and parts of the International Space Stations is absolutely amazing! If you remember, Legault also took images of space shuttle Atlantis and the Hubble Space Telescope transiting the sun back in May during the HST servicing mission.
Legault is an engineer who lives near Paris. He started his digital imaging in 1994, and currently uses a SBIG STL-11000M CCD camera with AO-L system that is equipped with large and narrow band filters. He also uses a reflex Canon 5D, webcams from Philips as well as Astrovid video cameras.
The Opportunity Rover picture that never happened (sadly!) Credit: Stuart Atkinson
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This week’s Astro Art of the Week is one of my favorite creations from my pal Stuart Atkinson, and it is a picture that never happened. Oh, the Opportunity rover did take a picture of its crumpled backshell on the surface of Mars, as seen above. But look closer: Stuart has added a reflection of the rover in the shiny metal — a self-portrait that could have been taken had the rover come close enough. Stuart writes on his blog Cumbrian Skies:
“My favourite “picture that never was” is a self-portrait of Oppy that she could… possibly… perhaps… maybe… have taken as she rolled around the edge of Endurance Crater, some 350 days after landing on Mars. How cool would that have been?!?! A picture of a Mars rover taken BY a Mars rover! Okay, so it would have been a bit distorted, and blurry, but still, what a picture it would have been. A killer image to be sure. I remember thinking at the time “Go on, take the picture, it’ll be amazing! It’ll be EVERYWHERE!”, and being very frustrated and disappointed when they didn’t.
“But I can understand why they didn’t risk it. If I was in charge of a mega-expensive Mars rover, just 350 days into its mission, I wouldn’t have been too keen to drive it into a veritable minefield of bits of metal that could have got stuck in its wheels, snagged cables or worse. No, they absolutely did the right thing. But still… all these years later I can’t help wondering what that picture would have turned out like… Maybe something like this…”
Thanks Stu, for sharing your image!
And remember, we’re still looking for a good name for this new feature of using space or astronomy images created with digital image editing software, so submit suggestions in the comments. And if you like to fool around with image editing, consider submitting one of your own. Submit them to Nancy here.
Ice loss in Barrow Alaska from 2006 to 2007. Credit: US Geological Survey
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Last week the US government released more than a thousand intelligence images of Arctic ice that have been used to help scientists study the impact of climate change. The images were taken by spy satellites, as part of the Medea program, which lets scientists request spy pictures from environmentally sensitive locations around the world. After they were taken, the Bush Administration released the photographs to the scientists but deemed them “unsuitable for public release.” Earlier this month, the National Academy of Sciences recommended the Obama Administration declassify the photos, which they did within a few hours of the recommendation.
Various blogs are saying these dramatic images are faked, but since they are available through the US Geological Survey , that hardly seems likely. Over 700 images show changes of sea ice in various recent years from six sites around the Arctic Ocean, with an additional 500 images of 22 sites in the United States.
Ice loss in the Beaufort Sea. Credit: USGS
Scientists request ice pictures to be taken by intelligence satellites because the resolution is much greater, in some cases, than other available satellite images. According to Reuters, the newly declassified Arctic images have a resolution of about 1 yard (1 meter), a vast improvement on previously available pictures of sea ice which have a resolution between 15 and 30 meters. Ice loss at the Bering Glacier. Credit: USGS
The newly discovered Green Pea galaxies. (Photo: Carolin Cardamone and Sloan Digital Sky Survey.)
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Citizen scientists from the Galaxy Zoo project have discovered rare galaxies they’re calling the “Green Peas.” They’re small in size, bright green in color, and proficient at churning out new stars — plus, they could reveal unique insights into how galaxies form stars in the early universe.
The newly discovered galaxies appear in the image at left, from Carolin Cardamone and the Sloan Digital Sky Survey.
“These are among the most extremely active star-forming galaxies we’ve ever found,” said Cardamone, an astronomy graduate student at Yale University and lead author of a new paper on the discovery. The results will appear in an upcoming issue of the Monthly Notices of the Royal Astronomical Society.
Galaxy Zoo users volunteer their spare time to help classify galaxies in an online image bank. Cardamone said of the one million galaxies that make up Galaxy Zoo’s image bank, the team found only 250 Green Peas.
“No one person could have done this on their own,” she said. “Even if we had managed to look through 10,000 of these images, we would have only come across a few Green Peas and wouldn’t have recognized them as a unique class of galaxies.”
The Green Peas boast “some of the highest specific star formation rates seen in the local Universe,” write Cardamone and her co-authors, “yielding doubling times for their stellar mass of hundreds of millions of years.”
The authors say evidence points to recent or ongoing mergers, adding that the Peas are similar in size, mass, luminosity and metallicity to Luminous Blue Compact Galaxies.
“They are also similar to high redshift UV-luminous galaxies, e.g., Lyman-break galaxies and Lyman-alpha emitters, and therefore provide a local laboratory with which to study the extreme star formation processes that occur in high-redshift galaxies,” they write.
The galaxies, which are between 1.5 billion and 5 billion light years away, are 10 times smaller than our own Milky Way galaxy and 100 times less massive. But they are forming stars 10 times faster than the Milky Way.
Kevin Schawinski, a postdoctoral associate at Yale and one of Galaxy Zoo’s founders, said the Green Peas would have been normal in the early universe, “but we just don’t see such active galaxies today. Understanding the Green Peas may tell us something about how stars were formed in the early universe and how galaxies evolve.”
The Galaxy Zoo volunteers who discovered the Green Peas—and who call themselves the “Peas Corps” and the “Peas Brigade”—began discussing the strange objects in the online forum. (The original forum thread was called “Give peas a chance.”)
Cardamone asked the volunteers, many of whom had no previous astronomy background or experience, to refine the sample of objects they detected in order to determine which were bona fide Green Peas and which were not, based on their colors. By analyzing their light, Cardamone determined how much star formation is taking place within the galaxies.
“This is a genuine citizen science project, where the users were directly involved in the analysis,” Schawinski said, adding that 10 Galaxy Zoo volunteers are acknowledged in the paper as having made a particularly significant contribution. “It’s a great example of how a new way of doing science produced a result that wouldn’t have been possible otherwise.”
Trojan asteroids sharing the orbits of Jupiter and Neptune. Image credit: Scott Sheppard.
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A planetesimal is an object formed from dust, rock, and other materials. The word has its roots in the concept infinitesimal, which indicates an object too small to see or measure. Planetesimals can be anywhere in size from several meters to hundreds of kilometers. The term refers to small celestial bodies formed during the creation of planets. One way to think of them is as small planets, but they are much more than that.
The planetesimal theory was suggested by the Russian astronomer Viktor Safronov. The planetesimal theory is a theory on how planets form. According to the planetesimal hypothesis, when a planetary system is forming, there is a protoplanetary disk with materials from the nebulae from which the system came. This material is gradually pulled together by gravity to form small chunks. These chunks get larger and larger until they form planetesimals. Many of the objects break apart when they collide, but some continue to grow. Some of these planetesimals go on to become planets and moons. Since the gas giants are balls of gas with liquid cores, it may seem impossible that an asteroid-like object formed them. The planetesimals formed the core of these gaseous planets, which turned molten when it enough heat was created.
Other planetesimals turn into comets, Kuiper Belt Objects (KBOs), and trojan asteroids. There is some debate as to whether KBOs and asteroids can be called planetesimals. This is one reason why nomenclature of celestial objects is so difficult. The planetesimal theory is not universally accepted though. Like many theories, there are some observations that cannot be explained, but the planetesimal theory is still very popular.
Many people think that around 3.8 billion years ago, many of the planetesimals were thrown into far away regions, such as the Oort cloud or the Kuiper Belt. Other objects collided with other objects after being affected by gas giants. Phobos and Deimos are believed to be planetesimals that were captured by Mars’ gravity and became satellites. Many of Jupiter’s moons are believed to be planetesimals as well.
Planetesimals are very valuable to scientists because they can provide information about the creation of our Solar System. The exterior of planetesimals have been bombarded with solar radiation, which can change their chemistry, for billions of years. Inside though, there is material that has been untouched since the object was first formed. Using this material, astronomers hope to learn about the condition of the nebulae from which our Solar System was formed.
The symbols of the eight planets, and Pluto, Credit: insightastrology.net
In our long history of staring up at the stars, human beings have assigned various qualities, names, and symbols for all the objects they have found there. Determined to find patterns in the heavens that might shed light on life here on Earth, many of these designations ascribed behavior to the celestial bodies.
When it comes to assigning signs to the planets, astrologists and astronomers – which were entwined disciplines in the past -made sure that these particular symbols were linked to the planets’ names or their history in some way.
Consider the planet Mercury, named after the Roman god who was himself the messenger of the gods, noted for his speed and swiftness. The name was assigned to this body largely because it is the planet closest to the Sun, and which therefore has the fastest rotation period. Hence, the symbol is meant to represent Mercury’s helmet and caduceus – a herald’s staff with snakes and wings intertwined.
Mercury, as imaged by the MESSENGER spacecraft, which was named after the messenger of the gods because it has the fastest orbit around the Sun. Image Credit: NASA/JHU/Carnegie Institution.
Venus:
Venus’ symbol has more than one meaning. Not only is it the sign for “female”, but it also represents the goddess Venus’ hand mirror. This representation of femininity makes sense considering Venus was the goddess of love and beauty. The symbol is also the chemical sign for copper; since copper was used to make mirrors in ancient times.
Earth:
Earth’s sign also has a variety of meanings, although it does not refer to a mythological god. The most popular view is that the circle with a cross in the middle represents the four main compass points. It has also been interpreted as the Globus Cruciger, an old Christian symbol for Christ’s reign on Earth.
This symbol is not just limited to Christianity though, and has been used in various culture around the world. These include, but are not limited to, Norse mythology (where it appears as the Solar or Odin’s Cross), Native American cultures (where it typically represented the four spirits of direction and the four sacred elements), the Celtic Cross, the Greek Cross, and the Egyptian Ankh.
In fact, perhaps owing to the simplicity of the design, cross-shaped incisions have made appearances as petroglyphs in European cult caves dating all the way back to the beginning of the Upper Paleolithic, and throughout prehistory to the Iron Age.
Mars, as photographed with the Mars Global Surveyor, is identified with the Roman god of war. Credit: NASA
Mars:
Mars is named after the Roman god of war, owing perhaps to the planet’s reddish hue, which gives it the color of blood. For this reason, the symbol associated with Mars represents the god of wars’ shield and spear. Additionally, it is the same sign as the one used to represent “male”, and hence is associated with self-assertion, aggression, sexuality, energy, strength, ambition and impulsiveness.
Jupiter:
Jupiter’s sign, which looks like an ornate, oddly shaped “four,” also stands for a number of symbols. It has been said to represent an eagle, which is Jupiter’s bird. Additionally, the symbol can stand for a “Z,” which is the first letter of Zeus – who was Jupiter’s Greek counterpart.
The line through the symbol is consistent with this, since it would indicate that it was an abbreviation for Zeus’ name. And last, but not least, there is the addition of the swirled line which is believed to represent a lighting bolt – which just happens to Jupiter’s (and Zeus’) weapon of choice.
Saturn:
Like Jupiter, Saturn resembles another recognizable character – this time, it’s an “h.” However, this symbol is actually supposed to represent Saturn’s scythe or sickle, because Saturn is named after the Roman god of agriculture.
Jupiter, the largest planet in the Solar System, is appropriately named after the Roman father of the gods. Credit: NASA/ESA/A. Simon (Goddard Space Flight Center)
Uranus:
The sign for Uranus is a combination of two other signs – Mars’ sign and the symbol of the Sun – because the planet is connected to these two in mythology. Uranus represented heaven in Roman mythology, and this ancient civilization believed that the Sun’s light and Mars’ power ruled the heavens.
Neptune:
Neptune’s sign is linked to the sea god Neptune, who the planet was named after. Appropriately, the symbol represents this planet is in the shape of the sea god’s trident.
Pluto:
Although Pluto was demoted to a dwarf planet, it still has a symbol. Pluto’s sign is a combination of a “P” and a “L,” which are the first two letters in Pluto as well as the initials of Percival Lowell, the astronomer who discovered the planet.
Other Objects:
The Moon is represented by a crescent shape, which is a clear allusion to how the Moon appears in the night sky more often than not. Since the Moon is also tied to people’s perceptions, moods, and emotional make-up, the symbol has also come to represents the mind’s receptivity.
A full moon captured July 18, 2008. Credit: NASA/Sean Smith
And then there’s the sun, which is represented by a circle with a dot in the middle. In the case of the Sun, this symbol represents the divine spirit (circle) surrounding the seed of potential, which is a direct association with ancient Sun worship and the central role Sun god’s played in ancient pantheons.
The planets have played an important role in the culture and astrological systems of every human culture. Because of this, the symbols, names, and terms that denote them continue to hold special significance in our hearts and minds.
Take a look at the Solar System from above, and you can see that the planets make nice circular orbits around the Sun. But dwarf planet’s Pluto’s orbit is very different. It’s highly elliptical, traveling around the Sun in a squashed circle. And Pluto’s orbit is highly inclined, traveling at an angle of 17-degrees. This strange orbit gives Pluto some unusual characteristics, sometimes bringing it within the orbit of Neptune. Credit: NASA
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Centuries ago, people believed that the Earth was the center of the Solar System. Slowly, that view was replaced with the heliocentric view. With that change came the realization that the planets orbit the Sun.
When Pluto was reclassified as a dwarf planet, Mercury became the planet with the most eccentric orbit. The eccentricity of an orbit is a measurement of how much the orbit deviates from a circular shape. If an orbit is a perfect circle, it has an eccentricity of zero, and that number increases with an increase in eccentricity. Mercury has an eccentricity of .21. Its orbit ranges from 46 million kilometers at the closest point to the Sun to 70 million kilometers at the farthest point. The closest point to the Sun in an orbit is called the perihelion, and the farthest point is the aphelion. Mercury is the fastest planet to orbit the Sun at approximately Earth 88 days.
Venus has the least eccentricity of any planet in our Solar System – eccentricity of .007 – with a nearly perfect circular orbit. Venus’ orbit ranges from 107 million kilometers at the perihelion to 109 million kilometers from the Sun. It takes 224.7 of our days to orbit the Sun. A day on Venus is actually longer than a year because the planet rotates so slowly. Seen from the Sun’s north pole, all of the planets rotate counter-clockwise, but Venus actually rotates clockwise; it is the only planet to do that.
Earth also has a very low eccentricity of .017. On average, the planet is about 150 million kilometers from the Sun, but it can range from 147 million kilometers to 152 million kilometers. It takes our planet roughly 365.256 days to orbit the Sun, which is the reason for leap years.
Mars has an eccentricity of .093 making it one of the most eccentric orbits in our Solar System. Mars perihelion is 207 million kilometers and its aphelion is 249 million kilometers from the Sun. Over time, Mars’ orbit has become more eccentric. It takes 687 Earth days to orbit the Sun.
Jupiter has an eccentricity of .048 with a perihelion of 741 million kilometers and an aphelion of 778 million kilometers. It takes 4331 Earth days – 11.86 of our years – for Jupiter to orbit the Sun.
Saturn has an eccentricity of .056. At its closest point, Saturn is 1.35 billion kilometers from the Sun, and 1.51 billion kilometers away at its farthest point. Depending on what position it is in its orbit, Saturn’s rings are fully visible or almost invisible. The planet takes 29.7 years to orbit the Sun. In fact, since it was discovered in 1610, Saturn has only orbited approximately 13 times. Earth has orbited the Sun almost 400 times since then.
Uranus has a perihelion of 2.75 billion kilometers and an aphelion of 3 billion kilometers from the Sun. Its eccentricity is .047. It takes Uranus 84.3 Earth years to orbit the Sun. Uranus is unique because it actually rotates on its side with an axial tilt of almost 99°.
Neptune’s eccentricity is .009, almost as low as Venus’. The planet has a perihelion of 4.45 billion kilometers and an aphelion of 4.55 billion kilometers. Since Pluto was reclassified as a dwarf planet, Neptune is the planet with an orbit farthest from the Sun.
Universe Today has articles on orbits of all the planets including Mercury and Mars.
It is often difficult to grasp just how large the planets actually are. There are a number of ways to measure a planet, including diameter, volume, and surface area.
Mercury is the smallest planet in our Solar System since Pluto was demoted to a dwarf planet. It has a diameter of 4,879 km, and a surface area of 17.48 x 107 km2, which is only about 11% of Earth’s surface area. Mercury’s volume is even smaller in comparison at 6.083 x 1010 km3, which is only 5.4% the volume of Earth.
Venus is similar in size to Earth, which earned it the title of Earth’s twin. Venus has a diameter of 12,100 km and a surface area of 4.6 x 108 km2. These measurements are 95% and 90% of Earth’s diameter and surface area respectively. With a volume of 9.38 x 1011 km3, Venus’ volume is 86% of Earth’s.
Earth has a diameter of 12,742 km and a surface area of 5.1 x 108 km2. Its volume of 1.08 x 1012 km3 gives the planet the largest volume of any of the terrestrial planets.
Mars is also a small planet, the second smallest in our Solar System. Mars’ diameter is 6,792 km, only about 53% of Earth’s diameter. At only 28% of Earth’s surface area, Mars has a very small surface area of 1.45 x 108 km2. Mars’ volume of 1.63 x 1011 km3 is only 15% of Earth’s volume.
All of the gas giants are larger in size than the four inner planets. Jupiter is the largest planet in our Solar System. It has a diameter of 143,000 km, which is more than 11 times the size of Earth’s diameter. The numbers only get larger from there. Jupiter has a surface area of 6.22 x 1010 km2. That is 122 times greater than Earth’s surface area. Jupiter’s volume of 1.43 x 1015 km3 is an incredible number. You can fit 1321 Earths inside Jupiter.
Saturn is the second largest planet in our Solar System. It has a diameter of 120,536 km across the equator, and a surface area of 4.27 x 1010 km2. With a volume of 8.27 x 1014 km3, Saturn can hold 764 Earths inside.
Uranus has a diameter of 51,118 km and a surface area of 8.1 x 109 km2. Although Uranus is much smaller than Jupiter, it is still large. With a volume of 6.83 x 1013 km3, you could fit 63 Earths inside the gas giant.
Neptune is slightly smaller than Uranus, but still very large. The planet has a diameter of 49,500 km. You could fit 57.7 Earths inside Neptune, which has a volume of 6.25 x1013 km3. Neptune has a surface area of 7.64 x 109 km2, which is 15 times Earth’s surface area.
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 Fraser know if you can be a host, and he’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.
Are you ready to stay up a little late and see if you can catch the new dark spot on Jupiter from what could have either been an asteroid or comet impact? It happened somewhere between July 17th and 19th and the scar is still fresh and visible. However, there is just a little bit you need to know to make your viewing the Jupiter impact through your telescope a success.
By July 21, Joe Brimacombe was on this phenomena and recording it. Says Joe: “Got very lucky: CBET 1882 just announced a transient new black spot on Jupiter’s south polar region that it a probable comet impact. By chance I’d been imaging Jupiter between gaps in the clouds and seem to have captured it just before it rotated out of view. Seeing conditions were above average for Cairns.”
And he did a video for us:
Of course, Jupiter and its surface features are one of the easiest targets for backyard telescopes – so seeing something that large – and dark against a light background – should be easy. Right? Wrong. Viewing through our own Earth’s atmosphere plays a huge role on how we see the atmosphere of Jupiter. Low horizon conditions, unsteady or turbulent air, thin clouds, humidity, temperature… all of these are key factors in planetary observing. Observing skills come only with experience, but given the time and effort – you CAN do it!
Before we go out to look for the impact, let’s stop and talk about Jupiter. There’s a reason so many amateurs love to this fast-rotating disk full of dynamic colored features… Because it’s so easy to see changes! Much like our own skin, the chemical composition of Jupiter’s atmosphere “tans” in the sunlight and the continual motion of its banded weather patterns keep an array of festoons, loops, ovals and barges on display at all times. How difficult is it to spot something? Then know this photo frame of a shadow transit is a 100% realistic view taken by me with a very small telescope with my camcorder. No tweaks, no filters… And it was much clearer to the eye than the camera. However, we need to remember that Jupiter rotates completely in about 10 hours, so a feature you see on its meridian at 11:00 pm won’t be there at 3:00 am. Like the “Great Red Spot”, the whole atmosphere is constantly on the move and there’s no guarantee that something that looks great one night will return again on another.
Now, let’s think positively! The impact spot is located near Jupiter’s System II longitude 210°. Although it’s small, if you use a lot of magnification, you should be able to spot it near the pole. The next thing you need to know is when to look! And here are the times the Jupiter impact can be seen for the next 10 days: July 25, 10:54 and 20:49; July 26, 6:45 and 16:41; July 27, 2:36, 12:32 and 22:27; July 28, 8:23 and 18:18; July 29, 4:14, 14:20 and 23:59; July 30, 10:01 and 19:56; July 31, 5:52 and 15:48. For August 1, 01:43, 11:39, 21:34; August 2, 7:32 and 17:25; August 3, 3:23, 13:17 and 23:12; August 4, 9:08 and 19:03; August 5, 4:59 and 14:54; August 6, 0:50, 10:46 and 20:41; August 7, 6:37 and 16:32; August 8, 2:28, 12:24 and 22:18; August 9, 8:15 and 18:20; August 10, 4:06, 14:01, 23:57; August 11, 9:53 and 19:48; August 12, 5:42 and 15:39; August 13, 01:35, 11:31 and 21:26; Auugst 14, 7:22 and 17:17; August 15, 3:13, 13:08, 23:04. Remember, these are very approximate Universal times when it should be visible on the meridian and you should have at least 20-30 minutes of opportunity on either side of the listed time to catch it as it rotates in and out.
Will the impact spot last in the days ahead? Unfortunately, just like the Shoemaker-Levy impact, the atmosphere will shred the debris cloud quickly. It is difficult enough to catch a feature near Jupiter’s poles because of limb darkening – so don’t wait to make your observations. Wishing you clear and steady skies!
Many thanks to Joe Brimacombe of Southern Galactic for sharing his incredible images with us!
