Artist’s conception of the Gaia telescope backdropped by a photograph of the Milky Way taken at the European Southern Observatory. Credit: ESA/ATG medialab; background: ESO/S. Brunier
In 2013, the European Space Agency deployed the long-awaited Gaia space observatory. As one of a handful of next-generation space observatories that will be going up before the end of the decade, this mission has spent the past few years cataloging over a billion astronomical objects. Using this data, astronomers and astrophysicists hope to create the largest and most precise 3D map of the Milky Way to date.
Though it is almost to the end of its mission, much of its earliest information is still bearing fruit. For example, using the mission’s initial data release, a team of astrophysicists from the University of Toronto managed to calculate the speed at which the Sun orbits the Milky Way. From this, they were able to obtain a precise distance estimate between our Sun and the center of the galaxy for the first time.
For some time, astronomers have been unsure as to exactly how far our Solar System is from the center of our galaxy. Much of this has to do with the fact that it is impossible to view it directly, due to a combination of factors (i.e. perspective, the size of our galaxy, and visibility barriers). As a result, since the year 2000, official estimates have varied between 7.2 and 8.8 kiloparsecs (~23,483 to 28,700 light years).
Infrared image from Spitzer Space Telescope, showing the stars at the center of the Milky Way Galaxy. Credit: NASA/JPL-Caltech/S. Stolovy (SSC/Caltech)
For the sake of their study, the team – which was led by Jason Hunt, a Dunlap Fellow at the Dunlap Institute for Astronomy & Astrophysics at the University of Toronto – combined Gaia’s initial release with data from the RAdial Velocity Experiment (RAVE). This survey, which was conducted between 2003 and 2013 by the Australian Astronomical Observatory (AAO), measured the positions, distances, radial velocities and spectra of 500,000 stars.
Over 200,000 of these stars were also observed by Gaia and information on them was included in its initial data release. As they explain in their study, which was published in the Journal of Astrophysical Letters in November 2016, they used this to examined the speeds at which these stars orbit the center of the galaxy (relative to the Sun), and in the process discovered that there was an apparent distribution in their relative velocities.
In short, our Sun moves around the center of the Milky Way at a speed of 240 km/s (149 mi/s), or 864,000 km/h (536,865 mph). Naturally, some of the more than 200,000 candidates were moving faster or slower. But for some, there was no apparent angular momentum, which they attributed to these stars being scattering onto “chaotic, halo-type orbits when they pass through the Galactic nucleus”.
As Hunt explained in Dunlap Institute press release:
“Stars with very close to zero angular momentum would have plunged towards the Galactic center where they would be strongly affected by the extreme gravitational forces present there. This would scatter them into chaotic orbits taking them far above the Galactic plane and away from the Solar neighbourhood… By measuring the velocity with which nearby stars rotate around our Galaxy with respect to the Sun, we can observe a lack of stars with a specific negative relative velocity. And because we know this dip corresponds to 0 km/sec, it tells us, in turn, how fast we are moving.”
Detection of an unusually bright X-Ray flare from Sagittarius A*, a supermassive black hole in the center of the Milky Way galaxy. Credit: NASA/CXC/Stanford/I. Zhuravleva et al.
The next step was to combine this information with proper motion calculations of Sagittarius A* – the supermassive black hole believed to be at the center of our galaxy. After correcting for its motion relative to background objects, they were able to effectively triangulate the Earth’s distance from the center of the galaxy. From this, they derived a refined distance of estimate of 7.6 to 8.2 kpc – which works out to about 24,788 to 26,745 light years.
This study builds upon previous work conducted by the study’s co-authors – Prof. Ray Calberg, the current chair of the Department of Astronomy & Astrophysics at the University of Toronto. Years ago, he and Prof. Kimmo Innanen of the Department of Physics and Astronomy at York University conducted a similar study using radial velocity measurement from 400 of the Milky Way’s stars.
But by incorporating data from the Gaia observatory, the UofT team was able to obtain a much more comprehensive data set and narrow the distance to galactic center by a significant amount. And this was based on only the initial data released by the Gaia mission. Looking ahead, Hunt anticipates that further data releases will allow his team and other astronomers to refine their calculations even more.
“Gaia’s final release in late 2017 should enable us to increase the precision of our measurement of the Sun’s velocity to within approximately one km/sec,” he said, “which in turn will significantly increase the accuracy of our measurement of our distance from the Galactic center.”
As more next-generation space telescopes and observatories are deployed, we can expect them to provide us with a wealth of new information about our Universe. And from this, we can expect that astronomers and astrophysicists will begin to shine the light on a number of unresolved cosmological questions.
There are regular volcanoes, and then there are the supervolcanoes. Massive calderas of hot magma of incomprehensible size. Bad news, these things explode randomly and catastrophically. Worse news, there are a bunch around the Earth.
We usually record Astronomy Cast as a live Google+ Hangout on Air every Friday at 1:30 pm Pacific / 4:30 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.
An impact between a Mars-sized protoplanet and early Earth is the most widely-accepted origin of the Moon. Did smaller impacts seed the formation of continents? (NASA/JPL-Caltech)
For centuries, scientists have been attempting to explain how the Moon formed. Whereas some have argued that it formed from material lost by Earth due to centrifugal force, others asserted that a preformed Moon was captured by Earth’s gravity. In recent decades, the most widely-accepted theory has been the Giant-impact hypothesis, which states that the Moon formed after the Earth was struck by a Mars-sized object (named Theia) 4.5 billion years ago.
According to a new study by an international team of researchers, the key to proving which theory is correct may come from the first nuclear tests conducted here on Earth, some 70 years ago. After examining samples of radioactive glass obtained from the Trinity test site in New Mexico (where the first atomic bomb was detonated), they determined that samples of Moon rocks showed a similar depletion of volatile elements.
First SpaceX Falcon 9 rocket atop Launch Complex 39-A at the Kennedy Space Center comes to life with successful static hot fire test at 430 p.m. on 12 Feb 2017 as seen from Space View Park, Titusville, Fl. This is the first rocket to stand on pad 39A since the retirement of NASA’s Space Shuttles in July 2011. Credit: Ken Kremer/Kenkremer.com
First SpaceX Falcon 9 rocket atop Launch Complex 39-A at the Kennedy Space Center comes to life with successful static hot fire test at 430 p.m. on 12 Feb 2017 as seen from Space View Park, Titusville, Fl. This is the first rocket to stand on pad 39A since the retirement of NASA’s Space Shuttles in July 2011. Credit: Ken Kremer/Kenkremer.com
SPACE VIEW PARK/KENNEDY SPACE CENTER, FL – For the first time in more than half a decade, a rocket came to life at NASA’s Kennedy Space Center when a SpaceX Falcon 9 breathed her first fire at historic pad 39A today, Sunday, Feb. 12 – successfully completing a critical static test firing of the first stage engines that opens the door to a launch to the space station next weekend for NASA.
The hot fire test generated a huge plume of smoke exhausting out the north side of the flame trench of Launch Complex 39A at approximately 4:30 p.m. EST, Feb. 12.
The hold down engine test with the erected rocket involved the ignition of all nine Merlin 1D first stage engines generating some 1.7 million pounds of thrust at pad 39A – which has been repurposed from its days as a shuttle launch pad.
The Merlin 1D engines fired for about 3 seconds while the two stage rocket was restrained on the pad.
SpaceX confirmed the test via social media shortly after it took place.
“First static fire test of Falcon 9 at historic launch complex 39A completed in advance of Dragon’s upcoming mission to the @Space_Station,” SpaceX tweeted in a very brief announcement.
I watched excitedly from a public viewing spot at Space View Park in Titusville as the exhaust plume grew quickly in size to a gigantic grey-white colored mushroom cloud of smoke and ash, heaving out the north side of the flame trench silent since the shuttle era.
Then just as quickly the smoke cloud dissipated completely within about 10 minutes leaving barely a trace of what we can expect to see soon.
Titusville offers a prime viewing location for anyone interested in traveling to the Florida Space Coast to see this Falcon 9 launch in person.
First SpaceX Falcon 9 rocket atop Launch Complex 39A at the Kennedy Space Center comes to life with successful static hot fire test at 430 p.m. on 12 Feb. 2017 as seen from Space View Park, Titusville, Fl. Liftoff is slated for no earlier than 18 Feb. 2017. Credit: Ken Kremer/Kenkremer.com
The test confirms that both the first stage engines and the rocket are suited for liftoff. Over the past few days, launch teams also tested the pad equipment, raised and lowered the rocket and conducted fit checks of the rocket at the pad.
The test had been delayed several days as technicians coped with issues until all was right to carry out the static fire test.
The positive outcome paves the path for a Falcon 9.Dragon blastoff as soon as next Saturday.
This marks the first time any rocket has stood on pad 39A and fired its engines since the retirement of NASA’s Space Shuttles in July 2011 on the STS-135 mission to the space station.
First SpaceX Falcon 9 rocket atop Launch Complex 39A at the Kennedy Space Center comes to life with successful static hot fire test at 430 p.m. on 12 Feb. 2017 as seen from Space View Park, Titusville, Fl. Liftoff is slated for no earlier than 18 Feb. 2017. Credit: Ken Kremer/Kenkremer.com
Liftoff of the Falcon 9 is slated for no earlier than next Saturday, 18 Feb 2017 on a critical cargo flight for NASA to deliver over two and a half tons of science and supplies to the six person crew living and working on the International Space Station (ISS).
The rocket – minus the payload comprising the Dragon cargo spacecraft – was rolled out of the SpaceX processing hangar at the perimeter fence and then up the incline to the top of pad 39A on Friday morning using a dedicated transporter-erector.
First SpaceX Falcon 9 rocket stands erect atop Launch Complex 39-A at the Kennedy Space Center on 10 Feb 2017 as seen from Playalinda Beach, Fl. This is the first rocket to stand on pad 39A since the retirement of NASA’s Space Shuttles in July 2011. Liftoff to the ISS is slated for 18 Feb 2017 on the CRS-10 resupply mission for NASA. Credit: Jeff Seibert/AmericaSpace
After the successful completion of the static fire test, the booster will be rolled back to the big processing hangar and the Dragon resupply ship will be integrated on top.
The historic NASA launch pad was formerly used to launch both America’s space shuttles and astronauts on Apollo/Saturn V moon landing missions.
Dragon will be loaded with more than 5500 pounds of equipment, gear, food, supplies and NASA’s Stratospheric Aerosol Gas Experiment III (SAGE III) ozone mapping science payload.
Engineers at work processing NASA’s Stratospheric Aerosol and Gas Experiment III, or SAGE III instrument inside the Space Station Processing Facility at NASA’s Kennedy Space Center in Florida during exclusive visit by Ken Kremer/Universe Today in December 2016. Technicians are working in a super-clean ‘tent’ built in the SSPF high bay to protect SAGE III’s special optics and process the Ozone mapper for upcoming launch on the SpaceX CRS-10 Dragon cargo flight to the International Space Station in early 2017. Credit: Ken Kremer/kenkremer.com
SpaceX was previously employing pad 40 on Cape Canaveral Air Force Station for Falcon 9 launches to the ISS as well as commercial launches.
But pad 40 suffered severe damage following the unexpected launch pad explosion on Sept 1, 2016 that completely destroyed a Falcon 9 and the $200 million Amos-6 commercial payload during a prelaunch fueling test.
An accident investigation revealed that a second stage helium tank burst due to friction ignition during the fueling test.
SpaceX modified the fueling procedures as a short term fix and is working on redesigning the second stage as a long term fix.
SpaceX is working to repair and refurbish pad 40. It is not known when it will be ready to resume launches.
Thus SpaceX has had to switch launch pads for near term future flights and press pad 39A into service much more urgently, speeding up the refurbishing and repurposing work which at last is sufficient to launch rockets again.
Pad 39A has lain dormant for launches for nearly six years since Space Shuttle Atlantis launched on the final shuttle mission STS 135 in July 2011.
STS-135: Last launch using RS-25 engines that will now power NASA’s SLS deep space exploration rocket. NASA’s 135th and final shuttle mission takes flight on July 8, 2011 at 11:29 a.m. from the Kennedy Space Center in Florida bound for the ISS and the high frontier with Chris Ferguson as Space Shuttle Commander. Credit: Ken Kremer/kenkremer.com
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Up close view of SpaceX Dragon CRS-9 resupply ship and solar panels atop Falcon 9 rocket at pad 40 prior to blastoff to ISS on July 18, 2016 from Cape Canaveral Air Force Station, Florida. Credit: Ken Kremer/kenkremer.com
This composite of 25 images of asteroid 2017 BQ6 was generated with radar data collected using NASA’s Goldstone Solar System Radar in California’s Mojave Desert. It sped by Earth on Feb. 7 at a speed of around 25,560 mph (7.1 km/s) relative to the planet. The images have resolutions as fine as 12 feet (3.75 meters) per pixel. Credit: NASA/JPL-Caltech/GSSR
To radar imager Lance Benner at JPL in Pasadena, asteroid 2017 BQ6 resembles the polygonal dice used in Dungeons and Dragons. But my eyes see something closer to a stepping stone or paver you’d use to build a walkway. However you picture it, this asteroid is more angular than most imaged by radar.
It flew harmlessly by Earth on Feb. 7 at 1:36 a.m. EST (6:36 UT) at about 6.6 times the distance between Earth and the moon or some about 1.6 million miles. Based on 2017 BQ6’s brightness, astronomers estimate the hurtling boulder about 660 feet (200 meters) across. The recent flyby made for a perfect opportunity to bounce radio waves off the object, harvest their echoes and build an image of giant space boulder no one had ever seen close up before.
NASA’s 70-meter antennas are the largest and most sensitive Deep Sky Network antennas, capable of tracking a spacecraft traveling tens of billions of miles from Earth. This one at Goldstone not only tracked Voyager 2’s Neptune encounter, it also received Neil Armstrong’s famous communication from Apollo 11: “That’s one small step for a man. One giant leap for mankind.” Credit: JPL-Caltech/GSSR
The images of the asteroid were obtained on Feb. 6 and 7 with NASA’s 230-foot (70-meter) antenna at the Goldstone Deep Space Communications Complex in California and reveal an irregular, angular-appearing asteroid:
Animation of 2017 BQ6. The near-Earth asteroid has a rotation period of about 3 hours. Credit: NASA/JPL-Caltech/GSSR
“The radar images show relatively sharp corners, flat regions, concavities, and small bright spots that may be boulders,” said Lance Benner of NASA’s Jet Propulsion Laboratory in Pasadena, California, who leads the agency’s asteroid radar research program. “Asteroid 2017 BQ6 reminds me of the dice used when playing Dungeons and Dragons.”
Radar has been used to observe hundreds of asteroids. Even through very large telescopes, 2017 BQ6 would have appeared exactly like a star, but the radar technique reveals shape, size, rotation, roughness and even surface features.
This chart shows how data from NASA’s Wide-field Infrared Survey Explorer, or WISE, has led to revisions in the estimated population of near-Earth asteroids. Credit: NASA/JPL-Caltech
To create the images, Benner conducted a controlled experiment on the asteroid, transmitting a signal with well-known characteristics to the object and then, by comparing the echo to the transmission, deduced its properties. According to NASA’s Asteroid Radar Research site, measuring how the echo power spreads out over time along with changes in its frequency caused by the Doppler Effect (object approaching or receding from Earth), provide the data to construct two-dimensional images with resolutions finer than 33 feet (10 meters) if the echoes are strong enough.
This orbital diagram shows the close approach of 2017 BQ6 to Earth on Feb. 7, 2017. Credit: NASA/JPL Horizons
In late October 2016, the number of known near-Earth asteroids topped 15,000 with new discoveries averaging about 30 a week. A near-Earth asteroid is defined as a rocky body that approaches within approximately 1.3 times Earth’s average distance to the Sun. This distance then brings the asteroid within roughly 30 million miles (50 million km) of Earth’s orbit. To date, astronomers have already discovered more than 90% of the estimated number of the large near-Earth objects or those larger than 0.6 miles (1 km). It’s estimated that more than a million NEAs smaller than 330 feet (100 meters) lurk in the void. Time to get crackin’.
Using 1,000 images taken by 91 amateurs from around the world, Peter Rosen has created a high-resolution film of Jupiter's dynamic atmosphere. Credit: Peter Rosén et al. via YouTube
A renewed era of space exploration is underway. Compared to the Space Race of the 20th century, which was characterized by two superpowers locked in a game of “getting there first”, the new era is defined predominantly by cooperation and open participation. One way in which this is evident is the role played by “citizen scientists” and amateur astronomers in exploration missions.
Consider the recently-released short film titled “A Journey to Jupiter” by Peter Rosen – a photographer and digital artist in Stockholm, Sweden. Using over 1000 images taken by amateur planetary photographers from around the world, this film takes viewers on a virtual journey to the Jovian planet, showcasing its weather patterns and dynamic nature in a way that is truly inspiring.
The images that went into making this video were collected by over 91 amateur astronomers over the course of three and a half months (between December 19th, 2014 and March 31st, 2015). After Rosen collected them, he and his associates (Christoffer Svenske and Johan Warell) then spent a year remapping them into cylindrical projections. Rosen then added color corrections, and stitched all the images into a total of 107 maps.
Much like fast-motion videos that illustrate weather patterns on Earth, or the passage of the stars across the night sky, the end result of was a film that shows the motions of Jupiter’s cloud belts and its Great Red Spot in high-resolution. Some 250 revolutions of the planet are illustrated, including from the equatorial band, the south pole, and the north pole.
As Rosen told Universe Today via email, this project was the latest in a lifelong pursuit of making astronomy accessible to the public:
“I have been into Astronomy since I was a teenager in the early 1970’s and immediately I got a passion for astrophotography, and more specifically, photographing the planets. I see astronomy as a life-long passion, so it is quite normal to strive for an evolution in what you do. I had an idea growing slowly for some years that it should be possible to animate the cloud belts of Jupiter and reveal the intricate dynamics of its flows, not just taking still pictures that might point to the changes in the structures but without the obvious visual dynamics of an animation.”
“A Journey to Jupiter” was also Rosen’s contribution to the Mission Juno Pro-Amateur Collaboration Project, of which he is part. Established by Glenn Orton of NASA’s Jet Propulsion Laboratory, this effort is one of several that seeks to connect amateurs and professionals in support of space exploration. Back in May of 2016, this group met in Nice, France, for a workshop dedicated to projects and techniques related to Jupiter observations.
Still-pic from Rosen’s “A Journey to Jupiter” video. Credit: Peter Rosen et al via Youtube.
Among other items discussed was the limitations that missions like Juno have to deal with. While it is capable of taking very-high resolution images of Jupiter, these images are highly specific in nature. And before a team of mission scientists are able to color-correct them and stitch them together to create panoramas, etc., they are not always what you might call “visually stunning”.
However, Earth-based observatories are not hampered by this restriction, and can take multiple images of a planet over time that capture it as a whole. And thanks to the availability of sophisticated telescopes and imaging software, amateur astronomers are capable of making important contributions in this regard. And far from these being strictly for scientific purposes, there is also the added benefit of public engagement.
“This has been a very technical and scientifically correct project,” said Rosen, “but as a photographer and digital artist I also wanted to create a work of art that would inspire and appeal to people who are fascinated by the universe but who are not necessarily into astronomy.”
Of course, this does not detract from the scientific value that this film has. For example, it showcases the turbulent nature of Jupiter’s atmosphere in a way that is scientifically accurate. Hence why Ricardo Hueso Alonso – a physicist at the University of Basque Country and a member of the Planetary Virtual Observatory and Laboratory (PVOL) – plans to use the maps to measure Jupiter’s wind speeds at different latitudes.
Reprocessed image taken by the JunoCam during its 3rd close flyby of the planet on Dec. 11. The photo highlights two large ‘pearls’ or storms in Jupiter’s atmosphere. Credit: NASA/JPL-Caltech/SwRI/MSSS
On top of its artistic and scientific merit, “A Journey to Jupiter” also serves as a testament to the skill and capability of the today’s amateur astronomers and planetary photographers. And of course, it draws attention to the efforts of space missions such as Juno, which is currently skimming the clouds of Jupiter to obtain the most comprehensive information about the planet’s atmosphere and magnetic field to date.
Not surprisingly, this is not the first film by Rosen that combines scientific accuracy and fast-motion visuals. The short film Voyager3, released back in June of 2014, was an homage by Rosen and six other Swedish amateur astronomers to the Voyager 1 mission. As the probe made its 28-day final approach to Jupiter in 1979, it snapped what were the most detailed images of Jupiter at the time.
These images helped to improve our understanding of the gas giant, its atmosphere, and its moons. Among other things, hey revealed the turbulent nature of Jupiter’s atmosphere, and that the Great Red Spot had changed color since the Pioneer 10 and 11 missions had flown by in 1973 and 74. Produced 35 years later, Voyager 3 was an attempt to recreate this historic event using images taken by Swedish amateur astronomers using their own ground-based telescopes.
Over the course of 90 days, Rosen and his colleagues captured one million frames of Jupiter, which resulted in 560 still images of the planet. These were then stitched together using a series of software programs (Winjupos, Photoshop CS6, Fantamorph, and StarryNightPro+) to create a simulation that gives the impression of a probe approaching the planet – i.e. like a third Voyager mission, hence the name of the film.
“As Jupiter was ideally positioned high in the sky in 2013-2014 for us living far up in the northern hemisphere, I decided that it was the right moment to give it a try, so I contacted 6 other amateurs on our local forum that shared my passion for the planets,” Rosen said. “We photographed Jupiter as often as we could during a 3-month period and I took care of the processing of the images which took me a total of 6 months.”
It is an exciting time to be alive. Not only are a greater number of national space agencies taking part in the exploration of the Solar System; but more than ever, citizen scientists, amateurs and members of the general public are able to participate in a way that was never before possible.
To view more work by Peter Rosen, be sure to check out his page at Vimeo.
First SpaceX Falcon 9 rocket stands erect atop Launch Complex 39-A at the Kennedy Space Center on 10 Feb 2017 as seen from Playalinda Beach, Fl. This is the first rocket to stand on pad 39A since the retirement of NASA’s Space Shuttles in July 2011. Liftoff to the ISS is slated for 18 Feb 2017 on the CRS-10 resupply mission for NASA. Credit: Jeff Seibert/AmericaSpace
First SpaceX Falcon 9 rocket stands erect atop Launch Complex 39-A at the Kennedy Space Center on 10 Feb 2017 as seen from Playalinda Beach, Fl. This is the first rocket to stand on pad 39A since the retirement of NASA’s Space Shuttles in July 2011. Liftoff to the ISS is slated for 18 Feb 2017 on the CRS-10 resupply mission for NASA. Credit: Jeff Seibert/AmericaSpace
KENNEDY SPACE CENTER, FL – The first SpaceX Falcon 9 rocket ever to grace historic launch pad 39A at NASA’s Kennedy Space Center in Florida was erected this afternoon, Friday, Feb. 10, to prepare the booster for a critical static fire sometime Saturday, and a launch to the space station next weekend – if all goes well.
This marks the first time any rocket has stood on pad 39A since the retirement of NASA’s Space Shuttles in July 2011.
Liftoff of the Falcon 9 is slated for no earlier than next Saturday, 18 Feb 2017 on a critical cargo flight for NASA to deliver over two and a half tons of science and supplies to the six person crew living and working on the International Space Station (ISS).
The rocket – minus the payload comprising the Dragon cargo spacecraft – was rolled out of the SpaceX processing hangar at the perimeter fence and then up the incline to the top of pad 39A this morning using a dedicated transporter-erector.
A wider-angle shot from the top of the CBS bureau at KSC showing the first SpaceX Falcon 9 atop pad 39A 3.1 miles away on Feb 20, 2017. Credit: Bill Harwood/CBS News
The booster was then hoisted into launch position this afternoon.
The scene was viewed by spectators including my space journalist colleague Jeff Seibert.
First SpaceX Falcon 9 rocket stands erect atop Launch Complex 39-A at the Kennedy Space Center on 10 Feb 2017 as seen from Playalinda Beach, Fl. This is the first rocket to stand on pad 39A since the retirement of NASA’s Space Shuttles in July 2011. Liftoff to the ISS is slated for 18 Feb 2017 on the CRS-10 resupply mission for NASA. Credit: Jeff Seibert/AmericaSpace
The historic NASA launch pad was formerly used to launch both America’s space shuttles and astronauts on Apollo/Saturn V moon landing missions.
SpaceX CEO Elon Musk also posted a photo on instagram with this caption:
“Falcon 9 rocket now vertical at Cape Canaveral on launch complex 39-A. This is the same launch pad used by the Saturn V rocket that first took people to the moon in 1969. We are honored to be allowed to use it.”
First SpaceX Falcon 9 rocket stands erect atop Launch Complex 39-A at the Kennedy Space Center on 10 Feb 2017. The photo was posted to Instagram by SpaceX CEO Elon Musk. Credit: Elon Musk/SpaceX
After the successful completion of the static fire test, the booster will be rolled back to the big processing hangar and the Dragon resupply ship will be integrated on top.
During the brief static fire test, all 9 Merlin 1D first stage engines are ignited for a few seconds to confirm they and the rocket are suited for liftoff while hold down clamps restrain the rocket on the pad.
Dragon will be loaded with more than 5500 pounds of equipment, gear, food, supplies and NASA’s Stratospheric Aerosol Gas Experiment III (SAGE III) ozone mapping science payload.
Engineers at work processing NASA’s Stratospheric Aerosol and Gas Experiment III, or SAGE III instrument inside the Space Station Processing Facility at NASA’s Kennedy Space Center in Florida during exclusive visit by Ken Kremer/Universe Today in December 2016. Technicians are working in a super-clean ‘tent’ built in the SSPF high bay to protect SAGE III’s special optics and process the Ozone mapper for upcoming launch on the SpaceX CRS-10 Dragon cargo flight to the International Space Station in early 2017. Credit: Ken Kremer/kenkremer.com
Pad 39A has lain dormant for launches for nearly six years since Space Shuttle Atlantis launched on the final shuttle mission STS 135 in July 2011.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
SpaceX crews are renovating Launch Complex 39A at the Kennedy Space Center for launches of commercial and human rated Falcon 9 rockets as well as the Falcon Heavy, as seen here during Dec 2016 with construction of a dedicated new transporter/erector. New rocket processing hangar sits at left. Credit: Ken Kremer/kenkremer.com
Earth, seen from space, above the Pacific Ocean. Credit: NASA
Whoever coined the phrase “it’s a small world” obviously never tried to travel around it! In truth, the planet’s dimensions are quite impressive, and determining just how big it is took many thousands of years. From astronomers determining that Earth was in fact round (and not a flat disc, cube or ziggurat), to the first successful attempts at circumnavigation, our estimates have changed over time.
And in the era of modern astronomy, improvements in instrumentation, methodology, and the ability to see Earth from space have certainly helped. According to modern estimates, the surface area of the Earth is approximately 510 million square km (5.1 x 108 km2) or 196,900,000 square miles. Determining this was not only a matter of ascertaining Earth’s dimensions, but also its proper shape.
Shape of the Earth:
For starters, and contrary to what scientists have believed since classical antiquity, Earth is not a perfect sphere. Since the 17th and 18th centuries – thanks to improvements made in the field of astronomy and geodesy (a branch of mathematics dealing with the measurement of the Earth) – scientists have understood that the Earth is actually a flattened sphere.
This is what is known as an “oblate spheroid”, which is a sphere that is wider at its horizontal axis than it is at its vertical axis. According to the 2004 Working Group of the International Earth Rotation and Reference Systems Service (IERS), Earth experiences a flattening of 0.0033528 at the poles. This flattening is due to Earth’s rotational velocity – a rapid 1,674.4 km/h (1,040.4 mph) – which causes the planet to bulge at the equator.
Because of this, the diameter of the Earth at the equator is about 43 kilometers (27 mi) larger than the pole-to-pole diameter. The latest measurements indicate that the Earth has an equatorial diameter of 12,756 km (7926 mi), and a polar diameter of 12713.6 km (7899.86 mi). This is true for other planets in the Solar System that have rapid rotations (like Jupiter and Saturn), and even stars like the rapidly-spinning Altair.
Calculation:
Given its particular shape, calculating the Earth’s surface area requires a specific equation. Whereas determining the surface area of a sphere is a simple matter of multiplying pi by four, and these by the square of its radius (4 x 3.14159… x r²), to calculate the surface area of an oblate spheroid – where the distance from the center to a pole (c) is less than its semi-axis (a) – the following equation has to come into play:
Whereas S equals the surface area, c represents the distance from the center to a pole, and a represents the semi-axis, e represents the eccentricity. Naturally, Earth’s surface area can also be subdivided between water and land segments (aka. oceans or continental crust).
And since 70% of the Earth’s surface is covered by water, that works out to 361 million km² (139.4 million mi²). Earth’s continents, on the other hand, cover the remaining 149 million km² (57.5 or million mi²). This is a phenomena unique to Earth (at least in our Solar System) since no other Solar planet has liquid water covering a significant amount of its surface.
Other Solar Planets:
Compared to the other planets of the Solar System, Earth ranks somewhere in the middle. Of the terrestrial planets (i.e. Mercury, Venus, Earth and Mars) it is the largest. However, when compared to the gas giants (Jupiter, Saturn, Uranus and Neptune) it comes in dead last! Let’s see just how Earth stacks up against these other worlds…
Mercury is the smallest planet in our Solar System (ever since the 2006 IAU decision that designated Pluto as “dwarf planet”). It has a surface area of 7.48 x 107 km2, which is only about 15% of Earth’s surface area. Venus is similar in size to Earth, hence why it has earned the title of “Earth’s Sister Planet”. Consistently, Venus has a surface area of 4.6 x 108 km2, which is roughly 90% of Earth’s.
Mars is also a small planet, the second smallest in our Solar System. This is evident in Mars’ diminutive surface area of 1.45 x 108 km2, which is roughly 28% that of Earth’s. Moving to the outer Solar System, it is quickly made apparent that all of the gas giants have the four planets of the inner Solar System beat (at least in a size contest)!
An illustration showing the 8 planets of the Solar System to scale. Credit: NASA
Jupiter is the largest planet in our Solar System, with a surface area of 6.14 x 1010 km2 – which is about 122 times greater than the surface area of Earth! Saturn is the second largest planet in our Solar System and has a surface area of 4.27 x 1010 km2 – which is roughly 83.7 times that of Earth.
As for the “ice giants”, Uranus has a surface area of 8.1156 x 109 km2 (15.91 times that of Earth) while Neptune has a slightly smaller surface area of 7.618 x 109 km2, which is close to 15 times that of Earth.
All told, Earth is relatively spacious place, as terrestrial bodies go. But the amount of surface that we humans can actually live on is rather limited. Once you subtract all the space that’s occupied by water, you begin to see that the world may be a little on the smallish side after all.
The Centaurus A galaxy (NGC 5128), a luminous galaxy located in the Centaurus constellation. Credit: ESO
Welcome back to Constellation Friday! Today, in honor of the late and great Tammy Plotner, we will be dealing with the “Centaur”, the Centaurus constellation!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age.
One of these is the famous Centaur of classical antiquity, otherwise known as the constellation Centaurus. As one of the 48 constellation included in the Almagest, it is now one of the 88 modern constellations recognized by the IAU. Located in the southern sky, this constellation is bordered by the Antlia, Carina, Circinus,Crux,Hydra,Libra,Lupus,Musca, and Vela constellations.
Name and Meaning:
In classic Greco-Roman mythology, Centaurus is often associated with Chiron the Centaur – the wise half-man, half-horse who was a teacher to both Hercules and Jason and the son of the Titan king Cronus and the sea nymph Philyra. According to legend, Cronus seduced the nymph, but they were interrupted by Cronus’ wife Rhea. To evade being caught in the act, Cronus turned himself into a horse.
Centaurus, as depicted on a globe created by Gullielmus Janssonius Blaeu (1602), photographed at Skokloster Castle in Stockholm, Sweden. Credit: Wikipedia Commons/Erik Lernestål
As a result, Philyra gave birth to a hybrid son. He died a tragic death in the end, having been accidentally struck by one of Heracles’ poisoned arrows. As an immortal god, he suffered terrible pains but could not die. Zeus eventually took pity on the centaur and released him from immortality and suffering, allowing him to die, and placed him among the stars.
It is believed that the constellation of Sagitta is the arrow which Chiron fired towards Aquila the Eagle to release the tortured Prometheus. The nearby constellation of Lupus the Wolf may also signify an offering of Hercules to Chiron – whom he accidentally poisoned. Just as Virgo above represents the maid placed in the sky as a sign of pity for the Centaur’s plight.
History of Observation:
The first recorded examples of Centaurus date back to ancient Sumeria, where the constellation was depicted as the Bison-man (MUL.GUD.ALIM). This being was depicted in one of two ways – either as a four-legged bison with a human head, or as a creature with a human head and torso attached to the rear legs of a bison or bull. In the Babylonian pantheon, he was closely associated with the Sun god Utu-Shamash.
The Greek depiction of the constellation as a centaur is where its current name comes from. Centaurus is usually depicted as sacrificing an animal, represented by the constellation Lupus, to the gods on the altar represented by the Ara constellation. The centaur’s front legs are marked by two of the brightest stars in the sky, Alpha and Beta Centauri (aka. Rigil Kentaurus and Hadar), which also serve as pointers to the Southern Cross.
Johannes Hevelius’ depiction of Centaurus, taken from Uranographia (1690). Credit: NASA/Chandra
In the 2nd century AD, Ptolemy catalogued 37 stars in the constellation and included it as one of the 48 constellations listed in the Almagest. In 1922, it was included in the 88 modern constellations recognized by the International Astronomical Union (IAU).
Notable Features:
Centaurus contains 11 main stars, 9 bright stars and 69 stars with Bayer/Flamsteed designations. Its brightest star – Alpha Centauri (Rigel Kentaurus) – is the Solar System’s closest neighbor. Located just 4.365 light years from Earth, this multiple star system consists of a yellow-white main sequence star that belongs to the spectral type G2V (Alpha Centauri A), and a spectral type K1V star (Alpha Centauri B).
Alpha Centauri A, the brightest component in the system, is the fourth brightest individual star (behind Arcturus) in the night sky, B is the 21st individual brightest star in the sky. Taken together, however, they are brighter than Arcturus, and rank third among the brightest star system (behind Sirius and Canopus). The two stars are believed to be roughly the same age – ~4.85 billion years old – and are close in mass to our Sun.
Proxima Centauri, a red dwarf system (spectral class M5Ve or M5Vie), if often considered to be a third member of this star system. Located about 0.24 light years from the binary pair (and 4.2 light years from Earth), this star system was confirmed in 2016 to be home to the closest exoplanet to Earth (Proxima b).
The two brightest stars of the Centaurus constellation – (left) Alpha Centauri and (right) Beta Centauri. The faint red star in the center of the red circle is Proxima Centauri. Credit: Wikipedia Commons/Skatebiker
Then there’s Beta Centauri, a blue-white giant star (spectral class B1III) located 348.83 light years from Earth that is the tenth brightest star in the sky. The star’s traditional names (Hadar or Agena), are derived from the Arabic words for “ground” and “the knee”, respectively. This multiple star system consists of Hadar A, a spectroscopic binary of two identical stars, while Hadar B orbits the primary pair with a period of at least 250 days.
Next up is Theta Centauri (aka. Menkent), an orange K-type giant (spectral class K0IIIb) that is located approximately 60.9 light years from Earth. Its traditional name, which comes from its location in the constellation, translates to “shoulder of the Centaur” in Arabic.
And then there’s Gamma Centauri (Muhlifain), a binary star system located 130 light years from Earth which is composed of two stars belonging to the spectral type A0. It’s name is translated from Arabic and means “two things”, or the “swearing of an oath”, which appears to be a case of name-transfer from Muliphein, a star located in the Canis Majoris constellation.
The constellation is also home to many Deep Sky Objects. For instance, there is the Centaurus A galaxy, the fifth brightest galaxy in the sky and one of the closest radio galaxies to the Solar System (between 10 and 16 million light years distant). The galaxy has an apparent visual magnitude of 6.84 and is believed to contain a supermassive black hole at its center.
Image of the Centaurus A galaxy, combining optical, x-ray and infrared data. Credit: X-ray: NASA/CXC/SAO/Rolf Olsen/JPL-Caltech
Centaurus A’s brightness is attributed to the intense burst of star formation going on inside it, which is believed to be the result of it undergoing a collision with a spiral galaxy. Centaurus A is located at the center of the Centaurus A subgroup of the Centaurus A/M83 Group of galaxies, which includes the Southern Pinwheel Galaxy (aka. Messier 83, M83).
Then there’s the famous Omega Centauri globular cluster, one of the brightest globular clusters in the Milky Way. Located approximately 15,800 light years distant, this cluster is bright enough to be visible to the naked eye. Originally listed as a star by Ptolemy in the Almagest, the cluster’s true nature was not discovered until John Herschel studied it in the early 19th century.
Next up is NGC 4945, one of the brightest galaxies in the Centaurus A/M83 group, and the second brightest galaxy in the Centaurus A subgroup. The spiral galaxy is approximately 11.7 million light years distant and has an active Seyfert II nucleus, which could be due to the presence of a supermassive black hole at its center.
The galaxy NGC 4650A is also located in Centaurus, some 130 million light years from Earth. This galaxy is one of only 100 polar-ring galaxies known to exist, which are so-named because their outer ring of stars and gas rotate over the poles of the galaxy. These rings are believed to have formed from the gravitational interaction of two galaxies, or from a collision with a smaller galaxy in the past.
The Blue Planetary (NGC 3918), as imaged by the Hubble telescope. Credit: ESA/Hubbl/e NASA
The Blue Planetary nebula (aka. the Southerner), is a bright planetary nebula in Centauru, approximately 4,900 light years distant. With an apparent visual magnitude of 8.5, it is the brightest planetary nebula in the far southern region of the sky and and can be observed in a small telescope.
Finding Centaurus:
Centaurus is one of the largest constellations in the night sky – covering over 1000 square degrees – and the brightest in the southern hemisphere. For observers located at latitudes between +30° and -90°, the entire constellation is visible and the northern portion of the constellation can be spotted easily from the northern hemisphere during the month of May.
For the unaided southern skies observer, the constellation of Centaurus holds a gem within its grasp – Omega Centauri (NGC 5139). But of course, this object isn’t a star – despite being listed on the catalogs as its Omega star. It’s a globular cluster, and the biggest and brightest of its kind known to the Milky Way Galaxy. Though visible to the naked eye, it is best observed through a telescope or with binoculars.
This 18,300 light-year beauty contains literally millions of stars with a density so great at its center the stars are less than 0.1 light year apart. It is possible Omega Centauri may be the remains of a galaxy cannibalized by our own. Even to this present day, something continues to pull at NGC 5139’s stars… tidal force? Or an unseen black hole?
Omega Centauri (NGC 5139), a massive globular cluster that is part of the Centaurus constellation. Credit: Jose Mtanous
Now, hop down to Alpha. Known as Rigil Kentaurus, Rigil Kent, or Toliman, is the third brightest star in the entire night sky and the closest star system to our own solar system. To the unaided eye it appears a single star, but it’s actually a binary star system. Alpha Centauri A and Alpha Centauri B are the individual stars and a distant, fainter companion is called Proxima Centauri – a red dwarf that is the nearest known star to the Sun.
Oddly enough, Proxima Centauri is also a visual double, which is assumed to be associated with Centaurus AB pair. Resolution of the binary star Alpha Cen AB is too close to be seen by the naked eye, as the angular separation varies between 2 and 22 arc seconds, but during most of the orbital period, both are easily resolved in binoculars or small telescopes.
Then stop for a moment to take a look at Beta Centauri. Beta Centauri is well-known in the Southern Hemisphere as the inner of the two “Pointers” to the Southern Cross. A line made from the other pointer, Alpha Centauri, through Beta Centauri leads to within a few degrees of Gacrux, the star at the top of the cross. Using Gacrux, a navigator can draw a line with Acrux to effectively determine south.
But, that’s not all! Hadar is also a very nice double star, too. The blue-white giant star primary is also a spectroscopic binary, accompanied by a widely spaced companion separated from the primary by 1.3″. Or try Gamma Centauri! Muhlifain has an optical companion nearby, but check it out in the telescope… it’s really two spectral type A0 stars each of apparent magnitude +2.9!
The location of the Centaurus constellation in the southern sky. Credit: IAU/Sky & Telescope magazine/Roger Sinnott & Rick Fienberg
For binoculars or telescopes, hop on over to Centaurus A. This incredible radio source galaxy is one of the closest to Earth and also the fifth brightest in the sky. When seen through an average telescope, this galaxy looks like a lenticular or elliptical galaxy with a superimposed dust lane, and oddity first noted in 1847 by John Herschel.
The galaxy’s strange morphology is generally recognized as the result of a merger between two smaller galaxies and photographs reveal a jet of material streaming from the galactic core. Although we cannot see it, there may be a supermassive black hole at the center of the galaxy is responsible for emissions in the X-ray and radio wavelengths!
For binoculars and rich field telescopes, head towards the Crux border and center on Lambda Centauri for open cluster, IC2944. Also known on some observing lists as Caldwell 100, this scattered star cluster contains about 30 stellar members and some faint nebulosity. About 2 degrees southwest of Beta you’ll find another pair of open clusters, NGCs 5281 and 5316. Or try your hand just about a degree west of Alpha for open cluster, NGC5617. These last three are far more rich in stars and photon satisfying!
Centaurus has been known to human astronomers since the Bronze Age and has gone through some changes since that time. But even after thousands of years’ time, the Centaur is still hunting in the night sky! And for those who love viewing classic constellations and bright objects, it still provides viewing opportunities that are bound to dazzle the eyes and inspire the mind!
