There are services which will let you name a star in the sky after a loved one. You can commemorate a special day, or the life of an amazing person. But can you really name a star?
The answer is yes, and no.
Names of astronomical objects are agreed upon by the International Astronomical Union. If this name sounds familiar, it’s the same people who voted that Pluto is not a planet.
Them.
There are a few stars with traditional names which have been passed down through history. Names like Betelgeuse, Sirius, or Rigel. Others were named in the last few hundred years for highly influential astronomers.
These are the common names, agreed upon by the astronomical community.
Most stars, especially dim ones, are only given coordinates and a designation in a catalog. There are millions and millions of stars out there with a long string of numbers and letters for a name. There’s the Gliese catalog of nearby stars, or the Guide Star Catalog which contains 945 million stars.
The IAU hasn’t taken on any new names for stars, and probably won’t ever. The bottom line is that numbers are much more useful for astronomers searching and studying stars.
But what about the companies that will offer to let you name a star? Each of these companies maintains their own private database containing stars from the catalog and associated star names. They’ll provide you with a nice certificate and instructions for finding it in the sky, but these names are not recognized by the international astronomical community.
You won’t see your name appearing in a scientific research journal. In fact, it’s possible that the star you’ve named with one organization will be given a different name by another group.
So can you really name a star after yourself or a loved one?
The Fraser Cain Tower of Awesomeness.Yes, you can, in the same way that you can name an already-named skyscraper after yourself. Everyone else might keep calling it the Empire State Building, but you’ll have a certificate that says otherwise.
There are a few objects that can be named, and recognized by the IAU.
Fragments of Shoemaker-Levy 9 on approach to Jupiter (NASA/HST)If you’re the first person to spot a comet, you’ll have it named after you, or your organization. For example, Comet Shoemaker-Levy was discovered simultaneously by Eugene Shoemaker and David Levy.
If you discover asteroids and Kuiper Belt Objects, you can suggest names which may be ratified by the IAU. Asteroids, as well as comets, get their official numerical designation, and then a common name.
The amateur astronomer Jeff Medkeff, who tragically died of liver cancer at age 40, named asteroids after a handful of people in the astronomy, space and skeptic community.
Artist’s impression of ErisKuiper Belt Objects are traditionally given names from mythology. And so, Pluto Killer Mike Brown’s Caltech team suggested the names for Eris, Haumea and Makemake.
So what about extrasolar planets? Right now, these planets are attached to the name of the star. For example, if a planet is discovered around one of the closer stars in the Gliese catalog, it’s given a letter designation.
An organization called Uwingu is hoping to raise funds to help discover new extrasolar planets, and then reward those funders with naming rights, but so far, this policy hasn’t been adopted by the IAU.
Personally, I think that officially allowing the public to name astronomical objects would be a good idea. It would spur the imagination of the public, connecting them directly to the amazing discoveries happening in space, and it would help drive funds to underfunded research projects.
The new nova is located in Delphinus alongside the familiar Summer Triangle outlined by Deneb, Vega and Altair. This may shows the sky looking high in the south for mid-northern latitudes around 10 p.m. local time in mid-August. The new object is ideally placed for viewing. Stellarium
Looking around for something new to see in your binoculars or telescope tonight? How about an object whose name literally means “new”. Japanese amateur astronomer Koichi Itagaki of Yamagata discovered an apparent nova or “new star” in the constellation Delphinus the Dolphin just today, August 14. He used a small 7-inch (.18-m) reflecting telescope and CCD camera to nab it. Let’s hope its mouthful of a temporary designation, PNVJ20233073+2046041, is soon changed to Nova Delphini 2013!
This map shows Delphinus and Sagitta, both of which are near the bright star Altair at the bottom of the Summer Triangle. You can star hop from the top of Delphinus to the star 29 Vulpeculae and from there to the nova. Or you can point your binoculars midway between Eta Sagittae and 29 Vul. The “5.7 star” is magnitude 5.7. Stellarium
Several hours later it was confirmed as a new object shining at magnitude 6.8 just under the naked eye limit. This is bright especially considering that nothing was visible at the location down to a dim 13th magnitude only a day before discovery. How bright it will get is hard to know yet, but variable star observer Patrick Schmeer of Germany got his eyes on it this evening and estimated the new object at magnitude 6.0. That not only puts it within easy reach of all binoculars but right at the naked eye limit for observers under dark skies. Wow! Since it appears to have been discovered on day one of the outburst, my hunch is that it will brighten even further.
Here’s a reverse “black stars on white” map some observers prefer for greater clarity. Stars are shown to 9th magnitude. Tycho visual magnitudes shown for 4 stars near the nova. The nova’s precise position is RA 20 h 23′ 31″, Dec. +20 deg. 46′. Created with Chris Marriott’s SkyMap
The only way to know is to go out for a look. I’ve prepared a couple charts you can use to help you find and follow our new guest. The charts show stars down to about 9th magnitude, the limit for 50mm binoculars under dark skies. The numbers on the chart are magnitudes (with decimals omitted, thus 80 = 8.0 magnitude) so you can approximate its brightness and follow the ups and downs of the star’s behavior in the coming nights.
Despite the name, a nova is not truly new but an explosion on a star otherwise too faint for anyone to have noticed. A nova occurs in a close binary star system, where a small but extremely dense and massive (for its size) white dwarf grabs hydrogen gas from its closely orbiting companion. After swirling about in a disk around the dwarf, it’s funneled down to the star’s 150,000 degree F surface where gravity compacts and heats the gas until it detonates like a bazillion thermonuclear bombs. Suddenly, a faint star that wasn’t on anyone’s radar vaults a dozen magnitudes to become a standout “new star”.
Model of a nova in the making. A white dwarf star pulls matter from its bloated red giant companion into a whirling disk. Material funnels to the surface where it later explodes. Credit: NASA/CXC/M. Weiss
Novae can rise in brightness from 7 to 16 magnitudes, the equivalent of 50,000 to 100,000 times brighter than the sun, in just a few days. Meanwhile the gas they expel in the blast travels away from the binary at up to 2,000 miles per second. This one big boom! Unlike a supernova explosion, the star survives, perhaps to “go nova” again someday.
Closer view yet of the apparent nova showing a circle with a field of view of about 2 degrees. Stellarium
I’ll update with links to other charts in the coming day or two, so check back.
In February 2013, asteroid DA 2014 safely passed by the Earth. There are several proposals abounding about bringing asteroids closer to our planet to better examine their structure. Credit: NASA/JPL-Caltech
One scientific team has identified 12 “Easily Retrievable Objects” in our solar system that are circling the sun and would not cost too much to retrieve (in relative terms, of course!)
The definition of an ERO is an object that can be captured and brought back to a stable gravitational point near Earth (called a Lagrange point, or more specifically the L1/L2 points between the sun and the Earth.) The change in speed necessary in these objects to make them easily retrievable is “arbitrarily” set at 500 meters per second (1,641 feet/second) or less, the researchers stated.
Image of asteroid Vesta calculated from a shape model, showing a tilted view of the topography of the south polar region. This perspective shows the topography, but removes the overall curvature of Vesta, as if the giant asteroid were flat and not rounded. Credit: NASA
Catching the objects wouldn’t just be a technology demonstration, but also could shed some light into how the solar system formed. Asteroids are generally considered leftovers of the early days of the neighborhood; under our current understanding of the solar system’s history, a spinning disc of gas and dust gradually clumped into rocks and other small objects, which eventually crashed into each other and formed planets.
Also, steering these objects around has another benefit: teaching humans how to deflect potentially hazardous asteroids from smacking into the Earth and causing damage. As we were reminded about earlier this year, even smaller rocks such as the one that broke up over a portion of Russia can be hazardous.
Concept of NASA spacecraft with Asteroid capture mechanism deployed to redirect a small space rock to a stable lunar orbit for later study by astronauts aboard Orion crew capsule. Credit: NASA.
There are at least a couple of big limitations to the plan. The first is to make sure not to put the asteroid in a path that would hit the Earth. The second is that he L1 and L2 points are somewhat unstable, so over time the asteroid would drift from its spot. It would need a nudge every so often to keep it in that location.
For the curious, this is the complete list of possible asteroids: 2006 RH120, 2010 VQ98, 2007 UN12, 2010 UE51, 2008 EA9, 2011 UD21, 2009 BD, 2008 UA 202, 2011 BL45, 2011 MD, 2000 SG344 and 1991 VG.
A binary black hole pair with an accretion disk inclined 45 degrees. Source: Nixon et al.
Since their discovery, supermassive black holes – the giants lurking in the center of every galaxy – have been mysterious in origin. Astronomers remain baffled as to how these supermassive black holes became so massive.
New research explains how a supermassive black hole might begin as a normal black hole, tens to hundreds of solar masses, and slowly accrete more matter, becoming more massive over time. The trick is in looking at a binary black hole system. When two galaxies collide the two supermassive black holes sink to the center of the merged galaxy and form a binary pair. The accretion disk surrounding the two black holes becomes misaligned with respect to the orbit of the binary pair. It tears and falls onto the black hole pair, allowing it to become more massive.
In a merging galaxy the gas flows are turbulent and chaotic. Because of this “any gas feeding the supermassive black hole binary is likely to have angular momentum that is uncorrelated with the binary orbit,” Dr. Chris Nixon, lead author on the paper, told Universe Today. “This makes any disc form at a random angle to the binary orbit.
Nixon et al. examined the evolution of a misaligned disk around a binary black hole system using computer simulations. For simplicity they analyzed a circular binary system of equal mass, acting under the effects of Newtonian gravity. The only variable in their models was the inclination of the disk, which they varied from 0 degrees (perfectly aligned) to 120 degrees.
After running multiple calculations, the results show that all misaligned disks tear. Watch tearing in action below:
In most cases this leads to direct accretion onto the binary.
“The gravitational torques from the binary are capable of overpowering the internal communication in the gas disc (by pressure and viscosity),” explains Nixon. “This allows gas rings to be torn off, which can then be accreted much faster.”
Such tearing can produce accretion rates that are 10,000 times faster than if the exact same disk were aligned.
In all cases the gas will dynamically interact with the binary. If it is not accreted directly onto the black hole, it will be kicked out to large radii. This will cause observable signatures in the form of shocks or star formation. Future observing campaigns will look for these signatures.
In the meantime, Nixon et al. plan to continue their simulations by studying the effects of different mass ratios and eccentricities. By slowly making their models more complicated, the team will be able to better mimic reality.
Quick interjection: I love the simplicity of this analysis. These results provide an understandable mechanism as to how some supermassive black holes may have formed.
While these results are interesting alone – based on that sheer curiosity that drives the discipline of astronomy forward – they may also play a more prominent role in our local universe.
Before we know it (please read with a hint of sarcasm as this event will happen in 4 billion years) we will collide with the Andromeda galaxy. This rather boring event will lead to zero stellar collisions and a single black hole collision – as the two supermassive black holes will form a binary pair and then eventually merge.
Without waiting for this spectacular event to occur, we can estimate and model the black hole collision. In 4 billion years the video above may be a pretty good representation of our collision with the Andromeda galaxy.
The results have been published in the Astrophysical Journal Letters (preprint available here). (Link was corrected to correct paper on 8/15/2013).
A solar cycle montage from August 1991 to September 2001 in X-rays courtesy of the Yohkoh Solar Observatory. (Credit: David Chenette, Joseph B. Gurman, Loren W. Acton, image in the public Domain).
The Sun has provided no shortage of mysteries thus far during solar cycle #24.
And perhaps the biggest news story that the Sun has generated recently is what it isn’t doing. As Universe Today recently reported, this cycle has been an especially weak one in terms of performance. The magnetic polarity flip signifying the peak of the solar maximum is just now upon us, as the current solar cycle #24 got off to a late start after a profound minimum in 2009…
Or is it?
Exciting new research out of the University of Michigan in Ann Arbor’s Department of Atmospheric, Oceanic and Space Sciences published in The Astrophysical Journal this past week suggests that we’re only looking at a portion of the puzzle when it comes to solar cycle activity.
Traditional models rely on the monthly averaged sunspot number. This number correlates a statistical estimation of the number of sunspots seen on the Earthward facing side of the Sun and has been in use since first proposed by Rudolf Wolf in 1848. That’s why you also hear the relative sunspot number sometimes referred to as the Wolf or Zürich Number.
But sunspot numbers may only tell one side of the story. In their recent paper titled Two Novel Parameters to Evaluate the Global Complexity of the Sun’s Magnetic Field and Track the Solar Cycle, researchers Liang Zhao, Enrico Landi and Sarah E. Gibson describe a fresh approach to model solar activity via looking at the 3-D dynamics heliospheric current sheet.
The spiraling curve of the heliospheric current sheet through the inner solar system. (Graphic credit: NASA).
The heliospheric current sheet (or HCS) is the boundary of the Sun’s magnetic field separating the northern and southern polarity regions which extends out into the solar system. During the solar minimum, the sheet is almost flat and skirt-like. But during solar maximum, it’s tilted, wavy and complex.
Two variables, known as SD & SL were used by researchers in the study to produce a measurement that can characterize the 3-D complexity of the HCS. “SD is the standard deviation of the latitudes of the HCS’s position on each of the Carrington maps of the solar surface, which basically tells us how far away the HCS is distributed from the equator. And SL is the integral of the slope of HCS on that map, which can tell us how wavy the HCS is on each of the map,” Liang Zhao told Universe Today.
Ground and space-based observations of the Sun’s magnetic field exploit a phenomenon known as the Zeeman Effect, which was first demonstrated during solar observations conducted by George Ellery Hale using his new fangled invention of the spectrohelioscope in 1908. For the recent study, researchers used data covering a period from 1975 through 2013 to characterize the HCS data available online from the Wilcox Solar Observatory.
SD and SL parameters juxtaposed against the traditional monthly sunspot number (SSN). Note the smooth fit until the end of solar cycle #23 around 2003. (Credit: Liang Zhao/The Astrophysical Journal).
Comparing the HCS value against previous sunspot cycles yields some intriguing results. In particular, comparing the SD and SL values with the monthly sunspot number provide a “good fit” for the previous three solar cycles— right up until cycle #24.
“Looking at the HCS, we can see that the Sun began to act strange as early as 2003,” Zhao said. “This current cycle as characterized by the monthly sunspot number started a year late, but in terms of HCS values, the maximum of cycle #24 occurred right on time, with a first peak in late 2011.”
“Scientists believe there will be two peaks in the sunspot number in this solar maximum as in the previous maximum (in ~2000 and ~2002),” Zhao continued, “since the Sun’s magnetic fields in the north and south hemispheres look asymmetric, and the north evolved faster than the south recently. But so far as I can see, the highest value of monthly-averaged sunspot number in this cycle 24 is still the one in the November 2011. So we can say the first peak of cycle 24 could be in November of 2011, since it is the highest monthly sunspot number so far in this cycle. If there is a second peak, we will see it sooner or later.”
The paper also notes that although cycle 24 is especially weak when compared to recent cycles, its range of activity is not unique when compared with solar cycles over the past 260 years.
HCS curves plotted on the surface of the Sun. Comparisons are made for the solar maximum on October 2000 (CR 1968), descending phase on April 2005 (2029), solar minimum on September 2009 (CR 2087), and ascending phase on March 2010 (CR2094). CR=Carrington Rotation. (Credit: Liang Zhao, The Astrophysical Journal).
The HCS value characterizes the Sun over one complete Carrington Rotation of 27 days. This is an averaged value for the rotation of the Sun, as the poles rotate slower than the equatorial regions.
The approximately 22 year span of time that it takes for the poles to reverse back to the same polarity again is equal to two average 11 year sunspot cycles. The Sun’s magnetic field has been exceptionally asymmetric during this cycle, and as of this writing, the Sun has already finished its reversal of the north pole first.
This sort of asymmetry during an imminent pole reversal was first recorded during solar cycle 19, which spanned 1954-1964. Solar cycles are numbered starting from observations which began in 1749, just four decades after the end of the 70-year Maunder Minimum.
“This is an exciting time to study the magnetic field of the Sun, as we may be witnessing a return to a less-active type of cycle, more like those of 100 years ago,” NCAR/HAO senior scientist and co-author Sarah Gibson said.
A massive sunspot group that rotated into view in early July, 2013, one of the largest seen for solar cycle #24 thus far. (Credit: NASA/SDO).
But this time, an armada of space and ground-based observatories will scrutinize our host star like never before. The SOlar Heliospheric Observatory (SOHO) has already followed the Sun through the equivalent of one complete solar cycle— and it has now been joined in space by STEREO A & B, JAXA’s Hinode, ESA’s Proba-2 and NASA’s Solar Dynamics Observatory. NASA’s Interface Region Imaging Spectrograph (IRIS) was also launched earlier this year and has just recently opened for business.
Will there be a second peak following the magnetic polarity reversal of the Sun’s south pole, or is Cycle #24 about to “leave the building?” And will Cycle #25 be absent all together, as some researchers suggest? What role does the solar cycle play in the complex climate change puzzle? These next few years will prove to be exciting ones for solar science, as the predictive significance of HCS SD & SL values are put to the test… and that’s what good science is all about!
-Read the abstract with a link to the full paper in The Astrophysical Journal by University of Michigan researchers here.
A Xombie technology demonstrator from Masten Space Systems. Credit: NASA/Masten
It’s frustrating to make it all the way to Mars, only to land in the wrong spot. So as Masten Space Systems tests its Xombie vertical-launch-vertical-landing rocket prototype on Earth, engineers are also examining a software solution to make Red Planet landings even more precise.
The software is called G-FOLD (for Fuel Optimal Large Divert Guidance algorithm) and is a product of NASA’s Jet Propulsion Laboratory and other NASA departments. The agency is using techniques for spacecraft landings that have origins from the Apollo moon missions of the 1960s, which have some limitations.
“These algorithms do not optimize fuel usage and significantly limit how far the landing craft can be diverted during descent,” JPL stated, adding that the new algorithm can figure out the best fuel-conserving paths in real time, along with a “key new technology required for planetary pinpoint landing.”
An artist’s concept of Curiosity landing with the skycrane system — demonstrating one recently used technique for landing on Mars. Credit: NASA/JPL
Hitting the target exactly is an exciting feat for researchers, JPL explained, because robotic missions can be steered to difficult-to-reach science targets and crewed missions could bring more cargo to their landing site rather than carrying extra fuel.
Xombie first tested out this technique on July 30 and nailed the landing — about half a mile away — when it received the commands while 90 feet in the air. A second flight is planned for August, providing the data analysis goes as planned.
The technology is still new, of course, and there are other concepts out there for pinpoint systems. In May, the European Space Agency released information on a concept it is funding. That system, which is also still being developed, uses a database of landmarks to assist a spacecraft with making landings.
Rocket science university students from Puerto Rico pose for photo op with the Terrier-Improved Malemute sounding rocket that will launch their own developed RockSat-X science experiments to space on Aug. 13 at 6 a.m. from NASA Wallops Flight Facility, VA. Credit: Ken Kremer/kenkremer.com
Rocket science university students from Puerto Rico pose for photo op with the Terrier-Improved Malemute sounding rocket that will launch their own developed RockSat-X science experiments to space on Aug. 13 at 6 a.m. from NASA Wallops Flight Facility, VA.
Credit: Ken Kremer/kenkremer.com[/caption]
WALLOPS ISLAND, VA – How many of you have dreamed of flying yourselves or your breakthrough experiments to the High Frontier? Well if you are a talented student, NASA may have a ticket for you.
A diverse group of highly motivated aerospace students from seven universities spread across the United States have descended on NASA’s Wallops Flight Facility along the Eastern Shore of Virginia to fulfill the dream of their lifetimes – launching their very own science experiments aboard a rocket bound for space.
I met the thrilled students and professors today beside their rocket at the Wallops Island launch pad.
On Aug 13, after years of hard work, an impressive array of research experiments developed by more than 40 university students will soar to space on the RockSat-X payload atop a 44-foot tall Terrier-Improved Malemute suborbital sounding rocket at 6 a.m. EDT.
Students from Northwest Nazarene University observe the pre-integration of their experiment into the RockSat-X payload at the NASA Wallops Flight Facility in June. Students from seven universities are participating in the program and will attend the launch on August 13. Credit: NASA/K. Koehler
The two stage rocket will rapidly ascend on a southeasterly trajectory to an altitude of some 97 miles and transmit valuable data in-flight during the 12-minute mission.
The launch will be visible to spectators in parts of Virginia, Maryland and Delaware, and perhaps a bit beyond. Check out the visibility map below.
The RockSat-X flight profile and visibility map. RockSat-X is scheduled to launch from NASA’s Wallops Flight Facility, VA on Aug. 13 at 6.a.m. EDT Credit: NASA
If you’re available, try venturing out to watch it. The available window lasts until 10 a.m. EDT if needed.
The students will put their classroom learning to the test with experiments and instruments built by their own hands and installed on the 20 foot long RockSat-X payload. The integrated payload accounts for nearly half the length of the Terrier Malamute suborbital rocket. It’s an out of this world application of the scientific method.
Terrier-Improved Malemute sounding rocket erected for launch of student experiments on RockSat-X payload on Aug. 13 at 6 a.m. from NASA Wallops Flight Facility, VA. Credit: Ken Kremer/kenkremer.comIncluded among the dozens of custom built student experiments are HD cameras, investigations into crystal growth and ferro fluids in microgravity, measuring the electron density in the E region (90-120km), aerogel dust collection on an exposed telescoping arm from the rockets side, effects of radiation damage on various electrical components, determining the durability of flexible electronics in the cryogenic environment of space and creating a despun video of the flight.
At the conclusion of the flight, the payload will descend to Earth via a parachute and splash down in the Atlantic Ocean approximately 86 miles offshore from Wallops.
Commercial fishing ships under contract to NASA will then recover the RockSat-X payload and return it to the students a few hours later, NASA spokesman Keith Koehler told Universe Today.
They will tear apart the payload, disengage their experiments and begin analyzing the data to see how well their instruments performed compared to the preflight hypotheses’.
RockSat-X is a joint educational activity between NASA and the Colorado Space Grant Consortium. It is the third of three practical STEM educational programs where the students must master increasingly difficult skill level requirements leading to a series of sounding rocket liftoffs.
In mid-June, some 50 new students participated in the successful ‘RockOn’ introductory level payload launch from Wallops using a smaller Terrier-Improved Orion rocket.
“The goal of the RockSat-X program is to provide students a hands-on experience in developing experiments for space flight,” said Chris Koehler, Director of the Colorado Space Grant Consortium.
“This experience allows these students to apply what they have learned in the classroom to a real world hands-on project.”
The students participating in this year’s RockSat-X launch program hail from the University of Colorado at Boulder; the University of Puerto Rico at San Juan; the University of Maryland, College Park; Johns Hopkins University, Baltimore, Md.; West Virginia University, Morgantown; University of Minnesota, Twin Cities; and Northwest Nazarene University, Nampa, Idaho.
Panoramic view of the NASA Wallops Flight Facility launch range at Virginia’s Eastern Shore during prior launch of two suborbital sounding rockets as part of the Daytime Dynamo mission. RockSat-X payload will launch on a Terrier-Improved Malemute sounding rocket. Credit: Ken Kremer/kenkremer.com
Some of these students today could well become the pioneering aerospace industry leaders of tomorrow!
In the event of a delay forced by weather or technical glitches, August 14 is the backup launch day.
A great place to witness the blastoff is from the NASA Wallops Visitor Center, offering a clear view to the NASA launch range.
It opens at 5 a.m. on launch day and is a wonderful place to learn about NASA missions – especially the pair of exciting and unprecedented upcoming launches of the LADEE lunar science probe to the moon and the Cygnus cargo carrier to the ISS in September.
Both LADEE and Cygnus are historic first of their kind flights from NASA Wallops.
Live coverage of the launch is available via UStream beginning at 5 a.m. on launch day at:
http://www.ustream.tv/channel/nasa-tv-wallops
…………….
Learn more about Suborbital Science, Cygnus, Antares, LADEE, MAVEN and Mars rovers and more at Ken’s upcoming presentations
Aug 12/13: “RockSat-X Suborbital Launch, LADEE Lunar & Antares Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM
Sep 5/6/16/17: LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM
Oct 3: “Curiosity, MAVEN and the Search for Life on Mars – (3-D)”, STAR Astronomy Club, Brookdale Community College & Monmouth Museum, Lincroft, NJ, 8 PM
More than 40 University students participating in the Aug. 13 RockSat-X science payload pose for photo op with the Terrier-Improved Malemute sounding rocket that will launch their own experiments to space from NASA Wallops Flight Facility, VA. Credit: Ken Kremer/kenkremer.com
We have another great app giveaway for you, our valued readers. Star Walk is an app that allows you to point your iPhone at the night sky to provide names and descriptions of all the objects you are seeing. Furthermore, you can click on any individual star, satellite, planet or constellation and an in depth description will conveniently pop up on your screen. Whether you live in the city with lots of light pollution or in the country where there are more stars than black, this app will fill you in on all of the celestial objects you can (or can’t) see.
From the developer:
Star Walk is an award-winning Education app that allows users to easily locate and identify 20,000+ objects in the night sky. The 360-degree, touch control star map displays constellations, stars, planets, satellites, and galaxies currently overhead from anywhere on Earth. Highly praised and the winner of a 2010 Apple Design Award, the latest update allows users to enjoy unprecedented eye candy and interactivity of the star map, achieved with the new camera and high resolution of the new device.
Enter to win one of 10 free copies of this app for your iPhone. How?
In order to be entered into the giveaway drawing, just put your email address into the box at the bottom of this post (where it says “Enter the Giveaway”) before Monday, August 19, 2013. We’ll send you a confirmation email, so you’ll need to click that to be entered into the drawing.
An occultation of the star Mu Geminorum (to the upper right off the dark limb of the Moon) Photo by author.
The first in a cycle of challenging occultations of the bright star Spica for northern hemisphere observers begins this coming Monday on August 12th.
Watching a bright star or planet wink out on the dark limb of the Moon can be an amazing event to witness. It’s an abrupt “now you see it, now you don’t” event in a universe which often seems to move at an otherwise glacial pace. And if the event grazes the limb of the Moon, an observer may see a series of winks as the starlight streams through the lunar valleys.
Close companion stars have been discovered during occultations, and astronomers even used a series of occultations of radio source 3C 273 in 1962 to pin down the position of the first quasar.
An occultation occurs when one object passes in front of another as seen from the observer’s vantage point. The term has its hoary roots back in a time when astronomy was intertwined with its pseudoscience ancestor of astrology. Even today, I still get funny looks from non-astronomy friends when I use the term occultation, as if it just confirms their suspicions of the arcane arts that astronomers really practice in secret.
But back to reality-based science. At an apparent magnitude of +1.1, Spica is the 3rd brightest star that the Moon can occult along its five degree path above and below the plane of the ecliptic. It’s also one of only four stars brighter than +1.4 magnitude on the Moon’s path. The others are Antares (magnitude +1.0), Regulus (magnitude +1.4), and Aldebaran (magnitude +0.8). All of these are bright enough to be visible on the lunar limb through binoculars or a telescope in the daytime if conditions are favorable.
It’s interesting to note that this situation also changes over time due to the precession of the equinoxes. For example, the bright star Pollux was last occulted by the Moon in 117 BC, but cannot be covered by the Moon in our current epoch.
Spica is currently in the midst of a cycle of 21 occultations by our Moon. This cycle started in July 25th, 2012 and will end in January 2014.
Spica is a B1 III-IV type star 10 times the mass of the Sun. At 260 light years distant, Spica is one of the closest candidates to the Earth along with Betelgeuse to go supernova. Now, THAT would make for an interesting occultation! Both are safely out of the ~100 light year distant “kill zone”.
What follows are the circumstances for the next four occultations of Spica by the Moon. The times are given for closest geocentric conjunction of the two objects. Actual times of disappearance and reappearance will vary depending on the observer’s location. Links are provided for each event which include more info.
Looking westward 30 minutes after sunset for North American viewers on the night of August 12th. (Created by the Author using Starry Night).
First up is the August 12th occultation of Spica, which favors Central Asia and the Asian Far East. This will occur late in the afternoon sky around 09:00 UT and prior to sunset. The waxing crescent Moon will be six days past New phase. North American observers will see the Moon paired five degrees from Spica with Saturn to the upper left on the evening of August 12th.
The footprint for the September 8th occultation of Spica by the Moon. Note that the broken line indicates where the occultation will take place in the daytime sky. ( Credit: Occult 4.1.0.2)
Next is the September 8th daytime occultation of Spica for Europe, the Middle East and northern Africa around ~15UT. This will be a challenge, as the Moon will be a waxing crescent at only 3 days past New. Observers in the Middle East will have the best shot at this event, as the occultation occurs at dusk and before moonset. Note that the Moon also occults Venus six hours later for Argentina and Chile.
Looking to the east the morning of November 2nd for North American observers. (Created by the author using Stellarium).
After taking a break in October (the occultation of October 5 occurs only 23 hours after New and is unobservable), the Moon again occults Spica on November 2nd for observers across Europe & Central Asia. This will be a difficult one, as the Moon will be only 20 hours from New and a hybrid solar eclipse that will cross the Atlantic and central Africa. It may be possible to lock on to the Moon and track it up into the daylight, just be sure to physically block the rising Sun behind a building or hill!
The occultation footprint of Spica by the Moon for November 29th, 2013. (Reproduced from the Astronomical Almanac online and produced by the U.S. Naval Observatory and H.M. Nautical Almanac Office).
Finally, the Moon will occult Spica for North American observers on November 29th centered on 17:03 UT. This will place the event low in the nighttime sky for Alaskan observers. It’ll be a bit more of a challenge for Canadian and U.S. observers in the lower 48, as the Moon & Spica will be sandwiched between the Sun and the western horizon in the mid-day sky. As an added treat, comet C/2012 S1 ISON will reach perihelion on November 28th, just 20 hours prior and will be reaching peak brilliance very near the Sun.
And as an added bonus, the Moon will be occulting the +2.8 star Alpha Librae (Zubenelgenubi) on August 13th for central South America.
All of these events are challenges, to be sure. Viewers worldwide will still catch a close night time pairing of the Moon and Spica on each pass. We’ve watched the daytime Moon occult Aldebaran with binoculars while stationed in Alaska back in the late 1990’s, and can attest that such a feat of visual athletics is indeed possible.
And speaking of which, the next bright star due for a series of occultations by the Moon is Aldebaran starting in 2015. After 2014, Spica won’t be occulted by the Moon again until 2024.
But wait, there’s more- the total eclipse of the Moon occurring on April 15th 2014 occurs just 1.5 degrees from Spica, favoring North America. This is the next good lunar eclipse for North American observers, and one of the best “Moon-star-eclipse” conjunctions for this century. Hey, at least it’ll give U.S. observers something besides Tax Day to look forward to in mid-April. More to come in 2014!
Did you know you can distinguish between stars and planets in the sky?
Stars twinkle, planets don’t.
Okay, that’s not actually correct. The stars, planets, even the Sun and Moon twinkle, all in varying amounts. Anything outside the atmosphere is going to twinkle.
If you’re feeling a little silly using the word twinkle over and over again, we can also use the scientific term: astronomical scintillation.
You can’t feel it, but you’re carrying the entire weight of the atmosphere on your shoulders. Every single square inch of your skin is getting pushed by 15 pounds of pressure. And even though astronomers need our atmosphere to survive, it still drives them crazy. As it makes objects in space so much harder to see.
Stars twinkle, I mean scintillate, because as light passes down through a volume of air, turbulence in the Earth’s atmosphere refracts light differently from moment to moment. From our perspective, the light from a star will appear in one location, then milliseconds later, it’ll be distorted to a different spot.
We see this as twinkling.
So why do stars appear to twinkle, while planets don’t?
Stars appear as a single point in the sky, because of the great distance between us and them. This single point can be highly affected by atmospheric turbulence. Planets, being much closer, appear as disks.
We can’t resolve them as disks with our eyes, but it still averages out as a more stable light in the sky.
Astronomers battle atmospheric turbulence in two ways:
First, they try to get above it. The Hubble Space Telescope is powerful because it’s outside the atmosphere. The mirror is actually a quarter the size of a large ground-based observatory, but without atmospheric distortion, Hubble can resolve galaxies billions of light-years away. The longer it looks, the more light it gathers.
Second, they try to compensate for it.
Some of the most sophisticated telescopes on Earth use adaptive optics, which distorts the mirror of the telescope many times a second to compensate for the turbulence in the atmosphere.
A beam from the Laser Star Guide on one of the VLT’s four Unit Telescopes helps to correct the blurring effect of Earth’s atmosphere before making observations (ESO/Y. Beletsky)Astronomers project a powerful laser into the sky, creating an artificial star within their viewing area. Since they know what the artificial star should look like, they distort the telescope’s mirror with pistons cancelling out the atmospheric distortion. While it’s not as good as actually launching a telescope into space, it’s much, much cheaper.
Now you know why stars twinkle, why planets don’t seem to twinkle as much, and how you can make all of them stop.
We have written many articles about stars here on Universe Today. Here’s an article that talks about a technique astronomers use to minimize the twinkle of the Earth’s atmosphere.
An organization called Uwingu is hoping to raise funds to help discover new extrasolar planets, and then reward those funders with naming rights, but so far, this policy hasn’t been adopted by the IAU.
