Space and astronomy news
With the latest Kepler space telescope exoplanet finding announced yesterday, the mighty planet hunter has now found 1,000 confirmed worlds — with about 3,000 more planetary candidates just waiting for confirmation.
The NASA observatory has found exoplanets of many sizes — smaller than Mercury, the size of our Moon, the size of Jupiter or larger, and in a couple of cases, Earth-sized worlds in the habitable regions of their stars. Below is a gallery of some of the observatory’s notable finds.
“By the Light of the Silvery Moon” goes the song. But the color and appearance of the Moon depends upon the particular set of eyes we use to see it. Human vision is restricted to a narrow slice of the electromagnetic spectrum called visible light.
With colors ranging from sumptuous violet to blazing red and everything in between, the diversity of the visible spectrum provides enough hues for any crayon color a child might imagine. But as expansive as the visual world’s palette is, it’s not nearly enough to please astronomers’ retinal appetites.
Since the discovery of infrared light by William Herschel in 1800 we’ve been unshuttering one electromagnetic window after another. We build telescopes, great parabolic dishes and other specialized instruments to extend the range of human sight. Not even the atmosphere gets in our way. It allows only visible light, a small amount of infrared and ultraviolet and selective slices of the radio spectrum to pass through to the ground. X-rays, gamma rays and much else is absorbed and completely invisible.
To peer into these rarified realms, we’ve lofting air balloons and then rockets and telescopes into orbit or simply dreamed up the appropriate instrument to detect them. Karl Jansky’s homebuilt radio telescope cupped the first radio waves from the Milky Way in the early 1930s; by the 1940s sounding rockets shot to the edge of space detected the high-frequency sizzle of X-rays. Each color of light, even the invisible “colors”, show us a new face on a familiar astronomical object or reveal things otherwise invisible to our eyes.
So what new things can we learn about the Moon with our contemporary color vision?
Radio: Made using NRAO’s 140-ft telescope in Green Bank, West Virginia. Blues and greens represent colder areas of the moon and reds are warmer regions. The left half of Moon was facing the Sun at the time of the observation. The sunlit Moon appear brighter than the shadowed portion because it radiates more heat (infrared light) and radio waves.
Submillimeter: Taken using the SCUBA camera on the James Clerk Maxwell Telescope in Hawaii. Submillimeter radiation lies between far infrared and microwaves. The Moon appears brighter on one side because it’s being heated by Sun in that direction. The glow comes from submillimeter light radiated by the Moon itself. No matter the phase in visual light, both the submillimeter and radio images always appear full because the Moon radiates at least some light at these wavelengths whether the Sun strikes it or not.
Mid-infrared: This image of the Full Moon was taken by the Spirit-III instrument on the Midcourse Space Experiment (MSX) at totality during a 1996 lunar eclipse. Once again, we see the Moon emitting light with the brightest areas the warmest and coolest regions darkest. Many craters look like bright dots speckling the lunar disk, but the most prominent is brilliant Tycho near the bottom. Research shows that young, rock-rich surfaces, such as recent impact craters, should heat up and glow more brightly in infrared than older, dust-covered regions and craters. Tycho is one of the Moon’s youngest craters with an age of just 109 million years.
Near-infrared: This color-coded picture was snapped just beyond the visible deep red by NASA’s Galileo spacecraft during its 1992 Earth-Moon flyby en route to Jupiter. It shows absorptions due to different minerals in the Moon’s crust. Blue areas indicate areas richer in iron-bearing silicate materials that contain the minerals pyroxene and olivine. Yellow indicates less absorption due to different mineral mixes.
Visible light: Unlike the other wavelengths we’ve explored so far, we see the Moon not by the light it radiates but by the light it reflects from the Sun.
The iron-rich composition of the lavas that formed the lunar “seas” give them a darker color compared to the ancient lunar highlands, which are composed mostly of a lighter volcanic rock called anorthosite.
Ultraviolet: Similar to the view in visible light but with a lower resolution. The brightest areas probably correspond to regions where the most recent resurfacing due to impacts has occurred. Once again, the bright rayed crater Tycho stands out in this regard. The photo was made with the Ultraviolet Imaging Telescope flown aboard the Space Shuttle Endeavour in March 1995.
X-ray: The Moon, being a relatively peaceful and inactive celestial body, emits very little x-ray light, a form of radiation normally associated with highly energetic and explosive phenomena like black holes. This image was made by the orbiting ROSAT Observatory on June 29, 1990 and shows a bright hemisphere lit by oxygen, magnesium, aluminum and silicon atoms fluorescing in x-rays emitted by the Sun. The speckled sky records the “noise” of distant background X-ray sources, while the dark half of the Moon has a hint of illumination from Earth’s outermost atmosphere or geocorona that envelops the ROSAT observatory.
Gamma rays: Perhaps the most amazing image of all. If you could see the sky in gamma rays the Moon would be far brighter than the Sun as this dazzling image attempts to show. It was taken by the Energetic Gamma Ray Experiment Telescope (EGRET). High-energy particles (mostly protons) from deep space called cosmic rays constantly bombard the Moon’s surface, stimulating the atoms in its crust to emit gamma rays. These create a unique high-energy form of “moonglow”.
Astronomy in the 21st century is like having a complete piano keyboard on which to play compared to barely an octave a century ago. The Moon is more fascinating than ever for it.
The Hubble Space Telescope has delivered an amazing near quarter-century of science from all over the universe. Even this year, it’s delivered results to think about: the shrinking Great Red Spot on Jupiter (see picture below), helping New Horizons hunt for flyby targets after Pluto, and enhancing our view of deep space.
But that didn’t come cheap. Four astronaut servicing missions (including one to fix a mirror that was launched with myopia) were required to keep the telescope going since 1990. Hubble has never been more scientifically productive, according to a recent NASA review, but a new article asks if Hubble is destined to die a fiery death when its orbit decays in the next eight to 10 years.
“NASA doesn’t have any official plans for upgrading the telescope, meaning its hardware will grow old and out-of-date in the coming years,” reads the article in Popular Science. “Without assistance, Hubble can’t maintain its orbit forever, and eventually Earth’s gravity will pull the telescope to a fiery death.”
That’s not to say NASA is going to abandon the cosmos — far from it. Besides NASA’s other space telescopes, the successor James Webb Space Telescope is planned to launch in 2018 to chart the universe in other wavelengths. But a review from April warns that ceasing operations of Hubble would not be prudent until James Webb is up, running, and doing its own work productively. That’s a narrow window of time considering Hubble is expected to work well until about 2020.
The Hubble Space Telescope senior review panel submitted a report on March that overall praised the observatory’s work, and which also talked about its potential longevity. As is, Hubble is expected to work until at least 2020, the review stated. The four science instruments are expected to be more than 85% reliable until 2021, and most “critical subsystems” should exceed 80% until that same year.
The report urges that experienced hands are kept around as the telescope degrades in the coming years, but points out that Hubble has backups that should keep the observatory as a whole going for a while.
There are no single-point failure modes on Hubble that could take down the entire observatory. It has ample redundancy. Planned mitigations for numerous possible sub-system failures or degraded performance have been developed in advance via the project’s Life-Extension Initiatives campaign. Hubble will likely degrade gracefully, with loss or degradation of individual science instrument modes and individual sub-system components.
In NASA’s response to the Senior Review for several missions (including Hubble), the agency said that the telescope has been approved (budgetarily speaking) until 2016, when an incremental review will take place. Further in the future, things get murky.
The just-tested Orion spacecraft won’t be ready to take crews until the mid-2020s, and so far (according to the Popular Science article) the commercial crew program isn’t expected to include a servicing mission.
According to STS-125 astronaut Michael Good, who currently serves in the Commercial Crew Program, the space agency isn’t looking into the possibility of using private companies to fix Hubble, but he says there’s always a chance that could happen. “One of the reasons we’re doing Commercial Crew is to enable this capability to get into lower Earth orbit,” says Good. “But it’s certainly in the realm of possibility.”
Much can happen in a decade — maybe a surge in robotic intelligence would make an automated mission more possible — but then there is the question of priorities. If NASA chooses to rescue Hubble, are there other science goals the agency would need to push aside to accomplish it? What is best? Feel free to leave your feedback in the comments.
Dreams of space are often tied to jet engines or solar sails or taking a ride on a rocketship. But it’s often quite efficient to do research from Earth, especially from the high reaches of the atmosphere where there are few molecules to get in the way of observations.
NASA wants to do more of this kind of astronomy with an airship — but at an extreme height of 65,000 feet (20 kilometers) for 20 hours. No powered-airship mission has managed to last past eight hours at this height because of the winds in that zone, but NASA is hoping that potential creators would be up to the challenge.
This isn’t a guaranteed mission yet. NASA has a solicitation out right now to gauge interest from the community, and to figure out if it is technically feasible. This program would be a follow-on to ideas such as SOFIA, a flying stratospheric telescope that the agency plans to defund in future budgets.
Their goal is to fly an airship with a 44-pound (20-kilogram) payload at this altitude for 20 hours. If a company is feeling especially able, it can even try for a more difficult goal: a 440-pound (200-kilogram) payload for 200 hours.
“We are seeking to take astronomy and Earth science to new heights by enabling a long-duration, suborbital platform for these kinds of research,” stated lead researcher Jason Rhodes, an astrophysicist at NASA’s Jet Propulsion Laboratory in California.
And why not just use a balloon? It comes down to communications, NASA says: “Unlike a balloon, which travels with air currents, airships can stay in one spot,” the agency states. “The stationary nature of airships allows them to have better downlink capabilities, because there is always a line-of-sight communication.”
If the prize goes forward, NASA is considering awarding $2 million to $3 million across multiple prizes. You can get more on the official request for information at this link.
Source: NASA
It’s a major mystery posed by our sister world.
Does the atmosphere of Venus possess upper atmospheric phenomena similar to the Earth, such as aurora or nightglow?
Now, a recent announcement out of the American Astronomical Society’s 46th annual meeting of the Division of Planetary Science being held this week in Tucson, Arizona has shed new light on the dilemma.
The discovery was announced on Wednesday, November 12th at the 46th AAS meeting and was made as a collaborative effort by researchers from New Mexico State University at Las Cruces, the Stanford Research Institute (SRI) International, the University of Colorado at Boulder, the University of Koln and University of Munich, Germany, the European Space and Technology Center in the Netherlands and the Institut de Recherche en Astrophysique et Planétologie, in France.
For the study, researchers observed Venus from December 2010 to July 2012 using the Astrophysical Research Consortium (ARC)Echelle Spectrograph and the ARC 3.5 metre telescope located at Apache Point near Sunspot, New Mexico.
Timing was crucial, as the Sun was coming off of a profound deep minimum through 2009 and just beginning to become active with the start of solar cycle #24. Observers were looking for activity along the 5577.3 angstrom wavelength known as the “oxygen green line.” Activity had not been seen at this wavelength on the nighttime side of Venus since 2004.
“These are intriguing results, suggesting that it is possible to have aurora on non-magnetic planets,” said Candace Gray, Astronomer and NASA Earth and Space Science Fellow at Las Cruces and lead researcher in the study. “On Venus, this green line has been seen only intermittently.”
Earth is the oddball among the terrestrial planets in the inner solar system with its robust magnetic field. On Earth, aurorae occur when said field captures charged particles ejected from the Sun and funnels them in towards the poles. Events seen in the study tended to drop 140 to 120 kilometres in altitude in the Venusian atmosphere, highly suggestive of auroral activity seen in the ionosphere of Earth.
Researchers were fortunate during one of the recent runs at Apache Point that the Sun kicked off a coronal mass ejection that headed Venus’s way. During the July 2012 solar storm, the team detected one of the brightest green line emissions that had ever been detected by observers on Earth.
This demonstrates that perhaps, a magnetic field is optional when it comes to auroral activity, at least in the case of the planet Venus. Located only 0.7 astronomical units (108.5 million kilometres) from the Sun, our tempestuous star actually wraps the planet with its very own magnetotail.
Researchers are also looking to compare their results with observations from the European Space Agency’s Venus Express orbiter which arrived at the planet on April 2006.
“Currently, we are using observations from VIRTIS on Venus Express to try and detect the green line,” Gray told Universe Today. “We had coordinated ground based observations with them this past February, and we detected the green line from the ground when they were observing the night side limb. Additionally, we are using the Electron Spectrometer and ASPERA-4 to observe how the electron energy and density changes in the atmosphere after coronal mass ejection impacts.”
This also raises the interesting possibility that NASA’s MAVEN spacecraft — which recently arrived in orbit around Mars — might just detect similar activity in the tenuous Martian atmosphere as well. Like Venus, the Red Planet also lacks a global magnetic field.
Could this glow be connected with spurious sightings of the “Ashen Light of Venus” that have cropped up over the centuries?
Of course, ashen light, also known as Earthshine on the dark limb of the Moon, is easily explained as sunlight reflected back from the Earth. Moonless Venus, however, should be ashen light free.
“The green line emission that we see is brightest on the limb (edge) of the planet,” Gray told Universe Today. “We’re sure that there is emission all along the nightside, but because of the optical depth, it appears much brighter on the limb of the planet. I think it would be too faint to detect with the naked eye.”
Nightglow has been a leading suspect for ashen light on the Venusian nightside, and a similar green line emission detection rivaling the 2012 event was made by Tom Slanger using the Keck I telescope 1999.
Other proposed suspects over the centuries for ashen light on Venus include lightning, volcanism, light pollution (!) from Venusian cities, or just plain old observer error.
Certainly, future observations are needed to cinch the solar activity connection.
“We will likely observe Venus again from Apache Point the next time Venus is visible to us in June 2015,” Gray told Universe Today. “We will continue looking at Venus Express observations until the craft dies in the atmosphere.”
Venus can currently be seen crossing through the field of view of SOHO’s LASCO C3 camera. After spending most of 2014 in the dawn sky, Venus will emerge from behind the Sun low in the dusk to head towards greatest elongation in the evening sky on June 6th, 2015. And from there, Venus will once again slender towards a crescent, presenting its nightside towards Earth, and just perhaps, continuing to present a lingering mystery of modern astronomy.
One doesn’t take two cubesats and rub them together to make static electricity. Rather, you send them on a brief space voyage to low-earth orbit (LEO) and space them apart some distance and voilà, you have a telescope. That is the plan of NASA’s Goddard Space Flight Center engineers and also what has been imagined by several others.
Cubesats are one of the big crazes in the new space industry. But nearly all that have flown to-date are simple rudderless cubes taking photos when they are oriented correctly. The GSFC engineers are planning to give two cubes substantial control of their positions relative to each other and to the Universe surrounding them. With one holding a telescope and the other a disk to blot out the bright sun, their cubesat telescope will do what not even the Hubble Space Telescope is capable of and for far less money.
The 1U, the 3U, the 9U – these are all cubesats of different sizes. They all have in common the unit size of 1. A 1U cubesat is 10 x 10 x 10 centimeters cubed. A cube of this size will hold one liter of water (about one quart) which is one kilogram by weight. Or replace that water with hydrazine and you have very close to 1 kilogram of mono-propellent rocket fuel which can take a cubestat places.
GSFC aerospace engineers, led by Neerav Shah, don’t want to go far, they just want to look at things far away using two cubesats. Their design will use one as a telescope – some optics and a good detector –and the other cubesat will stand off about 20 meters, as they plan, and function as a coronagraph. The coronagraph cubesat will function as a sun mask, an occulting disk to block out the bright rays from the surface of the Sun so that the cubesat telescope can look with high resolution at the corona and the edge of the Sun. To these engineers, the challenge is keeping the two cubesats accurately aligned and pointing at their target.
Only dedicated Sun observing space telescopes such as SDO, STEREO and SOHO are capable of blocking out the Sun, but their coronagraphs are limited. Separating the coronagraph farther from the optics markedly improves how closely one can look at the edge of a bright object. With the corongraph mask closer to the optics, more bright light will still reach the optics and detectors and flood out what you really want to see. The technology Shah and his colleagues develop can be a pathfinder for future space telescopes that will search for distant planets around other stars – also using a coronagraph to reveal the otherwise hidden planets.
The engineers have received a $8.6-million investment from the Defense Advanced Research Project Agency (DARPA) and are working in collaboration with the Maryland-based Emergent Space Technologies.
The challenge of GSFC engineers is giving two small cubesats guidance, navigation, and control (GN&C) as good as any standard spacecraft that has flown. They plan on using off-the-shelf technology and there are many small and even large companies developing and selling cubesat parts.
This is a sorting out period for the cubesat sector, if you will, of the new space industry. Sorting through the off-the-shelf components, the GSFC engineers led by Shah will pick the best in class. The parts they need are things like tiny sun sensors and star sensors, laser beams and tiny detectors of those beams, accelerometers, tiny gyroscopes or momentum wheels and also small propulsion systems. The cubesat industry is pretty close to having all these ready as standard issue. The question then is what do you do with tiny satellites in low-Earth orbit (LEO). Telescopes for earth-observing are already making headway and scopes for astronomy are next. There are also plans to venture out to interplanetary space with tiny and capable cubesat space probes.
Whether one can sustain a profit for a company built on cubesats remains a big question. Right now those building cubesats to customer specs are making a profit and those making the tiny picks and shovels for cubesats are making profits. The little industry may be overbuilt which in economic parlance might be only natural. Many small startups will fail. However, for researchers at universities and research organizations like NASA, cubesats have staying power because they reduce cost by their low mass and size, and the low cost of the components to make them function. The GSFC effort will determine how quickly cubesats begin to do real work in the field of astronomy. Controlling attitude and adding propulsion is the next big thing in cubesat development.
References:
A research team led by Caltech astronomers of Pasadena California have discovered an ultraluminous X-ray (ULX) source that is pulsating. Their analysis concluded that the source in a nearby galaxy – M82 – is from a rotating neutron star, a pulsar. This is the first ULX source attributed to a pulsar.
Matteo Bachetti of the Université de Toulouse in France first identified the pulsating source and is the lead author of the paper, “An ultraluminous X-ray source powered by an accreting neutron star” in the journal Nature. Caltech astronomer Dr. Fiona Harrison, the team leader, stated “This compact little stellar remnant is a real powerhouse. We’ve never seen anything quite like it. We all thought an object with that much energy had to be a black hole.”
What is most extraordinary is that this discovery places even more strain on theories already hard pressed to explain the existence of ultraluminous X-Ray sources. The burden falls on the shoulder of the theorists.
The source of the observations is the NuSTAR space telescope, a SMEX class NASA mission. It is a Wolter telescope that uses grazing incidence optics, not glass (refraction) or mirrors (reflection) as in visible light telescopes. The incidence angle of the X-rays must be very shallow and consequently the optics are extended out on a 10 meter (33 feet) truss. NuSTAR records its observations with a time stamp such as taking a video of the sky. The video recording in high speed is not in visible everyday light but what is called hard x-rays. Only gamma rays are more energetic. X-rays emanate from the most powerful sources and events in the Universe. NuStar observes in the energy range of X-Rays from 5 to 80 KeV (electron volt)while the famous Chandra space telescope observes in the .1 to 10 KeV range. Chandra is one NASA’s great space telescope, was launched by the Space Shuttle Columbia (STS-93) in 1999. Chandra has altered our view of the Universe as dramatically as the first telescope constructed by Galileo. NuSTAR carries on the study of X-rays to higher energies and with greater acuity.
ULX sources are rare in the Universe but this is the first pulsating ULX. After analysis, they concluded that this is not a black hole but rather its little brother, a spinning neutron star as the source. More specifically, this is an accreting binary pulsar; matter from a companion star is being gravitationally attracted by and accreting onto the pulsar.
Take a neutron star and spin it up to anywhere from 700 rotations per second to a mere one rotation every 10 seconds. Now you have a neutron star called a pulsar. Spinning or not, these are the remnants of supernovae, stellar explosions that can outshine a galaxy of 300 billion stars. Just one teaspoon of neutron star material weighs 10 million tons (9,071,847,400 kg). That is the same weight as 900 Great Pyramids of Giza all condensed to one teaspoon. As incredible a material and star that a neutron star is, they were not thought to be the source of any ultraluminous X-Ray sources. This view has changed with the analysis of observations by this research team utilizing NuSTAR. The telescope name – NuSTAR – stands for Nuclear Spectroscopic Telescope Array.
There is nothing run of the mill about black holes. Dr. Stephen Hawking only conceded after 25 years, in 2004 (the Thorne-Hawking Bet) that Black Holes exist. And still today it is not absolutely certain. Recall the Universe Today weekly – Space Hangout on September 26 – “Do Black Holes exist?” and the article by Jason Major, “There are no such things as Black Holes.”
Pulsars stars are nearly as exotic as black holes, and all astronomers accept the existence of these spinning neutron stars. There are three final states of a dying star. Stars like our Sun at the end of their life become very dense White Dwarf stars, about the size of the Earth. Neutron stars are the next “degenerate” state of a dying exhausted star. All the electrons have merged with the protons in the material of the star to become neutrons. A neutron star is a degenerate form of matter effectively made up of all neutron particles. Very dense, these stars are really small, the size of cities, about 16 miles in diameter. The third type of star in its final state is the Black Hole.
A spinning neutron star creates a magnetic field, the most powerful of such fields in the Universe. They are like a dipole of a bar magnet and because of how magnetic fields confine the hot gases – plasma – of the neutron star, constant streams of material flow down and light streams out from the magnetic poles.
Recently, the Earth has had incredible northern lights, aurora. These lights are also from hot gases — a plasma — at the top of our atmosphere. Likewise, hot energetic particles from the Sun are funneled down into the magnetic poles of the Earth’s field that creates the northern lights. For spinning neutron stars – pulsars – the extreme light from the magnetic poles are like beacons. Just like our Earth, the magnetic poles and the spin axis poles do not coincide. So the intense beacon of light will rotate around and periodically point at the Earth. The video of the first illustration describes this action.
The light beacons from pulsars are very bright but theory, until now, has been supported by observations. No ultraluminous X-ray sources should be pulsars. The newly discovered pulsar is outputting 100 times more energy than any other. Discoveries like the one by these astronomers utilizing NuSTAR is proof that there remains more to discover and understand and new telescopes will be conceived to help resolve questions raised by NuSTAR or Chandra.
Further reading: JPL
As the Chinese proverb says, “May you live in interesting times,” and while the promise of Comet ISON dazzling observers didn’t exactly pan out as hoped for in early 2014, we now have a bevy of binocular comets set to grace evening skies for northern hemisphere observers. Comet 2012 K1 PanSTARRS has put on a fine show, and comet C/2014 E2 Jacques has emerged from behind the Sun and its close 0.085 AU passage near Venus and has already proven to be a fine target for astro-imagers. And we’ve got another icy visitor to the inner solar system beating tracks northward in the form of Comet C/2013 V5 Oukaimeden, and a grand cometary finale as comet A1 Siding Spring brushes past the planet Mars. That is, IF a spectacular naked eye comet doesn’t come by and steal the show, as happens every decade or so…
Anyhow, here’s a rapid fire run down on what you can expect from three of these binocular comets that continue to grace the twilight skies this Fall.
(Note that mentions of comets “passing near” a given object denote conjunctions of less than an angular degree of arc unless otherwise stated).
C/2014 E2 Jacques:
Discovered by amateur astronomer Cristovao Jacques on March 13th of this year from the SONEAR Observatory in Brazil, Comet E2 Jacques has been dazzling observers as it passed 35 degrees from the north celestial pole and posed near several deep sky wonders as it transited the constellation of Cassiopeia.
Mid-September finds Jacques 55 degrees above the NE horizon at dusk for northern hemisphere viewers in the constellation Cygnus. It then races southward parallel to the galactic equator, keeping in the +7th to +8th magnitude range before dropping down below +10th magnitude in late October. After this current passage through the inner solar system, Comet Jacques will be on a shortened 12,000 year orbit.
-Brightest: Mid-August at +6th magnitude.
-Perihelion: July 2nd, 2014 (0.66 AU).
-Closest to Earth: August 28, 2014 (0.56 AU).
Some key upcoming dates:
Sep 10: Passes the +3.9 magnitude star Eta Cygni.
Sep 14: Passes near the famous optical double star Albireo and crosses into the constellation of Vulpecula.
Sep 16: Passes in front of the +4.4 magnitude star Alpha Vulpeculae.
Sep 20: Crosses the Coathanger asterism.
Sep 21: Crosses into the constellation Sagitta.
Sep 24: Crosses into Aquila.
Oct 5: Crosses the galactic plane.
Oct 14: passes near the +7.5 magnitude open cluster NGC 6755.
Oct 15: Drops back below +10th magnitude?
C/2013 V5 Oukaïmeden
Pronounced Ow-KAY-E-Me-dah, (yes, it’s a French name, with a very metal umlaut over the “ï”!) comet C/2013 V5 Oukaïmeden was discovered by the Moroccan Oukaïmeden Sky Survey (MOSS) located in the Atlas Mountains in Morocco. After completing a brief dawn appearance in early September, the comet moves into the dusk sky and starts the month of October located 38 degrees east of the Sun at about 14 degrees above the southwestern horizon as seen from latitude 30 degrees north at sunset. Southern hemisphere observers will continue to have splendid dawn views of the comet through mid-September at its expected peak. Comet Oukaïmeden is currently at +8th magnitude “with a bullet” and is expected to top out +6th magnitude in late September shortly before perihelion and perhaps remain a binocular object as it crosses the constellation Libra in October.
And its also worth noting that as comet A1 Siding Spring (see below) makes a close physical pass by Mars on October 19th, Comet Oukaïmeden makes a close apparent pass by Saturn as seen from our Earthly vantage point the evening before! To be sure, the dusk apparition of Comet Oukaïmeden will be a tough one, but if you can track down these bright guidepost objects listed below, you’ll have a chance at spying it.
-Brightest: Mid-September.
-Perihelion: September 28th, 2014 (0.63 AU from the Sun).
-Closest to Earth: September 16th, 2014 (0.48 AU).
Some key upcoming dates:
Sep 10 through Oct 4: Threads across the borders of the constellations Hydra, Pyxis, Antlia and Centaurus.
Sep 18: Passes near the +3.5 magnitude star Xi Hydrae.
Sep 19: Passes near the +4.3 magnitude star Beta Hydrae.
Sep 25: Passes 1.5 degrees from the +8th magnitude Southern Pinwheel Galaxy M83.
Oct 1: Passes in front of the +10.2 globular cluster NGC 5694.
Oct 3: Passes into Libra.
Oct 11: Passes near the +8.5 magnitude globular cluster NGC 5897.
Oct 16: Crosses the ecliptic plane northward.
Oct 18: Passes less than two degrees from Saturn.
Oct 25: Passes less than a degree from the 2 day old Moon and the +3.9 magnitude star Gamma Librae.
C/2013 A1 Siding Spring
This comet was discovered on January 3rd, 2013 from the Siding Spring observatory in Australia, and soon caught the eye of astronomers when it was discovered that it would make a nominal pass just 139,000 kilometres from Mars on October 19th.
As seen from the Earth, Comet A1 Siding Spring has just broken 10th magnitude and vaults up towards the planet Mars low to the southwest at dusk this Fall for northern hemisphere observers. A1 Siding Spring is expected to top out at +8th magnitude this month before its Mars encounter, and is on a one million year plus orbit.
-Brightest: Early to Mid-September.
-Perihelion: October 25th, 2014.
-Closest to Earth: October 28th, 2014 (1.4 AU).
Some key upcoming dates:
Sep 17: Passes into the constellation Telescopium.
Sep 20: Passes near the +8.5 magnitude globular NGC 6524.
Sep 21: Passes into the constellation Ara.
Sep 22: Passes the +3.6 magnitude star Beta Arae.
Sep 25: Crosses into Scorpius.
Sep 30: Passes the +3 magnitude star Iota Scorpii.
Oct 3: Passes near the +7.2 magnitude globular NGC 6441.
Oct 5: Passes 2 degrees from Ptolemy’s cluster M7.
Oct 8: Passes in front of the Butterfly cluster M6.
Oct 10: Crosses the galactic plane.
Oct 11: Crosses into Ophiuchus.
Oct 19: Passes just 2’ arc minutes from Mars as seen from Earth.
Oct 22: Passes north of the ecliptic.
Oct 30: Drops back below +10th magnitude?
Key moonless windows for evening comet viewing as reckoned from when the Moon wanes from Full to New are: September 9th to September 24th and October 8th to the 23rd.
Looking for resources to find out just what these comets and others are up to? The COBS Comet Observers database is a great resource for recent observations, as is Seiichi Yoshida’s Weekly Comet page. For history and current info, Gary Kronk’s Cometography is also a great treasure trove to delve into, as are the Yahoo! Comet and Comet Observer mailing lists.
Be sure to check out these fine icy visitors to the inner solar system coming to a sky near you. We fully expect to see more outstanding images of these comets and more filling up the Universe Today Flickr forum!
What’s it like to spend a night at a huge telescope observatory? Jordi Busque recorded a brilliant timelapse of the Very Large Telescope (VLT) and the Atacama Large Millimeter/submillimeter Array (ALMA). What makes this video unique is not only the exotic location in Chile, but the use of sound in the area rather than music.
Continue reading “Amazing Video Timelapse Of Big Telescopes At Work In Chile”
It’s an engaging thought experiment.
What if Earth had multiple moons? Our world has one large natural satellite, just over a quarter the diameter, 1/50th the volume, and less than 1/80th the mass of our fair world. In fact, the Earth-Moon system has sometimes been referred to as a “binary planet,” and our Moon stands as the largest natural satellite of any planet — that is, if you subscribe to bouncing Pluto and Charon out of “the club” — in contrast to its primary of any moon in our solar system.
But what if we had two or more moons? And are there any tiny “moonlet” candidates lurking out there, awaiting discovery and perhaps exploration?
While historical searches for tiny secondary moons of the Earth — and even “moons of our Moon” — have turned up naught, the Earth does indeed capture asteroids as temporary moons and eject them back into solar orbit from time to time.
Now, a recent paper out of the University of Hawaii written in partnership with the SETI Institute and the Department of Physics at the University of Helsinki has looked at the possible prospects for the population of captured Near-Earth asteroids, and the feasibility of detecting these with existing and future systems about to come online.
The hunt for spurious moons of the Earth has a fascinating and largely untold history. Arthur Upgren’s outstanding book Many Skies devotes an entire chapter to the possible ramifications of an Earth with multiple moons… sure, more moons would be a bane for astrophotographers, but hey, eclipses and transits of the Sun would be more common, a definite plus.
In 1846, astronomer Frederic Petit announced the discovery of a tiny Earth-orbiting moon from Toulouse observatory. “Petit’s Moon” was said to orbit the Earth once every 2 hours and 44 minutes and reach an apogee of 3,570 kilometres and a perigee of just 11.4 (!) kilometres, placing it well inside the Earth’s atmosphere on closest approach.
A slightly more believable claim came from astronomer Georg Waltemath in 1898 for a moon 700 kilometres in size — he claimed it was, of course, a very dark body and not very easily visible — orbiting the Earth at about 2.5 times the distance of the Moon. Waltemath even made an announcement of his discovery, and claimed to have found a third moon of the Earth for good measure.
And a much more dubious claim came from the astrologer Walter Gornold in 1918 of a secondary moon, dubbed Lilith. Apparently, then (as now) astrologers never actually bothered to look at the skies…
Turns out, our large Moon makes a pretty good goaltender, ejecting —and sometimes taking a beating from — any tiny second moon hopeful. Of course, you can’t blame those astronomers of yore entirely. Though none of these spurious moons survived the test of observational verification, these discoveries often stemmed from early efforts to accurately predict the precise motion of the Moon. Astronomers therefore felt they were on the right track, looking for an unseen perturbing body.
Fast forward to the 21st century. Quasi-moons of the Earth, such as 3753 Cruithne, have horseshoe-shaped orbits and seem to approach and recede from our planet as both orbit the Sun. Similar quasi-moons of Venus have also been discovered.
And even returning space junk can masquerade as a moon of Earth, as was the case of J002E3 and 2010 QW1, which turned out to be boosters from Apollo 12 and the Chinese Chang’e-2 missions, respectively.
What modern researchers are looking for are termed Temporarily Captured Orbiters, or TCOs. The study notes that perhaps an average of a few dozen asteroids up to 1 to 2 metres in size are in a “steady state” population that may be orbiting the Earth at any given time on an enter, orbit, and eject sort of conveyor belt. Estimates suggest that a large 5 to 10 metre asteroid is captured every decade so, and a 100 metre or larger TCO is temporarily captured by the Earth every 100,000 years. The study also estimates that about 1% occasionally hit the Earth. And though it wasn’t a TCO, the ability to detect an Earthbound asteroid before impact was demonstrated in 2008 with the discovery of 2008 TC3, less than 24 hours prior to striking in the Sudanese desert.
“There are currently no projects that are solely looking for minimoons at this time,” lead researcher Bryce Bolin of the University of Hawaii told Universe Today. “There are several surveys, such as PanSTARRS, the Catalina Sky Survey and the Palomar Transit Factory that are currently in operation that have the capability of discovering minimoons.”
We’re getting better at this hazardous asteroid detection business, that’s for sure. The researchers modeled paths and orbits for TCOs in the study, and also noted that collections may “clump” at the anti-sunward L2 opposition point, and the L1 sunward point, with smaller distributions located at the east and west quadrature points located 90 degrees on either side of the Earth. The L2 point in particular might make a good place to start the search.
Ironically, systems such as LINEAR and PanSTARRS may have already captured a TCO in their data and disregarded them in their quest for traditional Near Earth Objects.
“Surveys such as PanSTARRS/LINEAR utilize a filtration process to remove artifacts and false positives in the data as it gets processed through the data pipeline,” Researcher Bryce Bolin told Universe Today. “A common method is to apply a rate of motion cut… this is effective in eliminating many artifacts (which) tend to have a rate of motion as measured by the pipeline which is very high.”
Such systems aren’t always looking for fast movers near Earth orbit that can produce a trail or streak which may reassemble space junk or become lost in the gaps over multiple detection devices. And speaking of which, researchers note that Arecibo and the U.S. Air Force’s Space Surveillance System may be recruited in this effort as well. To date, one definite TCO, named 2006 RH120 has been documented orbiting and departing from the vicinity of the Earth, and such worldlets might make enticing targets for future manned missions due to their relatively low Delta-V for arrival and departure.
PanSTARRS-2 saw first light last year in 2013, and is slated to go online for full science operations by the end of 2014. Eventually, the PanSTARRS system will employ four telescopes, and may find a bevy of TCOs. The researchers estimate in the study that a telescope such as Subaru stands a 90% chance of nabbing a TCO after only five nights of dedicated sweeps of the sky.
Finally, the study also notes that evidence miniature moonlets orbiting Earth may lurk in the all sky data gathered by automated cameras and amateur observers during meteor showers. Of course, we’re talking tiny, dust-to-pebble sized evidence, but there’s no lower limit as to what constitutes a moon…
And so, although moons such a “Lilith” and “Petit’s Moon” belong to the annuals of astronomical history, temporary “minimoons” of Earth are modern realities. And as events such as Chelyabinsk remind us, it’s always worthwhile to hunt for hazardous NEOs (and TCOs) that may be headed our way. Hey, to paraphrase science fiction author Larry Niven: unlike the dinosaurs, we have a space program!
Read more about the fascinating history of moons that never were and more in the classic book The Haunted Observatory.