Universe Today

October 8, 2013December 23, 2015 by David Dickinson

A Fine Pair of Lunar Occultations for North America This Weekend

Pi Sagittarii moments before it was occulted by the Moon on August 10th, 2011. (Photo by Author).

Heads up, North American residents: our Moon is about to blot out two naked eye stars on Friday and Saturday night.

Such an event is known as an occultation, an astronomical term that has its hoary roots in astronomy’s pseudoscience ancestor of astrology. An occultation is simply when one astronomical body passes in front of another from our line of sight. There’s nothing quite like watching a star disappear on the dark limb of the Moon. In a universe where events often transpire over periods of time longer than a human life span, occultations are abrupt affairs to witness.

Close double stars have also been teased out of occultation data, winking out in a quick, step-wise fashion. If an occultation such as the two this weekend occurs while the Moon is waxing towards Full, we get the added advantage of watching the action on the leading dark limb of the Moon during convenient early evening hours.

Beta Capricorni on the dark limb of the Moon Saturday night. (Created by the author using Starry Night).

First up is the occultation of the +3.9^th magnitude star Rho Sagittarii on Friday night, October 11^th. Central conjunction for this occultation occurs at 00:40 Universal Time (UT) early on the morning of the 12^th. The Moon will be at a 51% illuminated waxing gibbous phase, having passed First Quarter just prior to the start of the occultation at 7:02 PM EDT/23:02 UT on the 11^th. The sunset terminator line at the start of the occultation will bisect the central U.S., and observers east of the Mississippi will get to witness the entire event. The southern graze line will cross Cuba and Guatemala. Note that the Moon will also pass its most southern declination for this lunation just two days prior on October 9^th at 23:00 UT/7:00 PM EDT, at a declination of -19.6 degrees. This is one of the Moon’s most southern journeys for 2013, meaning that it will still ride fairly far to the south in the sky during this weekend’s occultations.

The occultation of Rho Saggitarii by the Moon for the night of October 11th. (rendered using Occult 4.1.02 software). — The occultation of Rho Sagittarii by the Moon for the night of October 11th. the dashed line indicates where the occultation will occur in the daytime; east of this region, the occultation occurs after sunset. (rendered using Occult 4.1.02 software).

Rho Sagittarii is an F-type star 122 light years distant. Stick around until February 23^rd, 2046, and you’ll get to see an even rarer treat, when the planet Venus occults the very same star. Just south of the Rho Sagittarii pair lies the region from which the Wow! Signal was detected in 1977.

The Moon moves at an average speed of just over a kilometre a second in its orbit about the Earth, and traverses roughly the apparent distance of its angular size of 30’ in one hour. The duration of occultations as seen from their center line take about an hour from ingress to egress, though its much tougher to watch a star reappear on the bright limb of the Moon!

And the night of Saturday, October 12^th finds the 62% illuminated waxing gibbous Moon occulting an even brighter star across roughly the same region. The star is +3.1 magnitude Beta Capricorni, which also goes by the Arabic name of Dabih, meaning “the butcher.” Dabih is also an interesting double star with a +6^th magnitude component 3.5’ away from the +3^rd magnitude primary. Dabih is an easy split with binoculars, and it will be fun to watch the two components pass behind the Moon Saturday night. This occultation also occurs the night of October 12^th which is traditionally Fall Astronomy Day. If you’re hosting a star party this coming Saturday night, be sure to catch the well-timed occultation of Beta Capricorni! The central conjunction for this event occurs at 01:27 UT on the morning of the 13^th, and North American observers east of the Rockies will get to see the entire event.

The occultation footprint of Beta Capricorni for the night of October 12th. (Rendered using Occult 4.1.0.2 software).

Beta Capricorni is 328 light years distant, putting the physical separation of the B component at about a third of a light year away from the primary star at 21,000 astronomical units distant. “Beta B” thus takes about 700,000 years to orbit its primary! It’s also amazing to think that those fusion-born photons took over three centuries to get here, only to be rudely “interrupted” by the bulk of our Moon in the very last second of their journey.

And be sure to keep an eye on the primary star as it winks out, as it’s a known spectroscopic triple star with unseen companions in respective 9 and 1374 day orbits. Dabih may just appear to “hang” on the jagged lunar limb as those close companions wink out in a step-wise fashion.

Both occultations are bright enough to watch with the naked eye, although a standard set of 10x 50 binoculars will provide a fine view. The ingress of an occultation is also an excellent event to catch on video, and if you’ve got WWV radio running audio in the background, you can catch the precise time that the star disappears from your locale.

Note: WWV radio is still indeed broadcasting through the ongoing U.S. government shutdown, though they’re operated by NOAA & the NIST.

The International Occultation and Timing Association is always interested in reports of occultations carried out by amateur astronomers. Not only can this reveal or refine knowledge of close double stars, but a series of occultation observations from precisely known locations can map the profile of the lunar limb.

Be sure to catch both events this U.S. Columbus Day/Canadian Thanksgiving Day weekend, and send those pics in to Universe Today!

Precise timings for the ingress and egress of each lunar occultations for major North American cities can be found at the following pages:

– Rho Sagittarii

– Beta Capricorni

October 7, 2013December 23, 2015 by Nancy Atkinson

Astrophoto: Uranus at Opposition

Uranus, imaged from Italy on October 3, 2013, when the planet was at opposition. Credit and copyright: Giuseppe Petricca.

Last week, we asked if you were looking for an observing challenge: looking for planet Uranus when it reached opposition — where it is opposite the Sun the sky, meaning the planet rises as the Sun sets. Giuseppe Petricca from Italy took the challenge and ran with it. His skies over Sulmona, Abruzzo in Italy cleared, and not even 12 hours after the official time of opposition he got this shot using his new Toucam Pro II on a Newtonian 200/1000 on EQ5 unmotorized mount.

Nice!

Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.

October 7, 2013December 28, 2015 by Fraser Cain

Astronomy Cast Episode 316: Observational Versus Experimental Science

Sometimes you can do science by watching patiently, and sometimes you’ve just got to get your hands dirty with an experiment or two. These two methods have their advantages and disadvantages for revealing Nature’s secrets. Let’s talk about how and why scientists choose which path to go down.

Visit the Astronomy Cast Page to subscribe to the audio podcast!

We record Astronomy Cast as a live Google+ Hangout on Air every Monday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.

October 7, 2013December 23, 2015 by Bob King

Oct. 7, 1959 – Our First Look at the Far Side of the Moon

The first photo of the lunar far side taken by the Soviet (Russian) spacecraft Luna 3 on Oct. 7, 1959. The right three-quarters of the disk is the far side. A = Mare Moscoviense, B = Tsiolkovsky Crater with central peak, C = Mare Smythii (on the near side-far side border) and D = Mare Crisium (near side). This is the wide-angle view. Credit: Roscosmos

For millennia, human eyes have seen only one face of the moon. Put a dude from the Iron Age in a time machine and whisk him to 2013 and he’d see the same pattern of light lunar highlands punctuated by dark grey spots you see. Night after night after night.

*Telephoto view of the far side with Mare Smythii (Sea of Smyth) at left and bright crater Giordano Bruno at center. Credit: Roscosmos*

That all changed 54 years ago today when the Soviet Union’s Luna 3 probe opened its camera shutter and snapped the first pictures of the lunar far side. Though blurry and banded with electronic noise, everyone who saw them sat up in surprise. The backside barely resembled the front. It lacked in the familiar lunar maria, the dark spots that we instinctively patch together to form the face of the “man in the moon”.

Telephoto image of Mare Moscoviense is at upper right with Tsiolkovsky and its bright central peak at lower right. You can start to see vague outlines of many more craters in this view. Click for more historic photos. Credit: Roscosmos — Telephoto image of Mare Moscoviense is at upper right with Tsiolkovsky and its bright central peak at lower right. You can begin to see vague outlines of many more craters in this picture. Click for more historic photos. Credit: Roscosmos

Only two dark ovals were seen, Mare Moscoviense (Sea of Moscow) and the lava-filled floor of the crater Tsiolkovsky, named for Konstantin Tsiolkovksy, the Russian rocket pioneer. The rest, which looks like dried paste, is jammed with craters and related the near side’s light-toned, cratered highlands. Both are remnants of the original lunar crust that solidified as the moon cooled after formation.

The dramatic difference between near side and far side shows up in this much more recent global map of the map made by Clementine Mission in 1994. The map is centered on the near side with its many lunar "seas" or maria. The far side trails off to the left and right of center. Mare Moscoviense is at upper right. Credit: NASA — The dramatic difference between near side and far side shows up in this much more recent global map of the map made by Clementine Mission in 1994. The map is centered on the near side with its many lunar “seas” or maria. The far side trails off to the left and right of center. Mare Moscoviense is at upper right. Credit: NASA

Darker areas or “seas” are more recent basaltic lavas that welled up to fill huge impact scars left by colliding asteroids. They contain iron-rich minerals from deep beneath the crust which make them less reflective, hence darker in comparison to the highlands.

Tidal locking results in the Moon rotating about its axis in about the same time it takes to orbit the Earth (left side). If the Moon didn't spin at all, then it would alternately show its near and far sides to the Earth while moving around our planet in orbit, as shown in the figure on the right. Credit: Wikipedia — Tidal locking results in the moon rotating about its axis in about the same time it takes to orbit the Earth (left side). If the Moon didn’t spin at all, then it would alternately show its near and far sides to the Earth while moving around our planet in orbit, as shown in the figure on the right. Credit: Wikipedia

The moon hides its back or far side through a neat trick – it rotates at the same rate as it revolves around the Earth. Normally, rotation would bring new features into view, but every little bit it turns, it moves an equal amount along its orbit, hiding what would otherwise be exposed. It’s called synchronous rotation or tidal locking. Most of the larger moons in the solar system are tidally locked to their planets. Jupiter’s four biggest and brightest moons are a great example.

*Luna 3 probe sent to the moon by the then Soviet Union. It held two cameras and its own film processing lab. Credit: NASA*

Equipped with both wide angle (200 mm) and telephoto (500 mm) lenses, Luna 3 took 29 pictures covering about 70 percent of the far side during its loop around the moon. The first picture was shot from 39,500 miles away (63,500 km), the last taken 40 minutes later from 41,445 miles (66,700 km) distant. After the photo session was done, the probe passed over the moon’s north pole and headed back toward Earth.

Temperature and radiation-resistant film used for the photos was automatically moved to an onboard processor where it was developed, fixed and dried. A cathode ray tube then shot a beam of light through the film and onto a photoelectric multiplier, a light-sensitive device that converted the different gradations of tone into electric signals which were then transmitted to Earth. Almost sounds like a fire brigade, but hey it worked!

High resolution photo map of the moon's far side imaged by NASA's Lunar Reconnaissance Orbiter. Mare Moscoviense lies at upper left and Tsiolkovsky at lower left. Click for a hi res image. Credit: NASA — High resolution photo map of the moon’s far side imaged by NASA’s Lunar Reconnaissance Orbiter. Mare Moscoviense lies at upper left and Tsiolkovsky at lower left. Click for a hi res image. Credit: NASA

So what’s the reason for the moon’s split personality? We know the far side crust is 50 miles (80 km) thick versus 37 miles (60 km) for the near side. A thicker far side crust may have prevented magma from reaching and flooding the surface as they did on the near side. Heat released by the decay of radioactive elements also may play a role. NASA’s Lunar Prospector probe found more on the near side, where they may have encouraged the formation of hot magmas that eventually found their way to the surface.

What caused the fascinating asymmetry is unknown, but it may have to do with the slowing of the moon’s rotation into its present tidally-locked state under the heavy hand of Earth’s dominating gravitational influence.

October 7, 2013December 23, 2015 by Elizabeth Howell

Mercury’s Resonant Rotation ‘Should Be Common’ In Alien Planets

A global view of Mercury, as seen by MESSENGER. Credit: NASA

Three to two. That’s the ratio of the time it takes Mercury to go around the sun (88 days) in relation to its rotation (58 days). This is likely due to the influence of the Sun’s immense gravity on the planet. A new study confirms that finding, while stating something even more interesting: other star systems could see the same type of resonance.

Hundreds of confirmed exoplanets have been found so far, many of them in very tight configurations, the authors said. “Mercury-like states should be common among the hundreds of discovered and confirmed exoplanets, including potentially habitable super-Earths orbiting M-dwarf [red dwarf] stars,” they added. “The results of this investigation provide additional insight into the possibilities of known exoplanets to support extraterrestrial life.”

Habitability, of course, depends on many metrics. What kind of star is in the system, and how stable is it? How far away are the planets from the star? What is the atmosphere of the planet like? And as this study points out, what about if one side of the planet is tidally locked to its star and spends most or all of its time with one side facing the starshine?

Additionally, the study came up with an explanation as to why Mercury remains in a 3:2 orbit in opposition to, say, the Moon, which always has one side facing the Earth. The study took into account factors such as internal friction and a tidal “bulge” that makes Mercury appear slightly misshapen (and which could slow it down even further.) Basically, it has to do with Mercury’s early history.

From Orbit, Looking toward Mercury's Horizon. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington — From Orbit, Looking toward Mercury’s Horizon. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

“Among the implications of the released study are, to name a few, a fast tidal spin-down, a relatively cold (i.e., not fully molten) state of the planet at the early stages of its life, and a possibility that the internal segregation and formation of the massive liquid core happened after Mercury’s capture into the resonance,” the press release added.

The results were presented today (Oct. 7) at the American Astronomical Society department of planetary sciences meeting held in Denver. A press release did not make clear if the study has been submitted for peer review or published.

Source: AAS Division of Planetary Sciences

October 7, 2013December 23, 2015 by Elizabeth Howell

Is That Planet Habitable? Look To The Star First, New Study Cautions

Artist’s impression of the deep blue planet HD 189733b, based on observations from the Hubble Space Telescope. Credit: NASA/ESA.

Finding Earth 2.0, in the words of noted SETI researcher Jill Tarter, is something a lot of exoplanet searchers are hoping for one day. They’re trying not to narrow down their search to Sun-like stars, but also examine stars that are smaller, like red dwarfs.

A new study, however, cautions that the X-ray environment of these dwarfs may give us false positives. They looked at Earth-mass planets in the neighborhood of four stars, such as GJ 667 (which has three planets that could be habitable), and concluded it’s possible for oxygen to reside in these planets even in the absence of life.

The work builds on a published paper in the Astrophysical Journal that argues that GJ 876, studied by the Hubble Space Telescope, could allow a hypothetical planet to have plenty of oxygen in its atmosphere, even without the presence of life.

This artist's conception shows the newly discovered super-Earth GJ 1214b, which orbits a red dwarf star 40 light-years from our Earth. Credit: Credit: David A. Aguilar, CfA — This artist’s conception shows the newly discovered super-Earth GJ 1214b, which orbits a red dwarf star 40 light-years from our Earth. Credit: Credit: David A. Aguilar, CfA

The researchers themselves, however, caution that the results are preliminary and there is a lot more to study before coming to a definitive conclusion.

For example: “The effects of stellar flares on the atmosphere of the hypothetical Earth-like planet around GJ 876 have not been considered in this work,” stated Kevin France, who is with the University of Colorado at Boulder and also a co-author.

“At this point, we do not have a sufficient understanding of the amplitude and frequency of such flares on older, low-mass exoplanet host stars to make predictions about their impact on the production of biomarker signatures.”

The report was presented at the American Astronomical Society division for planetary sciences meeting in Denver today (Oct. 7). It was not immediately clear from a press release if the newer study has been submitted for peer review.

Source: AAS Division for Planetary Sciences

October 7, 2013December 23, 2015 by Elizabeth Howell

This Cave Video Makes You Feel Like You’re On An Alien Planet

"Cavenauts" exploring an underground lake. Credit: ESA/V. Crobu

A few weeks ago, a bunch of astronauts went underground in Italy in the name of science and better finessing the techniques of running a space mission. A movie-style “preview” of their work plays in the video above.

You can see how jazzed the astronauts are about the mission. “It was like being on Mars,” one says. Another says this is inspiration to explore the solar system, because then you get to possibly see beautiful things such as what is right in front of them.

Better yet, there’s way more material where that movie came from. Check out the full playlist on YouTube.

October 7, 2013October 17, 2013 by Fraser Cain

Virtual Star Party – October 6, 2013

Another wonderful Virtual Star Party, this time with 6 astronomers broadcasting their view of the night sky live. We had amazing views of Saturn, the Ring Nebula, M27, and M17 the Swan Nebula (also known as the Lobster or Horseshoe Nebula). We also caught great views of NGC-896, NGC-869, and the M56 Cluster. Then we got some beautiful views of the Veil Nebula and discussed the benefits of image-stabilized binoculars.

This was also the first time were joined by Scott Ferguson, who delighted us with his dark sky views from the west coast of Florida. His views of the Pelican Nebula (NGC-6996) were gorgeous and unique.
Continue reading “Virtual Star Party – October 6, 2013”

October 6, 2013December 23, 2015 by Jason Major

Awesome Photo: Aurora, Airglow, City Lights and Shining Stars

Photo taken by ESA astronaut Luca Parmitano on Sept. 5, 2013 (ESA/NASA)

Italian astronaut Luca Parmitano shares a lot of fantastic photos taken from his privileged position 260 miles up aboard the Space Station, orbiting the planet 16 times a day. This is his latest, a stunning view of nighttime city lights spread out beneath a glowing dome of ghostly airglow and shimmering aurorae, with a backdrop of brightly shining stars. The dark silhouette of a solar array is in the foreground at right.

And in case you were wondering, yes, astronauts certainly can see stars while in space. A lot of them, in fact. (Except up there, they don’t twinkle… but they’re no less beautiful!)

“Every time we look into the sky and we admire the same stars, we share the same experience with all those who still know how to dream.”

– Luca Parmitano

Luca Parmitano is the first of ESA’s new generation of astronauts to fly into space. The current mission, Volare, is ESA’s fifth long-duration Space Station mission. During his six-month-long stay aboard the ISS, Luca has been conducting research for ESA and international partners as well as taken many photographs of our planet, sharing them on Twitter, Flickr, and the Volare mission blog.

See this and more photos taken by Luca on the Volare Flickr page here.

Image credit: ESA/NASA

October 6, 2013December 23, 2015 by Ken Kremer

LADEE Successfully Enters Lunar Orbit on Oct. 6 Amidst Government Shutdown

NASA’s LADEE lunar orbiter will firing its main engine on Oct. 6 to enter lunar orbit in the midst of the US government shutdown. Credit: NASA

NASA’s LADEE lunar orbiter will fire its main engine on Oct. 6 to enter lunar orbit in the midst of the US government shutdown. Credit: NASA
See the orbit insertion animation below[/caption]

Update Oct 6: LADEE fired its main engine this morning (Oct. 6) at 6:57 a.m. EDT and successfully achieved lunar orbit. Headline/story revised.

NASA’s trailblazing LADEE lunar spacecraft is set to ignite its main engine and enter lunar orbit on Sunday morning, Oct. 6 – if all goes well – following the spectacular Sept. 6 night launch from NASA’s Virginia spaceport.

And in a happenstance no one could have foreseen, the critical engine firing comes smack in the midst of the political chaos reigning in Washington D.C. that has shut down the US government, furloughed 97% of NASA’s employees, and temporarily threatened the upcoming launch of NASA’s next mission to Mars – the MAVEN orbiter.

However, orbital mechanics waits for no one!

A source indicated that LADEE (Lunar Atmosphere and Dust Environment Explorer) mission operations were continuing leading up to the engine burn.

But there will be virtually a complete news blackout and little public information released due to the legal requirements of the shutdown.

NASA websites, which are amongst the most heavily trafficked, as well as NASA TV have been shuttered during the shutdown and the press office is likewise furloughed.

So it was do or die for LADEE with the four minute long braking thruster firing set to start on Oct. 6 at 6:57 a.m. EDT (10:57 UTC), so that the couch sized spacecraft is captured by the Moon’s gravity.

Fortunately, LADEE was deemed “essential” and a small team of engineers is working right now at mission control at NASA’s Ames Research Center in California.

If the had burn failed, LADEE will swing by the moon with no hope of returning. And this is being accomplished with a skeleton crew thanks to the government shutdown.

Here’s a video animation of orbital capture at the moon:

Video caption: This video shows the LADEE lunar orbit capture scheduled to take place at 10:57 UTC on 6 Oct. 2013. The main view is an Earth centered perspective showing the effect of the Moon’s gravity on the orbit and then how a Lunar orbit looks from the Earth. The inset view shows the same trajectory from the perspective of the Moon.

Dubbed LOI-1 (Lunar Orbit Insertion burn 1),it is designed to begin with LADEE’s arrival at the Moon after three and a half orbits of the Earth. It will change the spacecrafts velocity by 329.8 meters/sec.

LOI-1 is the first of three main engine maneuvers and will place LADEE into a 24 hour retrograde orbit, with a periselene altitude of 590 km (369 mi).

LOI-2 follows on Oct. 9 to place LADEE into a 4 hour orbit with a 250 km (156 mi) periselene altitude.

Finally LOI-3 on Oct. 12 places LADEE into a roughly circular 250 km (156 mi) orbit that initiates a 30 day commissioning phase as well as experiments using the on-board Lunar Laser Communications Experiment (LLCD) before the start of the missions science phase.

LADEE thundered to space atop the maiden launch of the five stage Minotaur V rocket on Sept. 6, blazing a spectacular trail to orbit from a beachside launch pad at NASA’s Wallops Flight Facility in Virginia.

This magnificent view of NASA’s LADEE lunar orbiter launched on Friday night Sept 6, on the maiden flight of the Minotaur V rocket from Virginia was captured by space photographer Ben Cooper perched atop Rockefeller Center in New York City. Credit: Ben Cooper/Launchphotography.com

The blastoff was easily visible to tens of millions of thrilled spectators up and down the eastern seaboard stretching from Maine to the Carolinas as a result of crystal clear skies and the night time liftoff.

The LADEE liftoff at 11:27 p.m. EDT marked the first space probe of any kind ever launched beyond Earth orbit from NASA Wallops, as well as being the first planetary science mission ever launched from Wallops.

Launch of NASA’s LADEE lunar orbiter on Friday night Sept. 6, at 11:27 p.m. EDT on the maiden flight of the Minotaur V rocket from NASA Wallops, Virginia, viewing site 2 miles away. Antares rocket launch pad at left. Credit: Ken Kremer/kenkremer.com

Eventually the spacecraft will fly in a very low equatorial science orbit of about 50 kilometers (31 mi) altitude above the moon that will require considerable fuel to maintain. The science mission duration is approximately 100 days, limited by the amount of maneuvering fuel.

The 844 pound (383 kg) robot explorer was assembled at NASA’s Ames Research Center, Moffett Field, Calif., and is a cooperative project with NASA Goddard Spaceflight Center in Maryland.

It is equipped with a trio of science instruments whose purpose is to collect data that will inform scientists in unprecedented detail about the ultra thin lunar atmosphere, environmental influences on lunar dust and conditions near the surface.

The goal of the $280 Million mission is to gain a thorough understanding of long-standing unknowns about the tenuous atmosphere, dust and surface interactions that will help scientists understand other planetary bodies as well.

The probe is built on a revolutionary ‘modular common spacecraft bus’, or body, that could dramatically cut the cost of exploring space and also be utilized on space probes to explore a wide variety of inviting targets in the solar system.

“LADEE is the first in a new class of interplanetary exploration missions,” NASA Ames Director Pete Worden told Universe Today in an interview. “It will study the pristine moon to study significant questions.”

“This is probably our last best chance to study the pristine Moon before there is a lot of human activity there changing things.”

Stay tuned here for continuing LADEE news.

Ken Kremer

…………….

Learn more about LADEE, MAVEN, Curiosity, Mars rovers, Cygnus, Antares, SpaceX, Orion, the Gov’t shutdown and more at Ken’s upcoming presentations

Oct 8: “NASA’s Historic LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”& “Curiosity and MAVEN updates”; Princeton University, Amateur Astronomers Assoc of Princeton (AAAP), Princeton, NJ, 8 PM