Astronomy Archives

January 17, 2014December 23, 2015 by Shannon Hall

Enduring Quests and Daring Visions: NASA Lays Out a Roadmap for Astrophysics

An artist's concept of Kepler-69c, a super-Earth in the habitable zone of a sun-like star.

Three decades ago we were unaware that exoplanets circled other stars. We had just started talking about dark matter but remained blissfully ignorant of dark energy. The Hubble Space Telescope was still on the drawing board and our understanding of the life cycle of stars, the evolution of galaxies, and the history of the Universe was shaky.

But over the past three decades we have discovered thousands of exoplanets around other stars. We have mapped the life cycle of stars from their formation in beautiful stellar nurseries to their sometimes explosive deaths. We have seen deep into the history of the Universe allowing us to paint a picture of galaxies growing from mere shreds to the incredible spiral structures we see today. We now believe dark matter dominates the underlying framework of the Universe, while dark energy drives its accelerating expansion.

The amount of growth over the past three decades has been dramatic. To better access what the next three decades will bring, NASA has laid out a roadmap — a long-term vision for future missions — necessary to advance our understanding of the Universe.

In March 2013, the NASA Advisory Council/Science Committee assembled a group of astronomers who would determine the goals and aims of NASA for the next 30 years. The final product is this so-called roadmap officially titled “Enduring Quests Daring Visions — NASA Astrophysics in the Next Three Decades.”

The roadmap first notes three defining questions NASA should continue to pursue:
— Are we alone?
— How did we get here?
— How does the Universe work?

“Seeking answers to these age-old questions are enduring quests of humankind,” the roadmap states. “The coming decades will see giant strides forward in finding earthlike habitable worlds, in understanding the history of star and galaxy formation and evolution, and in teasing out the fundamental physics of the cosmos.”

In order to better address these questions, the roadmap defines three broad categories of time: the Near-Term Era, defined by missions that are currently flying or planned for this coming decade, the Formative Era, defined by missions that are designed and built in the 2020s, and the Visionary Era, defined by advanced missions for the 2030s and beyond.

A schematic of the next 30 years subdivided into three decades across the entire electromagnetic spectrum. Image Credit: NASA 2014

Are we alone?

The Near-Term Era’s goal is to develop a comprehensive understanding of the demographics of planetary systems. The Kepler mission has already supplied a plethora of information on hot planets orbiting close to their parent stars. The WFIRST-AFTA mission — a wide-field infrared survey planned to launch in 2024 — will compliment this by supplying information on cold and free-floating planets.

The Formative Era’s goal is to characterize the surfaces and atmospheres of nearby stars. This will allow us to move beyond characterizing planets as Earth-like in mass and radius to truly being Earth-like in planetary and atmospheric composition. A proposed mission that allows a large star-planet contrast will directly measure oxygen, water vapor, and other molecules in the atmospheres of Earth-like exoplanets.

The Visionary Era’s goal is to produce the first resolved images of Earth-like planets around other stars. The roadmap team hopes to identify continents and oceans on distant worlds using optical telescopes orbiting hundreds of kilometers apart.

How did we get here?

The Near-Term Era will use the James Webb Space Telescope to supply unprecedented views of protostars and star clusters. It will resolve nearby stellar nurseries and take a closer look at the earliest galaxies.

The Formative Era will trace the origins of planets, stars and galaxies across a spectrum of wavelengths. An infrared surveyor will resolve protoplanetary disks while an X-ray surveyor will observe supernova remnants and trace how these incredible explosions affected the evolution of galaxies. Gravitational wave detectors will untangle the complicated dance between galaxies and the supermassive black holes at their centers.

The Visionary Era will peer nearly 14 billion years into the past when ultraviolet photons from the first generation of stars and black holes flooded spaced with enough energy to free electrons. The James Webb Space Telescope will provide an extraordinary means to better view this threshold.

How does the Universe work?

The Universe is full of extremes. Conditions created in the first nanoseconds of cosmic time and near the event horizons of black holes cannot be recreated in the lab. But the Near-Term and Formative Era’s goals will be to measure the cosmos with such precision that scientists can probe the underlying physics of cosmic inflation and determine the exact mechanisms driving today’s accelerating expansion.

The Visionary Era may use gravitational wave detectors to detect space-time ripples produced during the early stages of the Universe or map the shadow cast by a black hole’s event horizon.

The past 30 years have shown a dramatic growth in knowledge with unimaginable turns. Even with such a detailed framework laid out for the next 30 years, it’s likely that many missions are currently beyond the edge of the present imagination. The most exciting results will be drawn from the questions we haven’t even thought to ask yet.

And as with any of the recent “roadmaps” that the various divisions throughout NASA have presented, the biggest question will be if the funding will be available to make these missions a reality.

Again, this 110-page read may be found here.

The roadmap team consists of Chryssa Kouveliotou (NASA/MSFC), Eric Agol (University of Washington), Natalie Batalha (NASA/Ames), Jacob Bean (University of Chicago), Misty Bentz (Georgia State University), Neil Cornish (Montana State University), Alan Dressler (The Observatories of the Carnegie Institution for Science), Scott Gaudi (Ohio State University), Olivier Guyon (University of Arizona/Subaru Telescope), Dieter Hartmann (Clemson University), Enectali Figueroa-Feliciano (MIT), Jason Kalirai (STScI/Johns Hopkins University), Michael Niemack (Cornell University), Feryal Ozel (University of Arizona), Christopher Reynolds (University of Maryland), Aki Roberge (NASA/GSFC), Kartik Sheth (National Radio Astronomy Observatory/University of Virginia), Amber Straughn (NASA/GSFC), David Weinberg (Ohio State University), Jonas Zmuidzinas (Caltech/JPL), Brad Peterson (Ohio State University) and Joan Centrella (NASA Headquarters).

January 16, 2014December 23, 2015 by Matthew Francis

Some Planet-like Kuiper Belt Objects Don’t Play “Nice”

Distribution of Kuiper belt objects (green), along with various other outer Solar System bodies, based on data from the Minor Planet Center. [Credit: Minor Planet Center; Murray and Dermott]

The Kuiper belt — the region beyond the orbit of Neptune inhabited by a number of small bodies of rock and ice — hides many clues about the early days of the Solar System. According to the standard picture of Solar System formation, many planetesimals were born in the chaotic region where the giant planets now reside. Some were thrown out beyond the orbit of Neptune, while others stayed put in the form of Trojan asteroids (which orbit in the same trajectory as Jupiter and other planets). This is called the Nice model.

However, not all Kuiper belt objects (KBOs) play nicely with the Nice model.

(I should point out that the model is named named for the city in France and therefore pronounced “neese”.) A new study of large scale surveys of KBOs revealed that those with nearly circular orbits lying roughly in the same plane as the orbits of the major planets don’t fit the Nice model, while those with irregular orbits do. It’s a puzzling anomaly, one with no immediate resolution, but it hints that we need to refine our Solar System formation models.

This new study is described in a recently released paper by Wesley Fraser, Mike Brown, Alessandro Morbidelli, Alex Parker, and Konstantin Baygin (to be published in the Astrophysical Journal, available online). These researchers combined data from seven different surveys of KBOs to determine roughly how many of each size of object are in the Solar System, which in turn is a good gauge of the environment in which they formed.

The difference between this and previous studies is the use of absolute magnitudes — a measure of how bright an object really is — as opposed to their apparent magnitudes, which are simply how bright an object appears. The two types of magnitude are related by the distance an object is from Earth, so the observational challenge comes down to accurate distance measurements. Absolute magnitude is also related to the size of an KBO and its albedo (how much light it reflects), both important physical quantities for understanding formation and composition.

Finding the absolute magnitudes for KBOs is more challenging than apparent magnitudes for obvious reasons: these are small objects, often not resolved as anything other than points of light in a telescope. That means requires measuring the distance to each KBO as accurately as possible. As the authors of the study point out, even small errors in distance measurements can have a large effect on the estimated absolute magnitude.

The bodies in the Kuiper Belt. Credit: Don Dixon

In terms of orbits, KBOs fall into two categories: “hot” and “cold”, confusing terms having nothing to do with temperature. The “cold” KBOs are those with nearly circular orbits (low eccentricity, in mathematical terms) and low inclinations, meaning their trajectories lie nearly in the ecliptic plane, where the eight canonical planets also orbit. In other words, these objects have nearly planet-like orbits. The “hot” KBOs have elongated orbits and higher inclinations, behavior more akin to comets.

The authors of the new study found that the hot KBOs have the same distribution of sizes as the Trojan asteroids, meaning there are the same relative number of small, medium, and large KBOs and similarly sized Trojans. That hints at a probable common origin in the early days of the Solar System. This is in line with the Nice model, which predicts that, as they migrated into their current orbits, the giant planets kicked many planetesimals out beyond Neptune.

However, the cold KBOs don’t match that pattern at all: there are fewer large KBOs relative to smaller objects. To make matters more strange, both hot and cold seem to follow the same pattern for the smaller bodies, only deviating at larger masses, which is at odds with expectations if the cold KBOs formed where they orbit today.

To put it another way, the Nice model as it stands could explain the hot KBOs and Trojans, but not the cold. That doesn’t mean all is lost, of course. The Nice model seems to do very well except for a few nagging problems, so it’s unlikely that it’s completely wrong. As we’ve learned from studying exoplanet systems, planet formation models are a work in progress — and astronomers are an ingenious lot.

January 16, 2014December 23, 2015 by Matthew Francis

New Online Classes to Help You Learn More about the Universe

Dark matter in the Bullet Cluster. Otherwise invisible to telescopic views, the dark matter was mapped by observations of gravitational lensing of background galaxies. Credit: X-ray: NASA/CXC/CfA/ M.Markevitch et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/ D.Clowe et al. Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.;

Roughly eighty percent of all the mass in the Universe is made of dark matter – a mysterious invisible substance responsible for the structure of galaxies and the patterns of the cosmos on the very largest scales. But how do we know that?

Astronomical images are beautiful, but that’s not their primary purpose from a scientist’s point of view. How can we take those images and infer things about what they are?

We only know of one planet harboring life: Earth. But that doesn’t mean we don’t know anything about the possibility of life elsewhere in the cosmos. How can we infer things about possible alien organisms when we can’t see them (yet)?

If you’re curious about those and other classes, CosmoAcademy — a project from the CosmoQuest educational and citizen-science group — could be for you. We’re offering three new online classes: Introduction to Dark Matter, Introduction to Astronomy via Color Imaging, and Life Beyond Earth: Introduction to Astrobiology.

These classes are short, four-hour courses designed for curious but busy people. All CosmoAcademy classes are offered online through Google+ Hangouts, a type of video chat. Part of the reason we do that is to limit the size of courses to eight students. That allows us to provide individual instruction in a way no other kind of online class is able to do – you aren’t a faceless student, but part of every discussion. In fact, if there’s a topic you want to discuss, there’s a good chance your instructor will take the time to talk about it.

Interested? See our course listings, and please let me know if you have any questions. Here are a few more details:

CQX015: Introduction to Dark Matter

Roughly eighty percent of all the mass in the Universe is made of dark matter – a mysterious invisible substance responsible for the structure of galaxies. But how do we know that? In this course, we’ll examine the evidence in favor of dark matter’s existence, from the rotation of galaxies to the radiation left over from the infancy of the cosmos. After that, we’ll examine what we can infer about the identity of dark matter and sketch out some of the experiments designed to detect it. This class assumes no background except a strong interest in astronomy and cosmology.

Instructor: Matthew Francis
Course structure: Two weeks, four 60-minute meetings
Meeting times: Tuesdays and Thursdays, 9–10 PM US Eastern time (6-7 PM US Pacific time)
Course dates: January 28—February 6, 2014

Enroll today!

CQX021: Introduction to Astronomy Via Color Imaging

When astronomers look at a star, nebula or galaxy for the first time, they see some unreachably distant object acting in some unknown way. What does it have to be made of and how does it have to be acting to look like that? In this class we will be looking at how we use the visual appearance of astronomical objects to figure out what they are. We will examine this problem by making our own color images from the sources provided by observatories from real research projects. From the subtle hues of stars in a distant galaxy to the eerie neon colors of nebulae to the chaotic Sun, by looking at objects in the right light, we can find out what makes them tick.

Instructor: Peter Dove
Course structure: Two weeks, four 60-minute meetings
Meeting times: Tuesdays and Thursdays, 8–9 PM US Eastern time (5-6 PM US Pacific time)
Course dates: Tuesday, February 25—Thursday, March 6

Enroll today!

CQX013 – Astrobiology: Life in the Universe

What will it take to find extraterrestrial life? Frank Drake penned his famous “equation” to determine the instances of life in the Galaxy over 50 years ago. Meant more as a discussion guideline than a rigorous mathematical formula, it will guide our discussion on the science of astronomy, biology, and astrobiology as we consider the possibility of life in the Universe.

Instructor: Nicole Gugliucci
Course structure: Two weeks, four 60-minute meetings
Meeting times: Mondays and Thursdays, 9–10 PM US Eastern time (6-7 PM US Pacific time)
Course dates: Monday, March 17 — Thursday, March 27

Enroll today!

January 16, 2014December 23, 2015 by David Dickinson

A “MiniMoon” Seen Around the World

A 99% illuminated Moon within 24 hours of Full. Image Credit: Stephen Rahn.

So, did last night’s Full Wolf Moon seem a bit tinier than usual? It was no illusion, as avid readers of Universe Today know. As we wrote earlier this week, last night’s Full Moon was the most distant for 2014, occurring just a little under three hours after apogee.

The Full Moon, a "Moon Dog" halo, and a rare parhelic (or do you say Palunic?) arc as seen from North Slope Borough County, Alaska. Credit-Jason Ahrns. — The Full Moon, a “Moon Dog” halo, and a rare parhelic (or do you say Palunic?) arc as seen from North Slope Borough County, Alaska. Credit-Jason Ahrns.

Sure, the Moon reaches apogee every lunation, at a distance nearly as far. In fact, the Moon at apogee can be as far as 406,700 kilometres distant, and last night’s apogee, at 406,536 kilometres, is only the second farthest for 2014. The most distant apogee for 2014 falls on July 28^th at 3:28 Universal Time (UT) at just 32 kilometres farther away from our fair planet at 406,568 kilometres distant.

A 20 image composite shot using a Canon 60Da camera and a a 10" Newtonian telescope. Credit-Stephen Rahn. — A 20 image composite shot using a Canon 60Da camera and a a 10″ Newtonian telescope. Credit-Stephen Rahn.

What made last night’s MiniMoon special was its close proximity in time to the instant of Full phase. The July 2014 apogee, for example, will occur just a day and four hours from New phase.

The 2014 MiniMoon rising behind clouds from Hudson, Florida. Photo by author.

Of course, it isn’t the Moon that’s doing the shrinking, though you’d be surprised the stuff we’ve seen around ye ole Web even on reputable news sites over the past week. The variation of the apparent size of the Full Moon does make for an interesting study in perception. The Moon varies in size from apogee to perigee from about 29.3’ across to 34.1’. This is variation amounts to 14% in apparent diameter.

The Full MiniMoon, clouds, and Jupiter. Credit- Shaun Reynolds, Bungay UK. — The Full MiniMoon, clouds, and Jupiter. Credit– Shaun Reynolds (@shaunreylec), Bungay UK.

Here’s an interesting challenge that you can do for a one year period, requiring just a working set of eyes: observe the Full Moon for 12 successive lunations. Can you judge which one was the “SuperMoon” and which one was the “MiniMoon” without prior knowledge?

A "MiniMoon Nebula..." The Full Moon illuminating foreground clouds. The HDR visualization of the Moon was added for context. Taken with a tripod mounted Nikon P90 Bridge camera. Credit: Giuseppe Petricca of Sulmona, Abruzzo, Italy. — A “MiniMoon Nebula…” The Full Moon illuminating foreground clouds. The HDR visualization of the Moon was added for context. Taken with a tripod mounted Nikon P90 Bridge camera. Credit: Giuseppe Petricca of Sulmona, Abruzzo, Italy.

And as you can see, we also got plenty of pictures here at Universe Today from readers of the Mini-Moon from worldwide.

The MiniMoon shot using a mobile phone held up to the eyepeice of a telescope. Credit-Andrew Millarkie (@Millarkie) — The MiniMoon shot using a mobile phone held up to the eyepiece of a telescope. Credit-Andrew Millarkie (@Millarkie) Glasgow, Scotland.

The rare occurrence of an “Extreme-MiniMoon” — or do you say “Ultra?” — also sparked a lively discussion about the motion of the Moon, how rare this event is, and when it was last and will next be surpassed. A fun online tool to play with is Fourmilab’s Lunar Apogee and Perigee Calculator. Keep in mind, the motion of the Moon is complex, and accuracy for most planetarium programs tends to subside a bit as you look back or forward in time. The distances used in Fourmilab’s calculations are also geocentric, accounting for the center-to-center distance of the Earth-Moon system.

The MiniMoon versus streetlights as seen from Nueva Casarapa, Venezulua. Credit: Jose Mauricio Rozada (@jmrozada) — The MiniMoon versus streetlights as seen from Nueva Casarapa, Venezuela. Credit: Jose Mauricio Rozada (@jmrozada)

Suffice to say, this year’s Full MiniMoon was the most distant for several decades before 2014 or after.

Anthony Cook of the Griffith Observatory notes that JPL’s Horizons web interface gives a max distance for the Moon of 406,533 kilometres at 1:35 UT earlier today, 3 hours and 19 minutes prior to Full.

The Full MiniMoon glimpsed between clouds as seen from central Illinois. Credit-Matt Comerford, (@kb9uwu)

The next closest spread of apogee versus perigee occurs on November 18^th, 1994 at 1 hour and 51 minutes apart, and 2014’s Mini-Moon won’t be surpassed in this regard until May 13^th, 2052. Looking at the distances for the Moon on these dates using Starry Night, however, we get an slightly closer occurrence of 406,345 kilometres for 1994 and 406,246 kilometres for 2052.

The Full MiniMoon rising behind a stand of trees. Credit- Sculptor Lil. — The Full MiniMoon rising behind a stand of trees. Credit– Sculptor Lil.

And to top it off, the 1994 Mini-Moon was during a partial penumbral eclipse as well… we’ll leave that as a homework assignment for the astute readers of Universe Today to calculate how often THAT occurs. It should be fairly frequent over the span of a century, as the Moon has to be at Full phase for a total lunar eclipse to occur.

The MiniMoon as captured by Manish Agarwal from Rajasthan, India. — The MiniMoon as captured by Manish Agarwal (@iManishAgarwal) from Rajasthan, India.

Looking over a larger span of time, @blobrana notes on Twitter that closer occurrences of apogee versus Full Moon with the same approximate circumstances as 2014 also occurred on October 29^th 817 AD (with a 1 hour and 38 minute difference) and won’t occur again until December 20^th, 2154. If research can prove or disprove that these events were even more distant, then the 2014 Extreme MiniMoon was a millennial rarity indeed…

Perhaps this won’t be the last we’ve heard on the subject!

January 16, 2014April 26, 2016 by Bob King

John Dobson, Inventor of the Popular Dobsonian Telescope, Dead at 98

John Dobson, amateur astronomer and astronomy popularizer, died Jan. 14 at 98 in Burbank, Calif. Credit: Wikipedia

The cosmos lost a good soul Wednesday. John Dobson, famous as the creator of the simple, low-cost Dobsonian telescope, passed away on Jan. 15, 2014. His obituary appeared on the website of the Sidewalk Astronomers:

“It is with heavy hearts that we must report the passing of John Dobson. He died peacefully this morning, Wednesday, January 15th, in Burbank, California. He was 98 years old. He leaves behind a son, numerous close friends, and fans and admirers worldwide.

On March 8th, in honor of John, this year’s ISAN (International Sidewalk Astronomy Night) will be dedicated to his memory. Amateur astronomers around the globe can join in and celebrate John’s life and continue to carry the torch that he lit back in 1968 when he co-founded the San Francisco Sidewalk Astronomers.”

John Dobson tugs on his ear during a lecture as guest speaker during Northwoods Starfest near Eau Claire, Wis. U.S. in August 2000. Credit: Bob King — John Dobson tugs on his ear to make a point during a lecture as guest speaker during Northwoods Starfest near Eau Claire, Wis. U.S. in August 2000. Credit: Bob King

Dobson was born in Beijing, China but moved with his parents to San Francisco in 1927. After spending 23 years in a monastery, some of which time was spent sneaking out to build telescopes and observe the night sky, he left to co-found the San Francisco Sidewalk Astronomers in 1968, a group dedicated to showing people on the street the wonders of the night sky using large (for the time) telescopes.

Dobson’s interest in astronomy started in the early 1950s when he built a small telescope using spare parts found in a junk store. He wanted to see for himself what the universe looked like. By 1956, John got a hold of a 12-inch slab of porthole glass and ground it into a mirror following instructions from Allyn J. Thompson’s classic book Making Your Own Telescope. His first look at the last quarter turned him into an astro-evangelist:

“It looks like you’re coming in for a landing,” he wrote in his own telescope making book many years later. From that moment on Dobson felt “that everybody who lives in this world has to see that.”

The writer with his 10-inch Dobsonian reflecting telescope. The scope comes in two pieces like John Dobson's original design - a cardboard tube with the optics that sits in a cradle. See photo below to see how a "Dob" works. Credit: Bob King — The writer with his 10-inch Dobsonian reflecting telescope. The scope breaks down into two pieces like John Dobson’s original design – a cardboard tube with the optics and a cradle. See photo below to see how a “Dob” works. Credit: Bob King

Toting beat-up, monster telescopes everywhere from downtown San Francisco and to national parks across the country, Dobson made good on his promise. He lectured widely on astronomy and cosmology, rejecting the Big Bang Theory for his own Recycling Steady State Theory.

Agree or not with his cosmology, Dobson shook up the amateur telescope making universe with an innovative telescope design based on simplicity. Most telescopes of his day were small refracting telescopes or small to modest-sized reflectors with metal tubes and heavy equatorial mounts. Neither was exactly user-friendly nor offered much light gathering ability.

The mount is a simple altitude-azimuth or "alt-az" design. The scope moves up and down (altitude) against teflon pegs (right) and turns through in a circle (azimuth) on teflon pads against a laminate surface on the base. Credit: Bob King — The mount is a simple altitude-azimuth or “alt-az” design. The scope moves up and down (altitude) against teflon pegs (right) and turns through in a circle (azimuth) on teflon pads against a laminate surface on the base. Credit: Bob King

John used simple materials like porthole glass, cardboard tubes and wooden altitude-azimuth (alt-az) mounts to build incredibly easy to use large telescopes. However primitive, his instruments delivered bright and satisfying images of all the cool, faint stuff in the sky to the average Joe and Jane. Each telescopes had its own name: Little Bertha, Delphinium, Stellatrope, Little One (an 18-incher).While alt-az mounts were nothing new, Dobson combined cheap materials, large mirrors and a simpler approach to mountings that made his telescope style unique. Too unique for some.

Get to know John Dobson a little better in this video titled “Have Telescopes, Will Travel”

In the summer of 1969 Dobson pitched his simple ideas to Sky and Telescope magazine. Then-editor Charles Federer wrote back a polite rejection, stating that Dobson’s techniques weren’t up to standards and “could hardly lead to satisfactory instruments in the kind most amateurs want in these large sizes.”

How wrong this early assessment would turn out to be! His ideas became widely adopted starting in the early 1980s, when Coulter Optical began manufacturing 13.1-inch and 17.5-inch large reflecting telescopes with inexpensive mirrors and simple alt-azimuth mounts that soon were called “Dobsonian” because they were based on John’s original designs.

John Dobson's book on how to build your own telescope featured a unique cover made of plywood, a favorite material for building Dobsonian mounts. Credit: Bob King — John Dobson’s book on how to build your own telescope featured a unique cover made of plywood, a favorite material for building Dobsonian mounts. Credit: Bob King

These days, Dobsonian reflecting telescopes have gone viral. There are how-to books on how to build everything from simple to sophisticated Dobsonsians , including Dobson’s own unique plywood-bound How and Why to Make a User-Friendly Sidewalk Telescope. Don’t want to build one yourself? Most telescope outlets sell several lines of Dobsonians. Heck, my 10-inch and 15-inch reflectors, the most used of my instruments, originate from John’s genius.

When someone asks me to recommend a telescope, I always say “Get a Dobsonian!” They’re extremely portable, very stable, quick to set up and take down and the least expensive per inch of aperture of any scope out there.

John Dobson's signature in his book on telescope making. Credit: Bob King — John Dobson’s signature in his book on telescope making. Click image for more on Dobson’s life and writings. Credit: Bob King

Dobson wanted everyone to share in the universe’s bounty, the better to appreciate our lives and our world. The next clear night tilt your head back, gaze up at the stars and imagine John up there smiling. What an incredible view he must have.

January 15, 2014December 23, 2015 by David Dickinson

An Amazing Capture of Jupiter and its Moons

Astrophotographer Michael Phillips with the gear used to capture the Jupiter rotation animation. Credit-Michael Phillips

It’s always a thrill to watch the action at Jupiter, as its moons pass in front of and behind the gas giant planet. We wrote recently about this month’s opposition of Jove on January 5^th, marking the start of the Jupiter evening viewing season for 2014.

Astrophotographer Michael A. Philips also recently undertook a challenging series of sequences of Jupiter and its moons Io and Ganymede, with stunning results. You can see the motion of Jupiter’s rotation, the Great Red Spot and even a bit of cloud swirl as Io disappears behind Jupiter and Ganymede begins to transit in front and cast a shadow back onto the Jovian cloud tops.

Concerning the capture, Michael wrote on his blog:

“This night was a lucky night. I had not looked at the weather forecast enough to know if it would be good or not. Cold temps aside, I decided earlier in the day to set up and go out with the 14” f/4.5 scope named Akule. As an added bonus, Mitchell Duke tipped me off to a transit of the Jovian moon, Ganymede.”

Note that Jupiter and its moons are currently casting their shadows nearly straight back from our perspective. Expect that to change, however, in the coming months,as Jupiter heads towards eastern dusk quadrature on April 1st and we see the action from a sideways angle. Watch the video in full screen mode and you’ll note that Mike captured some detail on the surface of Ganymede as well! Generally, at the eyepiece, the moons of Jupiter disappear entirely due to low contrast against the bulk of the planet, with only the black dot of the shadow seen… this video capture gives the ingress of Ganymede at the start of the transit a great 3-D appearance.

Webcam imaging of planets has really taken off in the past decade, with backyard astronomers now routinely capturing images that far surpass professional and textbook images from just a decade prior. Great images can be taken using nothing more than a telescope, a laptop, free image stacking software such as Registax, and a webcam converted to fit into an eyepiece holder… you may find that you’ve got the gear sitting around to image Jupiter, tonight.

Mr. Phillips rig, however, is a little more advanced. He notes in the description of the video that he’s using a Flea3 camera from PointGrey Research with a 5x Barlow lens yielding a 9200mm focal length. He’s also shooting at 120 frames per second, and taking successive red, green and blue images for 30 seconds. Finally, a derotation of Jupiter – yes, it really rotates that quickly, even in a short sequence – is accomplished using a sophisticated program named WINJupos.

Video stacking gives processors the ability to “freeze” and nab the best moments of seeing from thousands of frames. Some imagers hand select frames one by one, though many programs, such as Registax, use algorithms to nab the best frames from a preselected percentage of the total shot.

Local seeing conditions also play a key role in image capturing.

“I moved far away from the house as possible, and I think that helped some,” Michael noted. “I also started cooling the spit out of the mirror, aggressively. Even when cooled for a few hours in the winter, the heat in the Pyrex mirror comes back. I think there’s a small heat engine inside the beast!”

For best results, imagers tend to go after planets when they’re at their highest in the sky, and viewed through the least amount of turbulent atmosphere. This is when a planet is transiting the local north to south meridian, and when it’s at opposition, which Jupiter is this month. At opposition, a planet transits at local midnight. The same goes for the best opportunities for visual observing as well.

Shadow transits of Jupiter’s moons are also just plain fun to watch. In an often unchanging universe, they offer a chance to see something unfolding in real time. Jupiter has the fastest rotation of any planet at 9.9 hours, and the large Galilean moons of Io, Europa, Ganymede and Callisto are tidally locked in their rotation, keeping one hemisphere permanently turned towards Jupiter like the Moon does orbiting the Earth. The inner three moons also keep a 1:2:4 orbital resonance, assuring you’ll never see more than three of the four Galilean moons transiting from your line of sight at once. You can see two of the inner three moons, plus Callisto in transit, but never all four at the same time! A triple transit last occurred on October 12^th, 2013, and will next occur for observers in eastern Europe and Africa this year on June 3^rd.

We’re also currently in the midst of a series of shadow transits for the outermost Galilean moon Callisto, which end in July 2016. Can you identify the different moons by the size and hue of shadows they cast? Sky & Telescope publishes a great table for the ingress and egress of Jupiter’s moons. You can also check them out using the freeware program Stellarium.

The double shadow transit of February 6th as seen at 11:22 UT. Created by the author using Starry Night Education software.

Can’t wait that long? A double shadow transit involving Europa and Callisto occurs in just a few weeks for western North America from 10:20 UT-12:44UT on the morning of February 6^th, a chance for another stunning animation sequence…

Congrats to Michael Phillips on a great capture!

January 14, 2014December 23, 2015 by David Dickinson

A Possible Meteor Shower from Comet ISON?

Hey, remember Comet C/2012 S1 ISON? Who can forget the roller-coaster ride that the touted “Comet of the Century” took us on last year. Well, ISON could have one more trick up its cosmic sleeve –although it’s a big maybe — in the form of a meteor shower or (more likely) a brief uptick in meteor activity this week.

In case you skipped 2012 and 2013, or you’re a time traveler who missed their temporal mark, we’ll fill you in on the story thus far.

Comet ISON was discovered by Artyom Novichonok and Vitali Nevski on September 21^st, 2012 as part of the ongoing International Scientific Optical Network (ISON) survey. Shortly after its discovery, researchers knew they had spotted something special: a sungrazing comet already active at over 6.4 Astronomical Units (A.U.s) from the Sun. The Internet then did what it does best, and promptly ran with the story. There were no shortage of Comet ISON conspiracy theories for science writers to combat in 2013. It’s still amusing to this day to see predictions for comet ISON post-perihelion echo through calendars, almanacs and magazines compiled and sent to press before its demise.

ISON back in the day. Credit-Efrain Morales Rivera, Jaicoa Observatory Aguadilla, Puerto Rico

The frenzy for all things ISON reached a crescendo on U.S. Thanksgiving Day November 28^th 2013, as ISON passed just 1.1 million kilometres from the surface of the Sun. Unfortunately, what emerged was a sputtering ember of the comet formerly known as ISON, which faded from view just as it was slated to reenter the dawn sky.

Hey, we were crestfallen as well… we had our semi-secret dark sky site pre-selected for ISON imaging post-perihelion and everything. Despite heroic searches by ground and space-based assets, we’ve yet to see any compelling recoveries of Comet ISON post-perihelion.

This week, however, Comet ISON may put on its last hurrah, in the form of a minor meteor shower. We have to say from the outset that we’re highly skeptical that an “ISON-id meteor outburst” will grace the skies. Known annual showers are fickle enough, and it’s nearly impossible to predict just what might happen during a meteor shower with no past track record.

But you won’t see anything if you don’t try. If anything is set to occur, the night of January 15^th into the 16^th might just be the time to watch. This is because the Earth will cross the orbital plane of ISON’s path right around 9:00 PM EST/2:00 UT. Last year, ISON passed within 3.3 million kilometres of the Earth’s orbit on its inbound leg. Earlier last year, ISON was estimated to have been generating a prodigious amount of dust, at a rate of about 51,000 kilograms per minute. Any would-be fragments of ISON outbound would’ve passed closest to the Earth at 64 million kilometres distant on the day after Christmas last year. Veteran sky observer Bob King wrote about the prospects for catching ISON one last time during this month back in December 2013.

A simulation showing Earth crossing the plane of Comet ISON’s orbit early on January 16th. Credit: NASA/JPL Solar System Dynamics Small Body Database Browser.

Another idea out there that is even more unlikely is the proposal that dust from Comet ISON may generate an uptick in noctilucent cloud activity. And already, a brief search of the internet sees local news reports attempting to tie every meteor observed to ISON this week, though no conclusive link to any observed fireball has been made.

The radiant to watch for any possible “ISON-ids” sits near the +3.5 magnitude star Eta Leonis in the sickle of Leo. Robert Lundsford of the American Meteor Society notes in a recent posting that any ISON-related meteors would pass through our atmosphere at a moderate 51 kilometres a second, with a visible duration of less than one second.

Note that meteor activity has another strike against it, as the Moon reaches Full on the same night. In fact, the Full Moon of Wednesday January 15^th sits in the constellation Gemini,just 32 degrees away from the suspect radiant!

Another caveat is in order for any remaining dooms-dayers: no substantial fragments of ISON are (or ever were) inbound and headed towards our fair planet. Yes, we’re seeing rumblings to this effect in the pseudoscience netherworlds of ye ole Internet, along with ideas that ISON secretly survived, NASA “hid” ISON, ISON cloaked like a Romulan Bird of Prey, you name it. Just dust grains, folks… a good show perhaps, but nothing more.

As near as we can tell, talk of a possible meteor shower generated from Comet ISON goes all the way back to a NASA Science News article online from April 2013. Radio observers of meteor showers should be alert for a possible surge in activity this week as well, and it may be the case that more radio “pings” will be noted than visual activity what with the light-polluting Full Moon in the sky. The radiant for any would-be “ISON-ids” transits highest in the sky for northern hemisphere observers at around 2 AM local.

But despite what it has going against it, we’d be thrilled if ISON put on one last show anyhow. It’s always worth watching for meteor activity and noting the magnitude and from whence the meteor came to perhaps note the pedigree as to the shower it might belong to.

The next annual dependable meteor shower won’t be until the night of April 21^st to the 22^nd, when the Spring Lyrids are once again active. And this year may just offer a special treat on May 24^th, when researchers have predicted that the Earth may encounter debris streams laid down by Comet 209P LINEAR way back in 1803 and 1924… Camelopardalids, anyone? Now, that’s an exotic name for a meteor shower that we’d love to see trending!

-Catch sight of any “ISON-ids?” we’d love to see ‘em… be sure to post said pics at Universe Today’s Flickr pool.

January 13, 2014December 23, 2015 by Brian Koberlein

Why Einstein Will Never Be Wrong

Einstein Lecturing — Albert Einstein during a lecture in Vienna in 1921. Credit: National Library of Austria/F Schmutzer/Public Domain

One of the benefits of being an astrophysicist is your weekly email from someone who claims to have “proven Einstein wrong”. These either contain no mathematical equations and use phrases such as “it is obvious that..”, or they are page after page of complex equations with dozens of scientific terms used in non-traditional ways. They all get deleted pretty quickly, not because astrophysicists are too indoctrinated in established theories, but because none of them acknowledge how theories get replaced.

For example, in the late 1700s there was a theory of heat known as caloric. The basic idea of caloric was that it was a fluid that existed within materials. This fluid was self-repellant, meaning it would try to spread out as evenly as possible. We couldn’t observe this fluid directly, but the more caloric a material has the greater its temperature.

Ice-calorimeter from Antoine Lavoisier’s 1789 Elements of Chemistry. (Public Domain)

From this theory you get several predictions that actually work. Since you can’t create or destroy caloric, heat (energy) is conserved. If you put a cold object next to a hot object, the caloric in the hot object will spread out to the cold object until they reach the same temperature. When air expands, the caloric is spread out more thinly, thus the temperature drops. When air is compressed there is more caloric per volume, and the temperature rises.

We now know there is no “heat fluid” known as caloric. Heat is a property of the motion (kinetic energy) of atoms or molecules in a material. So in physics we’ve dropped the caloric model in terms of kinetic theory. You could say we now know that the caloric model is completely wrong.

Except it isn’t. At least no more wrong than it ever was.

The basic assumption of a “heat fluid” doesn’t match reality, but the model makes predictions that are correct. In fact the caloric model works as well today as it did in the late 1700s. We don’t use it anymore because we have newer models that work better. Kinetic theory makes all the predictions caloric does and more. Kinetic theory even explains how the thermal energy of a material can be approximated as a fluid.

This is a key aspect of scientific theories. If you want to replace a robust scientific theory with a new one, the new theory must be able to do more than the old one. When you replace the old theory you now understand the limits of that theory and how to move beyond it.

In some cases even when an old theory is supplanted we continue to use it. Such an example can be seen in Newton’s law of gravity. When Newton proposed his theory of universal gravity in the 1600s, he described gravity as a force of attraction between all masses. This allowed for the correct prediction of the motion of the planets, the discovery of Neptune, the basic relation between a star’s mass and its temperature, and on and on. Newtonian gravity was and is a robust scientific theory.

Then in the early 1900s Einstein proposed a different model known as general relativity. The basic premise of this theory is that gravity is due to the curvature of space and time by masses. Even though Einstein’s gravity model is radically different from Newton’s, the mathematics of the theory shows that Newton’s equations are approximate solutions to Einstein’s equations. Everything Newton’s gravity predicts, Einstein’s does as well. But Einstein also allows us to correctly model black holes, the big bang, the precession of Mercury’s orbit, time dilation, and more, all of which have been experimentally validated.

So Einstein trumps Newton. But Einstein’s theory is much more difficult to work with than Newton’s, so often we just use Newton’s equations to calculate things. For example, the motion of satellites, or exoplanets. If we don’t need the precision of Einstein’s theory, we simply use Newton to get an answer that is “good enough.” We may have proven Newton’s theory “wrong”, but the theory is still as useful and accurate as it ever was.

Unfortunately, many budding Einsteins don’t understand this.

Binary waves from black holes. Image Credit: K. Thorne (Caltech) , T. Carnahan (NASA GSFC)

To begin with, Einstein’s gravity will never be proven wrong by a theory. It will be proven wrong by experimental evidence showing that the predictions of general relativity don’t work. Einstein’s theory didn’t supplant Newton’s until we had experimental evidence that agreed with Einstein and didn’t agree with Newton. So unless you have experimental evidence that clearly contradicts general relativity, claims of “disproving Einstein” will fall on deaf ears.

The other way to trump Einstein would be to develop a theory that clearly shows how Einstein’s theory is an approximation of your new theory, or how the experimental tests general relativity has passed are also passed by your theory. Ideally, your new theory will also make new predictions that can be tested in a reasonable way. If you can do that, and can present your ideas clearly, you will be listened to. String theory and entropic gravity are examples of models that try to do just that.

But even if someone succeeds in creating a theory better than Einstein’s (and someone almost certainly will), Einstein’s theory will still be as valid as it ever was. Einstein won’t have been proven wrong, we’ll simply understand the limits of his theory.

January 13, 2014December 23, 2015 by David Dickinson

See the Smallest Full Moon of 2014: It’s the “Return of the Mini-Moon”

Last month's rising "Mini-Moon" of 2013. (Photo by Author)

Last month, (and last year) we wrote about the visually smallest Full Moon of 2013. Now, in a followup act, our natural satellite gives us an even more dramatic lesson in celestial mechanics with an encore performance just one lunation later with the smallest Full Moon of 2014.

We’ve noted the advent of the yearly Mini-Moon, a bizzaro twin to the often over-hyped “SuperMoon,” or Proxigean Full Moon. Occurring approximately six months apart, you can always expect lunar apogee to roughly coincide with the instant of a Full Moon about half a year after it coincides with perigee. In fact, the familiar synodic period that it takes the Moon to return to like phase (such as Full back to Full) of 29.5 days has a lesser known relative known as the anomalistic month, which is the period of time it takes the Moon to return to perigee at 27.55 days.

But the circumstances for “Mini-Moon 2014” are exceptional. The first Full Moon of the year occurs on the night of January 15^th at 11:52 PM EST/4:52 Universal Time (on January 16^th). This is just 2 hours and 59 minutes after the Moon reaches apogee at 406,536 kilometres distant at 8:53 PM EST/1:53 UT. This isn’t the farthest apogee that occurs in 2014, but it’s close: the Moon is just 32 kilometres more distant on July 28^th, 2014. Apogee can vary from 404,000 to 406,700 kilometres, and this month’s apogee falls just 164 kilometres short of the maximum value.

As you can see, this year’s Mini-Moon falls extremely close to apogee… in fact, you have to go all the way back to the Full Moon of November 18^th, 1994 to find a closer occurrence, and this year’s won’t be topped until May 13^th, 2052! The Moon will appear only 29’ 23” in size on Wednesday night at moonrise, very close to its minimum possible value of 29’ 18”. This is also almost 5 arc minutes smaller than the largest “Super-Moon” possible.

Cool factoid: you actually move closer to the Moon as it rises, until it transits your local meridian and you begin moving away from it, all due to the Earth’s rotation. You can thus gain and lose a maximum of one Earth radii distance from the Moon in the span one night.

We also just passed the most northern Moon of 2014, as it reached a declination of 19 degrees 24’ north this morning at 8:00 UT/3:00 AM EST. This is a far cry from the maximum that can occur, at just over 28 degrees north. This is because we’re headed towards a “shallow year” as the Moon’s motion bottoms out relative to the ecliptic in 2015 and once again begins to widen out in its 18+ year cycle to its maximum in 2024-25.

The position of the Moon Monday night on January 13th in Orion. Credit: Stellarium

This week’s Moon also visits some interesting celestial targets as well. The waxing gibbous Moon sits just 5.1 degrees south of the open cluster M35 tonight. Notice something odd about the Moon’s position Monday night? That’s because it is passing through Orion the Hunter, one of the six non-zodiacal constellations that it can be found in. Can you name the other five? Hint: one was the “13^th sign of the zodiac that created a non-traversy a few years back.

On Tuesday evening, the Moon passes six degrees from the planet Jupiter. This presents a fine time to try and spot the planet in the daytime to the Moon’s upper left, just a few hours prior to sunset.

The Moon will also occult the +3.6 magnitude star Lambda Geminorum on January 15^th for observers in northwestern North America. In fact, viewers along a line crossing central British Columbia will witness a spectacular graze along the lunar limb as the star winks out behind lunar mountains and pops into view as it shines through lunar valleys along the edge of the Moon. This can make for an amazing video capture, we’re just throwing that out there…

The occultation footprint for Lambda Geminorum for January 15th. (Created using Occult 4.01 software) — The occultation footprint for Lambda Geminorum for January 15th. (Created using Occult 4.10.11 software)

In addition to being this year’s Mini-Moon, the January Full Moon is also known as the Wolf Moon in the tradition of the Algonquin Native Americans, as January was a time of the mid-winter season when starving wolf packs would howl through the long cold night. The January Full Moon is also sometimes referred to as “The Moon after Yule,” marking the first Full Moon after Christmas.

And just when is the next Super Moon, you might ask? Well, 2014 has three Full Moons occurring within 24 hours of perigee starting on July 15^th and finishing up on September 8^th. But the most notable is on August 10^th, when the Moon passes perigee just 27 minutes from Full. Expect it to be preceded by the usual lunacy that surrounds each annual “Super Moon” as we once again bravely battle the forces of woo and describe just exactly what a perigee Full Moon isn’t capable of. Yes, we still prefer the quixotic term “Proxigean Moon,” but there you go.

Also, be sure to wave a China’s Chang’e-3 lander and rover in the Bay of Rainbows (Sinus Iridum) as you check out this week’s Full Moon, as it just experienced its first lunar sunrise this past week.

Be sure to send those Mini-Moon pics and more in to Universe Today, and let’s get this week’s #MiniMoon trending on Twitter!

January 13, 2014December 23, 2015 by Bob King

LEDs: Light Pollution Solution or Night Sky Nemesis?

New LED lighting along Michigan Street in downtown Duluth, Minn. has brightened and whitened up the area considerably compared to the days of high-pressure sodium lighting. Credit: Bob King

You may have noticed a change underway in your city lighting. High pressure sodium lights, with their familiar orange glow, are quickly being replaced by new, energy efficient blue-white LED (light emitting diode) lighting. Is this the beginning of a new assault on the night or an opportunity to use light more wisely? Many of us first became aware of LEDs in amplifiers, computers and the flashlights we use for seeing our star charts at night. More recently, LEDs became a big hit with Christmas lighting. And why not? Although they cost considerably more, the bulbs last much longer, use a fraction of the energy compared to incandescent and sodium lighting and don’t contain materials like mercury – common in fluorescent lighting – that can harm the environment. A typical incandescent bulb lasts about 750 hours while an LED bulb can glow for up to 50,000 hours. What’s not to like?

Small individually colored LED lights. LEDs are an electronic light based on semiconductors instead of — Small individually colored LED lights. LEDs light up when an electric current excites electrons inside a semidconductor to produce photons of light. Click to learn more. Credit: Piccolo Namek

The changeover to LED street lighting is already underway in my own city of Duluth, Minn. U.S. I noticed this one night this fall while driving home from work. Buildings and intersections that had been orange the night before were bathed in a far more intense blue-white light. Don’t get me wrong. Our city engineers deserve high marks for adhering to good lighting standards by packaging the new lights in shielded housings with minimal light spill upwards and to the sides. Light in those directions not only creates unwanted glare but seriously brightens the night sky, robbing many of the joys of stargazing.

Comparison of lighting colors and intensity of the new LED streetlights (left) and the older high-pressure sodium vapor lamps.

Still, everything was not OK. The LED street lights were INTENSELY bright, much more so than the “old-fashioned” sodiums. Looking up was like staring into the sun. If you have the opportunity, step under an orange sodium street light and then under an LED. You’ll be amazed at the difference in light intensity. To gauge the approximate difference in brightness between the two, I pulled out my camera and took a light meter reading on the pavement beneath an LED lamp and then under a high-pressure sodium lamp. The LED was brighter by more than more than one camera “stop” or more than twice as bright.

You can’t complain about the color rendition – the whiter LED light is far better – but the increased intensity doesn’t bode well for stargazers.

Direct comparison of two consecutive light standards - LED in the foreground, high pressure sodium behind it. Credit: Bob King — Direct comparison of two consecutive light standards – LED in the foreground, high pressure sodium behind it. Notice that both lights are well-shielded, ie. no part of the bulb extends beyond its housing. Credit: Bob King

As long as LEDs are shielded, light spill and glare are relatively well-controlled, but light reflected from the ground also goes up into space to light the sky. Here in the northern U.S. where snow typically covers the ground from November through March, winter night skies are the most light polluted; LED street lighting will only exacerbate the situation.

Inexpensive LED wall pack lighting lights a sidewalk and produces large amounts of glare and wasted light. Credit: Bob King

In the big picture however, that’s only a minor headache. LEDs are a wonderful technology, but the benefits they provide in cost savings and long life ultimately guarantee their proliferation in ornamental, building and parking lot illumination. Much of that lighting is unshielded and heavy on glare, making driving at night more difficult, wasting energy and preserving what dark sky remains more challenging. Indeed, the transition is already underway.

Unshielded LED ornamental lighting at a new housing development. Credit: Bob King — Brilliant, unshielded LED ornamental lighting at a new housing development. The full moon is seen at top. Credit: Bob King

Like an outbreak of mushrooms, LED “wall pack” lights – the ones that shine directly outward without any shielding – have started to appear on the outside walls of buildings as a cheap solution for lighting up walkways and parking lots. They’re replacing the equally bad but half as bright sodium lamps. Ornamental LED lamps in a new housing development in town recently turned night into day. Residents complained and wrote letters to the editor. To their credit, the owners dimmed the lights, but the fixtures were poorly designed to start and still too bright for many.

Closeup of LED ornamental light fixtures. Credit: Bob King — Closeup of LED ornamental light fixtures with little shielding. Credit: Bob King

One additional issue with LED ornamental and street lighting has to do with color. Although natural color LED lighting is available, high-efficiency LED lights emit a much bluer light than sodium vapor. Blue-rich light not only increases the amount of glare sensed by the human eye but also the amount of visible light pollution. Other effects of light trespass and glare include sleeping problems and even an increased risk for certain cancers. We humans need the night more than we know.

LEDs are only part of the problem of course. The real issue is the ever-increasing amount of light pollution worldwide and the potential for new LEDs to make it worse. True, we can take advantage of the ability to adjust and dim current lighting to more suitable levels. LEDs are also highly directional, making it easy to point them just where they’re needed. Finally, new high-efficiency more natural (less blue) LEDs are now available that can help reduce light pollution.

First electric lighting: New York City around 1880.

I encourage everyone to learn all you can about the new lighting and work with you local city councils and town boards to use the light wisely, particularly in new developments, parking lots and for building illumination. There’s no question that LED lighting can be used wisely to make everyone happy – stargazers, drivers, shoppers and walkers. For help and more information, the International Dark-Sky Association (IDA) is a great place to start. Here are some additional resources:

* IDA Simple Guidelines for Lighting Regulations for Small Communities, Urban Neighborhoods and Subdivisions – Great background information on what you’ll need to know before you approach your town board
* Sample Light Ordinances
* Great examples of dark sky compliant ornamental LED light fixtures