Universe Today

February 20, 2013December 23, 2015 by Elizabeth Howell

Hollywood’s Mixed Portrayal of John Glenn

Actor Ed Harris portrayed astronaut John Glenn in The Right Stuff, a 1983 movie following the beginning of the NASA astronaut program. Credit: The Ladd Co. (screenshot)

We’ll be the first to admit that the 1983 movie The Right Stuff takes artistic license when it talks about the Mercury program and other events. It exaggerates problems between the astronauts, portrays the journalists as unthinking buffoons and misrepresents historical events such as breaking the speed of sound.

Late in the three-hour film, the movie turns to astronaut John Glenn‘s first flight in space, which took place on this day in 1962. Glenn was the first American to make an orbital flight of the Earth. He returned a national hero.

Below we’ll highlight a few points of similarity and difference between the movie and John Glenn’s own account of the flight of Friendship 7, which he detailed in his 1999 biography John Glenn: A Memoir. And yes, the rest of this post does contain spoilers for those who haven’t seen the film.

– Visit from Lyndon Johnson. During an aborted launch attempt, the movie shows Lyndon Johnson parked nearby the Glenns’ house in a limousine, ordering an aide to let him inside. Glenn’s wife Annie (through a fellow astronaut wife) keeps informing the hapless assistant that there’s no way Johnson (and the TV cameras he wants to include) can come in. While Glenn’s actual account doesn’t specify where the vice-president of the United States was at that time, he does talk about the request and refusal. “She said she was tired, she had a headache, and she just wasn’t going to allow all those people in her house … I told her whatever she wanted to do, I would back her up 100 percent.”

– Threat to remove Glenn from the flight. In The Right Stuff, Glenn then gets into a shouting argument with a NASA official nearby, who orders him to get on the phone and tell Annie to let the vice-president in. The NASA official threatens to replace Glenn with another astronaut, at which point Glenn’s colleagues surround him and the official backs down. Glenn confirms the incident, but does not mention other astronauts: “I saw red. I said that if they wanted to do that, they’d have a press conference to announce their decision and I’d have one to announce mine, and if they wanted to talk about it anymore, they’d have to wait until I took a shower. When I came back, they were gone and I never heard any more about it.”

John Glenn enters his Friendship 7 spacecraft on On Feb. 20, 1962. Credit: NASA

– Fireflies. An extended sequence in The Right Stuff shows Glenn exclaiming as he sees “fireflies” outside of the spacecraft. The movie doesn’t really explain why they happen, but yes, they actually were there. “I saw around the capsule a huge field of particles that looked like tiny yellow stars,” Glenn wrote in his memoir. “They seemed to travel with the capsule, but more slowly. There were thousands of them, like swirling fireflies.” Glenn added: “They were droplets of frozen water vapor from the capsule’s heat exchanger system, but their fireflylike glow remains a mystery.” However, fellow astronaut Scott Carpenter noted frost flakes from his spacecraft, Aurora 7 on the next Mercury flight after Glenn’s, and floating nearby. They shone when the Sun illuminated the flakes. He also noticed more flakes coming off the side of his spacecraft when he banged the inside.

– Activities in orbit. While allowing that The Right Stuff probably had other priorities in mind, the movie does not show Glenn doing much in orbit besides gazing out the window and talking about the aforementioned fireflies. Glenn’s book shows him doing more than that: taking his blood pressure, snapping pictures of the Canaries and Sahara Desert, testing his vision, and doing exercises with a bungee cord to compare his readings to previous ones taken on the ground.

– Lights on in Perth and Rockingham, Australia. Glenn and a ground station in Australia chat about the residents of Rockingham and Perth turning on their lights for him. This actually did happen (and it happened again when Glenn returned to space in 1998.)

– Decision to bring Glenn down after three orbits. The movie accurately says Glenn was go for at least seven orbits, but then shows Glenn being confused when he’s told to come down after only three. Glenn contradicts that directly in his account: “The mission was planned for three orbits, but it meant that I could go for at least seven if I had to.”

The launch of John Glenn on Mercury 6. Credit: NASA

– Heat shield threat. The movie shows Mission Control grappling with a signal indication that the landing bag deployed, which implies that the heat shield might have cut loose prematurely. They recommend Glenn refrain from removing a retrorocket package that usually was jettisoned after the rockets fire for re-entry, and keep it on the spacecraft to hold the heat shield on. Glenn talks at length about the situation in his book, and expresses frustration that he didn’t receive information quickly: “I was irritated by the cat-and-mouse game they were playing with the information.” It turned out to be a false alarm.

– Humming. Glenn hums a lot in the movie during the re-entry, especially as the gravity forces build up on him. The astronaut makes no mention of doing so in his book. Long-standing New York Times space journalist John Noble Wilford unequivocally stated the movie was wrong: “Mr. Glenn did not hum ”The Battle Hymn of the Republic” during re-entry,” he wrote in a 1983 review of the movie.

February 20, 2013December 23, 2015 by Nancy Atkinson

Infographic: What’s the Difference Between a Comet, Asteroid and Meteor?

'Name That Space Rock' -- describes the difference between those flying rocks from space. Credit and copyright: Tim Lilis. Used by permission.

With all the various space rocks flying by and into Earth last Friday, perhaps you’ve been wondering about the correct terminology, since a rock from space has different names depending on what it is made of and where it is.

Infographics artist Tim Lillis has put together a primer of sorts, in the form of an infographic, describing the different between a comet, asteroid, meteoroid, meteor and meteorite.

Asteroids are generally larger chunks of rock that come from the asteroid belt located between the orbits of Mars and Jupiter. Sometimes their orbits get perturbed or altered and some asteroids end up coming closer to the Sun, and therefore closer to Earth.

Comets are much like asteroids, but might have a more ice, methane, ammonia, and other compounds that develop a fuzzy, cloud-like shell called a coma – as well as a tail — when it gets closer to the Sun. Comets are thought to originate from two different sources: Long-period comets (those which take more than 200 years to complete an orbit around the Sun) originate from the Oort Cloud. Short-period comets (those which take less than 200 years to complete an orbit around the Sun) originate from the Kuiper Belt.

Space debris smaller than an asteroid are called meteoroids. A meteoroid is a piece of interplanetary matter that is smaller than a kilometer and frequently only millimeters in size. Most meteoroids that enter the Earth’s atmosphere are so small that they vaporize completely and never reach the planet’s surface. And when they do enter Earth’s atmosphere, they gain a different name:

Meteors. Another name commonly used for a meteor is a shooting star. A meteor is the flash of light that we see in the night sky when a small chunk of interplanetary debris burns up as it passes through our atmosphere. “Meteor” refers to the flash of light caused by the debris, not the debris itself.

If any part of a meteoroid survives the fall through the atmosphere and lands on Earth, it is called a meteorite. Although the vast majority of meteorites are very small, their size can range from about a fraction of a gram (the size of a pebble) to 100 kilograms (220 lbs) or more (the size of a huge, life-destroying boulder).

Thanks again to Tim Lillis for sharing his infographic with Universe Today. For more info about Tim’s work, see his Behance page, Flickr site, Twitter, or his website.

February 20, 2013April 26, 2016 by David Dickinson

In Search of Darkness: the Battle Against Light Pollution

Where the dark skies are (and aren't). NASA image in the Public Domain courtesy of Marc Imhoff, Craig Mayhem & Robert Simon (NASA/GSFC) Christopher Elvidge(NOAA).

A good majority of modern Americans have never seen truly dark skies. I was fortunate to grow up in northern Maine in the 1970s with skies dark enough to see the summer Milky Way right from my doorstep. For most of the Eastern Seaboard of the United States, this is no longer the case. During the blackout brought on by Hurricane Sandy over the tri-state area in 2012 and after Hurricane Andrew hit Miami in 1992, many urbanites got to see an unfamiliar sight first hand; a dark night sky. There were even calls to 9/11 reporting fires on the horizon, which were in fact the Milky Way!

Do your skies look like this? (Photo by Author). — Do your skies look like this?
(Photo by Author).

In just over two weeks time on March 10^th, most of North America will “spring forward” once again to daylight savings time; three weeks afterwards on March 31^st, the European Union will follow suit.

For astronomers, this means waiting until the later evening hours for total darkness and late start times for star parties. If it seems like we spend more of the year on daylight savings time, we in fact do; the Energy Policy Act of 2005 mandates that daylight savings for most of the U.S. (a majority of Arizona is a staunch hold out) now starts on the second Sunday of March and runs until the first Sunday of November, or about 65% of the year. But discussions of DST’s utility or anachronism aside, it puts just one more hurdle between astronomers and what they love: dark skies.

Does your observatories' night sky look like this? (Photo by Author). — Observatory versus light pollution. (Photo by Author).

You can’t even see your hand in front of your face under truly dark skies. Such darkness is measured on what’s known as the Bortle Scale, with 1 being dark enough to notice air glow and phenomena like the Gegenschein, while 9 is a washed out inner-city night sky, with perhaps only the Moon and the brightest planets punching through the haze.

We once did a Bortle scale estimation while waiting for an airport shuttle on the Las Vegas strip; Vegas is arguably the most light-polluted locale on the planet. Jupiter, the Moon and the brightest stars of Orion could only be seen if you knew exactly where to look for them. In contrast, we’ve heard many service members remark about how splendid the sky looks from such deployed locations as Afghanistan.

A vanishing treasure; true dark skies. (Photo by Author).

The encroachment of civilization on wilderness areas also means that most school star parties and downtown observatories are restricted to bright targets, and serious deep sky observers must now drive several hours for a reasonably dark sky. Living just outside the Tampa/Saint Petersburg area in Florida, I can actually tell if it’s cloudy or clear at night just by how bright our bedroom appears with lights out. A cloudy sky reflects all the city lights back down, creating a “false dawn” that fills the room.

Dark sky sites are like secret fishing holes for backyard astronomers. Everyone knows of a few, some of which are even carefully hidden and discussed in hushed tones for fear of the light generating hordes which will descend upon them.

For dark skies in the Tampa Bay area, most observers head north to Chiefland along the Nature Coast about a two hour drive north. If you’ve got boat access, a truly dark sky locale can be had in the Dry Tortugas off of the Florida Keys to the south.

Dark Skies at Dunham Farms, Georgia (Photo by Author).

We recently visited such a hidden “dark sky island” in northern Georgia. Dunham Farms is a great old farmhouse Bed & Breakfast in Liberty County near Hinesville, Georgia. Despite how close as it is to Savanna, Dunham Farms sits in a “triangle of darkness,” a rarity along the Atlantic coast. We estimated the sky at a Bortle Scale of 2-3 while we were there doing nighttime astrophotography. Astronomy clubs in nearby Savanna also find dark sky requiem at nearby Tybee Pier, and further north, clubs such as the Midlands Astronomers based out of Melton Observatory in Columbia, South Carolina head to nearby Congaree Swamp.

And so it is along much of the U.S. East Coast, as observers must make to pilgrimage ever further inland in search of dark skies. Truth is, much of nighttime lighting is simply wasted energy headed skyward to illuminate the undersides of clouds and aircraft. Not only does this destroy our pristine night sky, but it’s also a threat to nocturnal wildlife and humans as well. Nigh-time lighting confuses migrating birds, often casuing them to fly into buildings. In 2009 the American Medical Association joined the fight against light pollution, citing it as a health risk. Light pollution effects our natural circadian rhythms, and studies show it may be linked to increased cancer rates as well. Turns out, our bodies need darkness.

But there is light (bad pun intended) at the end of the tunnel. Light pollution ordinances are now on the books in many municipalities. In 2001, the International Dark Sky Association recognized Flagstaff, Arizona as the first dark sky certified city. Increasingly, observatories around cities in Arizona such as Tucson and Flagstaff are being recognized as national scientific assets to be safeguarded.

Of course, legislation on the books is only as good as its enforcement. There are no “light pollution police” on the beat, and ordinances against “light trespass” are only put into practice when someone complains about it. We’ve found that frequently, inviting the neighbors over for a “backyard star party” can avoid having them install a World War II surplus anti-aircraft spotlight in their back yard to begin with… hey, that’s what your security light looks like to us!

And there’s nothing stopping hardware outlets from selling light fixtures that are illegal to install. A good fixture directs light downward where it’s needed. Lowes has recently launched its line of dark sky compliant outdoor lighting, and hey, if enough customers “vote with their wallets” more may follow suit. Its money saved in these cash strapped times, and a night sky gained!

February 19, 2013December 23, 2015 by Nancy Atkinson

Another Incredible Timelapse from the ISS

'The full moon rises over the only planet we have ever called home,' Tweeted astronaut Chris Hadfield.

We never get tired of these amazing views from the International Space Station, but this one has it all: a silvery Moon setting into the Earth’s atmosphere, the dazzling Milky Way rising into a brilliant sunrise, airglow of all colors, popping lightning, shimmering aurorae, and incredible views of the stunning space station and our gorgeous planet. Brian Tomlinson put this one together, using stills from the Johnson Space Center’s “Gateway to Astronaut Photography of the Earth.”

Below is a recent image taken by Canadian astronaut Chris Hadfield showing the Moon hovering above Earth, as seen from the ISS, similar to the views in the opening of the video:

February 19, 2013December 23, 2015 by Bob King

Bright New Supernova Shines in Southern Skies

New supernova 2013aa, discovered by Stu Parker on February 13, 2013, is southwest of the spiral galaxy NGC 5643 in the southern constellation Lupus. This photo was taken three days later. Credit: Joseph Brimacombe

I live in the frozen north by choice, but occasionally I yearn for warmer places like Tucson and Key West. These feelings usually start in late February, when after nearly four months of winter, the season feels endless. Today I wish I could head down south for another reason – to see a very bright supernova in a galaxy in Lupus.

SN 2013aa popped off in the barred spiral galaxy NGC 5643 in the constellation Lupus the Wolf 34 million years ago, but no one knew its light was wiggling its way across the cosmos to Earth until New Zealand amateur astronomer Stu Parker nailed it during one of his regular supernovae hunts. Parker recorded it on Feb. 13, 2013. Since it was so far from the galaxy, he thought at first it was a hot pixel (electronic artifact) or an asteroid. Another look at the galaxy 5 minutes later confirmed it was really there.

Good thing. It turned out upon confirmation to be the brightest supernova he and his band of supernova hunters had ever discovered.

Stu is a member of a 6-man amateur supernova search team from Australia and New Zealand called BOSS (Backyard Observatory Supernova Search). They’ve been working together since 2008 with the goal of searching for and reporting supernovae in the southern sky. When a member finds a candidate, they contact profession astronomers who follow up using large telescopes. To date the group has found 56 supernovae with Stu discovering or co-discovering 45 of them!

Map showing the sky looking south around 5 a.m. local time from Tuscon, Arizona. The new supernova in galaxy NGC 5643 is low in the southern sky before dawn for observers in the southern U.S. and points south. Created with Stellarium

From the northern U.S., much of Lupus and especially the supernova never make it above the horizon, but from about 35 degrees north and points south, SN 2013aa is fair game. The “new star” lies southwest of the core of galaxy NGC 5643, which shines at magnitude 10, bright enough to see in a 6-inch telescope from a dark sky. The supernovae is still climbing in brightness and today gleams at about 11.6 magnitude – no problem in that 6-inch if you’re equipped with a good map or photo to help get you there.

In this annotated version of the Joseph Brimacombe's photo, I've suggested a straightforward "star hop" from the galaxy's nucleus to the supernova. — In this annotated version of the Joseph Brimacombe’s photo, I’ve suggested a straightforward “star hop” from the galaxy’s core to 2013aa using brighter foreground stars.

Based on the study of 2013aa’s light, astronomers have classified it as Type Ia. Before the explosion, the star was a white dwarf, a superdense, planet-sized object with the mass of the sun. Tiny but mighty, the white dwarf’s powerful gravity pulled material from a nearby companion star down to its surface. When a dwarf puts on enough pounds to exceed 1.4 times the sun’s mass, the extra material increases the pressure and temperature of the core and the star burns explosively.

In a Type Ia supernova, a white dwarf (left) draws matter from a companion star until its mass hits a limit which leads to collapse and then explosion. — In a Type Ia supernova, a white dwarf (left) draws matter from a companion star until its mass hits a limit which leads to runaway burning and a catastrophic explosion that obliterates the star.

The energy released increases the star’s brightness to 5 billion times that of the sun. Matter from the blast streaks into space at speeds of 3,000-12,000 miles per second. Yes, this is a BIG deal and one of the most energetic events the universe has to offer. No wonder amateurs like myself can’t get enough of them.

NGC 5643 is best placed in the southern sky around 5 a.m. local time. From Lexington, KY. (latitude 38 degrees N.) it’s only 8 degrees high or slightly less than one fist held at arm’s length. Tuscon’s better at 14 degrees and Key West (latitude 25 N) best at 21. Farther south, your views will continue to improve. And the pleasant temperatures can’t hurt either.

You can start with the bright pair of Saturn and Spica midway up in the southern sky. Look about two outstretched fists below them to find Theta Centauri and from there “three fingers” to the lower left (southeast) to Eta Centauri. The galaxy is about 1 1/2 degrees southwest of Eta. The supernova will look like an 11 1/2 magnitude star 74″ west and 180″ south of the galaxy’s bright core. Use the annotated photo to help guide you straight to it.

To keep track of the 2013aa’s progress as well as view many more photos, I highly recommend David Bishop’s Latest Supernovae site.

February 19, 2013December 23, 2015 by Nancy Atkinson

First Radar Observations of Asteroid 2012 DA14

This collage of 72 individual radar-generated images of asteroid 2012 DA14 was created using data from NASA's 230-foot (70-meter) Deep Space Network antenna at Goldstone, Calif. Image credit: NASA/JPL-Caltech

The Jet Propulsion Laboratory has released an initial view of radar observations of asteroid 2012 DA14 generated from data obtained by NASA’s Goldstone Solar System Radar, taken on Feb. 15-16, 2013 as the asteroid headed away from Earth. While these first radar data aren’t very picturesque, they do reveal one obvious thing: this asteroid is tumbler.

The movie is comprised of 73 radar “images” looped nine times. JPL said that during the observations, the space rock’s distance increased from 120,000 to 314,000 km (74,000 to 195,000 miles) from Earth. The resolution here is 4 meters per pixel.

The images span close to eight hours and clearly show an elongated object undergoing roughly one full rotation. JPL said the images suggest that the asteroid has a long axis of about 40 meters (130 feet). The radar observations were led by scientists Lance Benner and Marina Brozovic of JPL. Additional Goldstone radar observations were taken as the asteroid continued to move away from Earth, on February 18, 19, with more observations scheduled on the 20th.

Radar is one of the best techniques for studying an asteroid’s size, shape, rotation state, surface features and surface roughness, and for improving calculations of its orbit. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than if radar observations weren’t available.

Source: JPL

February 19, 2013December 23, 2015 by Nancy Atkinson

Luckiest Photo Ever: The Moon, Jupiter … and More

'Fly Me to the Moons' -- a view of the Moon with Jupiter and the four Galilean moons, along with a passing airplane. Credit and copyright: Greg Gibbs.

“No matter how much you plan and prepare,” said photographer Greg Gibbs, “sometimes you just have to be very lucky.”

As we mentioned last week, Jupiter and the Moon were going to have a close encounter in the sky on February 18, with an occultation visible in some areas. And so Gibbs was preparing to get shots of the occultation through his telescope from his location in Victoria, Australia, and was using an automated timer to get shots at about 10 second intervals But then he noticed lights from a plane coming close to the Moon.

“I realised that there was a chance that it would pass in front of the Moon,” he said, “so I quickly canceled the remote timer I was using to take the shots and instead started shooting high speed continuous frames. I managed to get this plane crossing the moon in five individual frames just as Jupiter was about to be occulted by The Moon.”

This final product, as Gibbs notes on his Facebook page, is a two image composite. The Moon, Jupiter and the plane are all one single image. Then he took an overexposed image to bring up the Galilean Moons of (from left to right) Io, Callisto and Europa. At the time of this shot, Ganymede had already been occulted by The Moon.

There’s the old saying, “If you can’t be good, be lucky…”

This shot may have been lucky, but it sure is good, too!

See more of Gibbs astrophotography at his website, Capturing the Night.

Additionally, Peter Lake from Australia put together this video from last night’s occultation:

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.

February 19, 2013December 23, 2015 by Nancy Atkinson

Mission Control Loses Contact with International Space Station

The International Space Station. Credit: NASA

Today at about 9:45 a.m. EST (15:45 UTC) the International Space Station experienced a loss of communication with the Mission Control in Houston, and at this writing, communication has yet to be re-established. When communication was lost, flight controllers in Houston were updating the software onboard the station’s flight computers, and one of the station’s data relay systems malfunctioned. The primary computer that controls critical station functions defaulted to a backup computer, but was not allowing the station to communicate with NASA’s Tracking and Data Relay Satellites, NASA said.

Update: according to the Johnson Space Center Twitter feed, communications have been restored with the space station effective 11:34 am central time (17:34 UTC).

Flight controllers were able to communicate with the crew as the space station flew over Russian ground stations before 11:00 a.m. EST and instructed the crew to connect a backup computer to begin the process of restoring communications. Expedition 34 Commander Kevin Ford reported that the station’s status was fine and that the crew was doing well.

“Hey, just FYI, the station is still flying straight, everybody is in good shape, or course, and nothing unexpected except lots of caution and warning [alarms],” Ford said. “All the systems look like they are doing just fine.” Listen to the recording of his call here.

The loss occurred just prior to NASA TV’s regular broadcast of space station activities, and commentator Brandi Dean said, “We are able to see some data on the ground to let us know that everything is still good on the station and everything is going well with the procedures to re-establish communications with the ground.”

Dean said communication is expected to re-established within an hour, but we’ll provide updates if more problems persist.

In an uncanny coincidence (or prescience), Canadian astronaut Chris Hadfield Tweeted this morning, “Good Morning, Earth! Today we transition the Space Station’s main computers to a new software load. Nothing could possibly go wrong.”

February 19, 2013December 23, 2015 by Dan Majaess

Narrowing Down the Hunt for Giant Exoplanets

Despite advances in exoplanet research over the past decade much remains unknown. For example, how do the detection rates of giant planets vary as a function of the host star’s metal content? Are giant planets more frequent around massive stars? Do giant planets form under different mechanisms depending on the star’s metal content?

To that end a team of astronomers led by Annelies Mortier and Nuno C. Santos explored what mathematical function characterizes the detection rate across a distribution of stars (i.e., from metal-rich to metal-poor objects). “Finding the exact functional form of the metallicity-planet detection frequency will foster our understanding of both planet formation and the number of planets roaming the galaxy,” Santos told Universe Today.

Giant planets are most often found around metal-rich stars, and a figure from the team’s study (shown below) reaffirms that ~25% of stars featuring twice the Sun’s metal content host a giant planet, while the probability falls to ~5% for stars with a metal content analogous to the Sun.

Establishing that metal-rich stars exhibit an increased probability of hosting a giant planet constrains planet formation models. Specifically, the observations suggest that larger metallicity promotes the growth of rocky/icy cores, which subsequently accrete gas. However, the team notes that although the giant planet-metallicity trend is solid for stars exhibiting metallicities greater than (or analogous to) the Sun, the results are less certain for metal-poor stars. Indeed, there is an active debate in the literature pertaining to what function links the metal-rich and metal-poor regimes. In particular, does an exponential decline extend into the metal-poor regime, or does the function level off?

Depending on the manner in which the frequency trend extends into the metal-poor regime, it may indicate that a separate mechanism is responsible for creating that subsample’s giant planets. Thus continued surveys of metal-poor stars are important, despite the decreased frequency of finding a giant planet. Moreover, Mortier (Centro de Astrofisica, Universidade do Porto) notes that, “Studying metal-poor stars should be encouraged, since several theoretical models show that Earth-like planets are more common around these stars than around their metal-rich counterparts.”

Frequency of giant planets as a function of metallicity (A. Mortier et al., arXiv:1302.1851). — *Frequency of giant planets as a function of metallicity (credit: Mortier et al., arXiv 1302.1851).*

The team focused their efforts on trying to discern a difference between the viability of various functional forms in the metal-poor regime (i.e., does the detection rate of giant planets in that domain flatten, rather than decline exponentially?). In the end no statistical difference was found between the scenarios, and it was likewise unclear whether a mass-dependence exists behind the frequency of giant planet detections. The team noted that a larger sample was needed to reach definitive conclusions, and added that ongoing surveys to discover planets would ensure the problem may soon be resolved.

“Kepler and Gaia will significantly increase the amount of planet discoveries, not only for giant planets, but also for smaller planets,” said Mortier.

In sum, to answer the questions posed at the outset planet-hunting efforts should be focused on metal-poor and metal-rich stars, despite the former exhibiting a reduced frequency of giant planets. The team’s findings will appear in Astronomy & Astrophysics, and a preprint is available on arXiv. The results from the study are tied in part to observations acquired via the HARPS (High Accuracy Radial Velocity Planet Searcher) instrument, which is shown below.

*HARPS (High Accuracy Radial Velocity Planet Searcher) instrument (credit: ESO).*

February 19, 2013December 23, 2015 by Bob King

The Year of the Comets: Three Reasons Why 2013 Could be the Best Ever

Comet L4 Panstarrs photographed from Australia at dawn on Feb. 17, 2013 with a telephoto lens. A bright head and short tail are visible. Credit: Joseph Brimacombe

2013 could turn out to be a comet bonanza. No fewer than three of these long-tailed beauties are expected to brighten to naked eye visibility. Already Comet C/2011 L4 PANSTARRS has cracked that barrier. Sky watchers in Australia have watched it grow from a telescopic smudge to a beautiful binocular sight low above the horizon at both dusk and dawn. A few have even spotted it without optical aid in the past week. Excited reports of a bright, fan-shaped dust tail two full moon diameters long whet our appetite for what’s to come.

Recent brightness estimates indicate that the comet could be experiencing a surge or “second wind” after plateauing in brightness the past few weeks. If the current trend continues, PanSTARRS might reach 1st or 2nd magnitude or a little brighter than the stars of the Big Dipper when it first becomes visible to northern hemisphere sky watchers around March 7. That’s little more than two weeks away!

Comet Panstarrs will make its first appearance for northern hemisphere sky watchers around March 7 low in the western sky after sundown. Notice that the comet gets no higher than 10 degrees - about one fist held at arm's length - through much of the month. Illustration created using Chris Marriott's SkyMap software — Comet Panstarrs will make its first appearance for northern hemisphere sky watchers around March 7 low in the western sky after sundown. Notice that the comet gets no higher than 10 degrees – about one fist held at arm’s length – through much of the month. Illustration created using Chris Marriott’s SkyMap software

Every day between now and March 10, when PanSTARRS’ orbit takes it closest to the sun, the comet is expected to slowly increase in brightness. Later this month it disappears in the solar glare, but when it re-emerges into evening twilight around Thursday, March 7, northern and southern hemisphere observers alike will get great views. Binoculars should easily show a bright head and swept-back tail pointing away from the sun. And don’t forget to mark your calendar for March 12. On that date the thin lunar crescent will join the comet for a rare photogenic pairing. To locate and keep track of PanSTARRS, you’ll need the following materials and circumstances:

* An unobstructed view of the western horizon
* Clear, haze-free skies at dusk
* Pair of binoculars
* A map

I can’t help you with all of the above, but this map will help point you in the right direction. Once you find a location with a great western view, watch just above the horizon for a fuzzy, star-like object in your binoculars. While it’s possible the comet will be bright enough to see with the naked eye, binoculars will make finding it much easier. They’ll also reveal details of tail structure too subtle to be visible otherwise.

Incredible detail is seen in the gas tail of F6 Lemmon in this photo made with a 19.6-inch telescope Feb. 17, 2013. Credit: Martin Mobberley

Comet PanSTARRS has some cometary company. C/2012 F6 Lemmon is currently plying its way through the constellation Tucana the Toucan, shining right around the naked eye limit at magnitude 5.5. To the unaided eye, Lemmon looks like a dim fuzzy spot. Binoculars show a thin gas tail and big, bright head or coma. Comas develop around the comet’s icy nucleus as sunlight vaporizes dusty ice to create a short-lived atmosphere that in the shape of a luminous teardrop. Long-exposures like the one above reveal richly-detailed streamers of carbon monoxide and other gases fluorescing in sunlight in the comet’s fashionably skinny tail.

Lemmon is slowly receding from Earth this month, but should remain just above the naked eye limit for some time as it continues to approach the sun. Northern hemisphere observers will need to be patient to see this one. After looping around the sun on March 24, the comet will pop back into the morning sky near the familiar Square of Pegasus asterism in early May. If we’re lucky, Lemmon may still be near the naked eye limit and visible in ordinary binoculars.

Cmet C/2012 F6 (Lemmon), imaged on Feb. 19. 2013 remotely from Q62 (iTelescope Observatory, Siding Spring). Credit: Ernesto Guido and Nick Howes, Remanzacco Observatory. — Cmet C/2012 F6 (Lemmon), imaged on
Feb. 19. 2013 remotely from Q62 (iTelescope Observatory, Siding Spring). Credit: Ernesto Guido and Nick Howes, Remanzacco Observatory.

Before we move on to the comet with the greatest expectations, I want to mention Comet 2P/Encke. Encke was the only the second comet to have its orbit computed – way back in 1819 by German astronomer Johann Encke. This year it’s making its 62nd observed return to Earth’s vicinity. That’s a lot of visits, but when your orbital period is only 3.3 years – the shortest known of any comet – you can’t help but be a regular visitor. While not expected to brighten to naked eye level, the comet will be a fine sight in modest-sized telescopes glowing around 8th magnitude when it tracks between the Big Dipper and Leo the Lion this October.

Comet ISON in the western sky shortly after sunset in late November this year. Illustration created with Chris Marriott's SkyMap software — Comet ISON in the western sky shortly after sunset in late November this year. Illustration created with Chris Marriott’s SkyMap software

Our final comet, Comet C/2012 S1 ISON, was discovered last September by Russian amateurs Vitali Nevski and Artyom Novichonok while making observations for the International Scientific Optical Network (ISON). At the time, it was farther than Jupiter and impossibly faint, but once ISON’s orbit was determined, astronomers realized the comet would pass only 1.1 million miles from center of the sun (680,000 miles above its surface) on November 28, 2013.

Comet ISON belongs to a special category of comets called sungrazers. As the comet performs a hairpin turn around the sun on that date, its ices will vaporize furiously in the intense solar heat. Assuming it defies death by evaporation, ISON is expected to become a brilliant object perhaps 10 times brighter than Venus. Or brighter. Some predict it could put the full moon to shame. If so, that would occur for a brief time around at perihelion (closest approach to the sun) when the comet would only be visible in the daytime sky very close to the sun. When safely viewed, ISON might look like a brilliant, fuzzy star in a blue sky.

A color image of comet Ison taken on February 5, 2013 from northern Arizona. Credit: Chris Schur.

Most of us won’t risk burning our retinas staring so close to sun. Instead we’ll watch with anticipation as the comet sprouts a long tail while ascending from the western horizon just after sunset in late November and early December. Whatever it does, sky watchers in both southern and northern hemispheres will ringside seats when ISON’s at its best.

Right now the comet’s whiling away its time in the constellation Gemini the Twin and still very faint. Come September, it should be easily visible in small telescopes in the morning sky. The first naked eye sightings could happen in late October. Many of us hope the comet will be one for the record books, a worthy successor to C/2006 P1 McNaught, the last “great comet” to dazzle human eyes. It reached peak magnificence for southern hemisphere sky watchers in January 2007.

C/2006 P1 McNaught became a memorable sight for observers living in southern latitudes in January 2007. Will Comet ISON do the same? Credit: Wikipedia

Three bright comets – and one modestly bright – might be enough for a year, but there could be surprises. Dozens of new comets are discovered each year by professional sky surveys and amateur astronomers. Most are faint and move along their appointed paths unnoticed by 99.9% of the world’s population, but every so often a new one comes along that blossoms into a spectacle. How many of those are out there tonight waiting to be discovered?