GALLERY: Solar blast

A CORONAL MASS EJECTION, or CME, has been spotted erupting away from the Sun, in images taken by the Solar and Heliospheric Observatory (SOHO) spacecraft.

According to the SOHO web site, a CME is a “huge magnetic bubble of plasma that erupts from the Sun’s corona and travels through space at high speed.” Plasma is gas that has been ” heated to sufficiently high temperatures that the atoms ionise”.

When a CME occurs, the plasma shoots out into space and travels through the Solar System. If the timing is right (or wrong, depending on your point of view), a CME can head directly toward Earth.

The first image is a wide field, showing the CME in action on January 14, 2014. The Sun has been blocked out in order to show detail in its outer atmosphere. (The white circle shows the size of the Sun – 1.4 million kilometres, or 870,00 thousand miles, in diameter.) The bright point of light in the top right is the planet Venus. (The white flare on either side of Venus is not real; it is an artifact of the imaging process.)

The second image shows a slightly narrower field, again with the Sun blocked out.

SOHO coronograph image of a CME

A SOHO image of a coronal mass ejection spotted on January 14, 2014. The bright spot in the upper right corner is the planet Venus.

SOHO coronograph image of a CME

Another SOHO view of the January 14, 2014 coronal mass ejection.

SOHO orbits the Sun at a special location between the Sun and the Earth called the L1 Lagrange point. At this location, the gravity of the Sun and Earth balances out, enabling the spacecraft to circle the Sun while always staying on a line between Earth and Sun. It is owned and operated jointly by NASA and the European Space Agency.

Adapted from information issued by NASA and ESA.

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Lone star has two planets

A NEW GIANT PLANET has been located in a star system about 250 light-years from Earth. The planet, perhaps twice the mass of Jupiter, could help researchers learn more about how extrasolar planets are formed.

An extrasolar (‘beyond the Solar System’) planet is one that belongs to a star system other than our own.

The star system harbouring the new planet contains only one star, as do the other three systems with extrasolar planets analysed by San Francisco State University astronomer Stephen Kane, an assistant professor of physics and astronomy, and his colleagues. It is a surprising finding, given the high rate of multiple-star systems in our solar neighbourhood.

“There is a great interest in these stars that are known to host planets,” Kane explained, since astronomers suspect that planet formation in a multi-star system would be very different from planet formation in a single-star system like our own.

False-colour image of star HD 4230

This false-colour image shows the star HD 4230, located about 250 light-years from Earth. Measurements indicate the presence of two, unseen, planets orbiting it.

A multiple-star system “might have not one but two” flattened clouds, called discs, where planets form, he said. “Or it could be that having an extra star would be disruptive, and its gravity could cause any protoplanets to pull apart.”

Relatively few extrasolar planets have been found in multiple-star systems, “but we know that they are there,” Kane said.

A wobbling star

In the four systems studied by the researchers, using optical imaging data collected at the Gemini North observatory in Hawaii, there were some intriguing signs that perhaps a second star – or something else – was present.

In each system, the extrasolar planets were discovered by the radial velocity technique, which measures variations in the speed at which a star moves away and toward Earth, “wobbled” by the gravitational pull of a nearby cosmic body. Depending on the radial velocity signature, astronomers can calculate whether the wobble is coming from a planet or star.

In the star systems studied by Kane and his colleagues, there was a part of the radial velocity data that couldn’t be explained entirely by the pull of an orbiting planet. And at the same time, the planets that had already been discovered in these systems followed eccentric orbits, swinging away from their stars in a less circular and more elliptical fashion, “more like that of a comet,” Kane said.

An unexplained velocity

With these two clues, the researchers wondered if the radial velocity and eccentric orbits might be explained by the presence of another star in the system. But when they took a closer look at the systems, they were able to rule out the possibility that another star was perturbing the system.

Depiction of planetary orbits around HD 168443

The two solid circles marked b and c, depict the orbits of planets circling HD 168443, one of the stars studied by Stephen Kane and his colleagues. The dashed circles represent the size of the orbits of Mercury, Venus Earth and Mars in our Solar System.

“I thought we were likely to find stellar companions, and when all four didn’t have a binary star, that did surprise me,” Kane said.

But in the case of one star, HD 4230, the unexplained radial velocity appears to be coming from the pull of a previously undiscovered giant planet, the researchers report. They confirmed the planet’s presence with additional radial velocity data collected at Hawaii’s Keck observatory.

Given that the researchers did not find any stellar companions, Kane says it is very likely that the leftover radial velocity is instead a signal that there are additional planets to be found in all four systems. The researchers feel this is especially true for the system called HD 168443, where their ability to detect a companion star was very strong.

Adapted from information issued by San Francisco State University.

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Australian astronomer wins prestigious award

THE 2014 GROTE REBER MEDAL for innovative and significant contributions to radio astronomy has be awarded to Professor Ron Ekers of Australia. Professor Ekers was the Foundation Director of CSIRO’s Australia Telescope National Facility at Narrabri, and is a former director of the Very Large Array in New Mexico, USA, operated by the National Radio Astronomy Observatory (NRAO).

He is currently a CSIRO Fellow at the Australia Telescope National Facility (ATNF), CSIRO Division of Astronomy and Space Science in Australia, and Adjunct Professor at Curtin University in Perth and the Raman Research Institute in Bangalore, India.

Headshot of Ron Ekers

Professor Ron Ekers

The Grote Reber Medal is named after a pioneer of radio astronomy (see below).

Ekers is being recognised for his many pioneering scientific radio astronomy investigations, which extend over half a century. Working with various colleagues, Ekers studied galaxies, made precise measurements of the way the Sun’s gravity deflects radio waves, made some of the first high-resolution images of the centre of the Galaxy at radio wavelengths, and critical early observations of pulsars.

More recently he is leading a project to detect radio emission resulting from ultra high-energy neutrino interactions with the Moon.

Ekers also played a key role in developing what was probably the first interactive computer language for analysing radio astronomy images. In the mid-1990s he became the strongest force in advocating support for the international Square Kilometre Array initiative.

“Over a career lasting nearly half a century Ron Ekers has worked in almost every area of radio astronomy. As a strong believer in international collaboration, he was the earliest advocate for the Square Kilometre Array, and perhaps, more than anyone else, he was responsible for building the current level of international support for the SKA”, said Dr Ken Kellermann of the NRAO.

“Ron is the complete internationalist and has contributed significantly to the major radio astronomy instruments in Europe, the US and Australia,” said Dr David Jauncey, CSIRO Astronomy and Space Science Affiliate and ANU Visiting Fellow.

The medal will be presented to Professor Ekers during the 31st General Assembly of the International Union of Radio Science to be held in Beijing, China in August, 2014.

About Grote Reber

Grote Reber was born on 22 December 1911. Before he was 30 years of age, he became the world’s first radio astronomer. In 1937, constructed the world’s first purpose-built radio telescope, adjacent to his home in Wheaton, Illinois, just west of Chicago. Reber’s telescope was the forerunner of the classic design of the world’s famous radio telescopes (including the famous ‘dish’ at Parkes, in Australia). The same principle is used widely today in many other applications, including satellite dishes in private homes.

Reber used his telescope to make the first detailed radio map of the sky. “His work was a huge step forward for astronomy”, said Martin George, Administrator of the Grote Reber Medal. “For the first time, the Universe was being studied at wavelengths other than those visible to our eyes.”

Grote Reber using radio equipment

Grote Reber

In 1954, Reber moved to Tasmania, Australia, where he began observing at very much longer wavelengths using a quite different type of ‘telescope’: an array of dipoles, which took the form of antennas strung between the tops of poles.

Reber constructed an array that covered an area of one square kilometre. Although now dismantled, in terms of collecting area it still holds the record for the world’s largest single radio telescope ever constructed.

Although Reber’s research and ideas often fell outside the mainstream activities of other astronomers, his contributions, especially in the early days of radio astronomy, were both pioneering and critically important. He was awarded a number of prizes and an honorary Doctor of Science Degree from Ohio State University in the USA.

“Grote Reber’s achievements showed, most importantly, that one person can make a difference”, said Dr David Jauncey.

Grote Reber died in Tasmania on 20 December 2002, two days before his 91st birthday.

Adapted from information issued by Trustees of the Grote Reber Foundation. Ron Ekers and ATCA photos courtesy of CSIRO Astronomy and Space Science. Grote Reber photo courtesy NRAO.

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2014 astronomy and space calendars

IT’S NOT TOO LATE to grab one of these beautiful 2014 astronomy and space exploration calendars. We’ve selected more than 20 of the best from around the world. From Hubble’s latest images, to planets, deep space nebulae, aurorae (northern and southern lights), and even one from astronauts aboard the space station (a crew that included the pop star of astronomers, Canadian Chris Hadfield). They’re all available right now through the SpaceInfo Shop at www.spaceinfo.com.au/astrocalendars.html

Montage of space calendars

All over these calendars are available now from the SpaceInfo Shop – www.SpaceInfo.com.au

A stellar dust factory

STRIKING NEW OBSERVATIONS with the Atacama Large Millimetre/submillimetre Array (ALMA) telescope capture, for the first time, the remains of a recent supernova brimming with freshly formed dust. If enough of this dust makes the perilous transition into interstellar space, it could explain how many galaxies acquired their dusty, dusky appearance.

Cosmic dust consists of silicate and graphite grains – minerals also abundant on Earth. The soot from a candle is very similar to cosmic graphite dust, although the size of the grains in the soot are ten or more times bigger than typical grain sizes of cosmic graphite grains.

This image shows the remnant of Supernova 1987A

This image shows the remnant of Supernova 1987A seen in light of very different wavelengths. ALMA data (in red) shows newly formed dust in the middle of the remnant. Hubble Space Telescope (in green) and Chandra Space Observatory (in blue) data show the expanding shock wave. Credit: ALMA (ESO/NAOJ/NRAO) / A. Angelich. Visible light image: the NASA/ESA Hubble Space Telescope. X-Ray image: The NASA Chandra X-Ray Observatory

Galaxies can be remarkably dusty places and supernovae – exploded stars – are thought to be a primary source of that dust, especially in the early universe. But direct evidence of a supernova’s dust-making capabilities has been slim up to now, and could not account for the copious amount of dust detected in young, distant galaxies. But now observations with ALMA are changing that.

An international team of astronomers used ALMA to observe the glowing remains of Supernova 1987A, which is in the Large Magellanic Cloud, a dwarf galaxy orbiting the Milky Way about 160,000 light-years from Earth. SN 1987A is the closest observed supernova explosion since Johannes Kepler’s observation of a supernova inside the Milky Way in 1604. Being far in the southern sky, it is clearly visible only from the Southern Hemisphere.

The Tarantula Nebula and its surroundings

This is an image of the Tarantula Nebula and its surroundings in the Large Magellanic Cloud galaxy, taken in 1987. Supernova 1987A is the bright star just to the right of centre. Credit: ESO

“This is the first time we’ve been able to really image where the dust has formed, which is important in understanding the evolution of galaxies,” said Remy Indebetouw, an astronomer at the National Radio Astronomy Observatory (NRAO) and the University of Virginia, both in Charlottesville, USA

Astronomers predicted that as the gas cooled after the explosion, large amounts of dust would form as atoms of oxygen, carbon, and silicon bonded together in the cold central regions of the remnant. However, earlier observations of SN 1987A with infrared telescopes, made during the first 500 days after the explosion, detected only a small amount of hot dust.

With ALMA’s resolution and sensitivity, the team was able to image the far more abundant cold dust, which glows brightly in millimetre and submillimetre light. The astronomers estimate that the remnant cloud now contains about 25 percent the mass of the Sun in newly formed dust. They also found that significant amounts of carbon monoxide and silicon monoxide have formed.

Aerial view of dishes of the Atacama Large Millimetre/submillimetre Array

Aerial view of dishes of the Atacama Large Millimetre/submillimetre Array (ALMA) telescope. Credit: ALMA

“SN 1987A is a special place since it hasn’t mixed with the surrounding environment, so what we see there was made there,” said Indebetouw. “The new ALMA results, which are the first of their kind, reveal a supernova remnant chock full of material that simply did not exist a few decades ago.”

There’s more information on Supernova 1987A, including an interview with Australian astronomers, on the ABC’s web site.

Adapted from information issued by NRAO.

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Five new rocky planets discovered

MORE THAN THREE-QUARTERS of the planet candidates discovered by NASA’s Kepler spacecraft have sizes ranging from that of Earth to that of Neptune, which is nearly four times as big as Earth. Such planets dominate the galactic census but are not represented in our own Solar System. Astronomers don’t know how they form or if they are made of rock, water or gas.

The Kepler team has today reported on four years of ground-based telescope follow-up observations targeting Kepler’s exoplanet systems (ie. planets beyond our Solar System) at the American Astronomical Society meeting in Washington. These observations confirm the numerous Kepler discoveries are indeed planets and yield mass measurements of these enigmatic worlds that vary between Earth and Neptune in size.

Included in the findings are five new rocky planets ranging in size from ten to eighty percent larger than Earth. Two of the new rocky worlds, dubbed Kepler-99b and Kepler-406b, are both forty percent larger in size than Earth and have a density similar to lead. The planets orbit their host stars in less than five and three days respectively, making these worlds too hot for life as we know it.

Artist's impression of an exoplanet

Astronomers have used ground-based telescopes to do follow-up observations of exoplanets detected by NASA’s Kepler space observatory. They’ve confirmed that many are between the Earth and Neptune in size. (Artist’s impression courtesy of NASA Ames / JPL-Caltech / Tim Pyle.)

Wobbly measurements

A major component of the follow-up observations were Doppler measurements of the planets’ host stars. The team measured the wobble of the host star, caused by the gravitational tug on the star exerted by the orbiting planet. That measured wobble reveals the mass of the planet: the higher the mass of the planet, the greater the gravitational tug on the star and hence the greater the wobble.

“This marvellous avalanche of information about the mini-Neptune planets is telling us about their core-envelope structure, not unlike a peach with its pit and fruit,” said Geoff Marcy, professor of astronomy at University of California, Berkeley who led the summary analysis of the high-precision Doppler study. “We now face daunting questions about how these enigmas formed and why our Solar System is devoid of the most populous residents in the galaxy.”

Artist's impression of exoplanets orbiting a red star

Artist’s impression of several exoplanets orbiting a red star. Courtesy ESO.

Using one of the world’s largest ground-based telescopes at the W. M. Keck Observatory in Hawaii, scientists confirmed 41 of the exoplanets discovered by Kepler and determined the masses of 16. With the mass and diameter in-hand, scientists could immediately determine the density of the planets, characterising them as rocky or gaseous, or mixtures of the two.

These density measurements dictate the possible chemical composition of these strange, but ubiquitous planets. The density measurements suggest that those planets smaller than Neptune – or mini-Neptunes – have a rocky core, but the proportions of hydrogen, helium and hydrogen-rich molecules in the envelope surrounding that core vary dramatically, with some having no envelope at all.

One step closer

A complementary technique used to determine mass, and in turn density of a planet, is by measuring the transit timing variations (TTV). Much like the gravitational force of a planet on its star, neighbouring planets can tug on one another causing one planet to accelerate and another planet to decelerate along its orbit.

Ji-Wei Xie of the University of Toronto, used TTV to validate 15 pairs of Kepler planets ranging from Earth-sized to a little larger than Neptune. Xie measured masses of 30 planets thereby adding to the compendium of planetary characteristics for this new class of planets.

“Kepler’s primary objective is to determine the prevalence of planets of varying sizes and orbits. Of particular interest to the search for life is the prevalence of Earth-sized planets in the habitable zone,” said Natalie Batalha, Kepler mission scientist at NASA’s Ames Research Centre. “But the question in the back of our minds is: are all planets the size of Earth rocky? Might some be scaled-down versions of icy Neptunes or steamy water worlds? What fraction are recognisable as kin of our rocky, terrestrial globe?”

Artist's impression of the Kepler space observatory

Artist’s impression of the Kepler space observatory. Courtesy NASA / Wendy Stenzel.

The mass measurements produced by Doppler and TTV hint that a large fraction of planets smaller than 1.5 times the radius of Earth may be comprised of the rocky silicates, iron, nickel and magnesium that are found in the terrestrial planets (Mercury, Venus, Earth and Mars) here in the Solar System.

Armed with this type of information, scientists will be able to turn the fraction of stars harbouring Earth-sizes planets into the fraction of stars harbouring bona-fide rocky planets. And that’s a step closer to finding a habitable environment beyond the Solar System.

Adapted from information issued by NASA.

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Some stars have split personalities

USING THE NEW CAPABILITIES of the upgraded Karl G. Jansky Very Large Array (VLA) radio telescope system, scientists have discovered previously-unseen companions to a pair of very young protostars. The discovery gives strong support for one of the competing explanations for how double-star systems form.

Astronomers know that about half of all Sun-like stars are members of double or multiple-star systems, but have debated over how such systems are formed.

artist's impression shows a disc of dust and gas surrounding a star

This artist’s impression shows a disc of dust and gas surrounding a star that is still in the process of formation. Evidence suggests that such discs sometimes split, leading to the formation of two or more stars. Image courtesy ESO / L. Calçada.

“The only way to resolve the debate is to observe very young stellar systems and catch them in the act of formation,” said John Tobin, of the National Radio Astronomy Observatory (NRAO). “That’s what we’ve done with the stars we observed, and we got valuable new clues from them,” he added.

Their new clues support the idea that double-star systems form when a flat cloud, called a disc, of gas and dust whirling around one young stars splits, forming another new star in orbit with the first. Astronomers call it the disc fragmentation model.

Fits the model

When Tobin and an international team of astronomers studied gas-enshrouded young stars roughly 1,000 light-years from Earth, they found that two had previously-unseen companions in the plane where their discs would be expected. One of the systems also clearly had a disc surrounding both young stars.

“This fits the theoretical model of companions forming from fragmentation in the disk,” Tobin said. “This configuration would not be required by alternative explanations,” he added.

Aerial view of VLA dishes in a Y-shape

Dishes of the Karl G. Jansky Very Large Array. NRAO image.

The new observations add to a growing body of evidence supporting the disc-fragmentation idea. In 2006, a different VLA observing team found an orbiting pair of young stars, each of which was surrounded by a disc of material. The two discs, they found, were aligned with each other in the same plane. Last year, Tobin and his colleagues found a large disc forming around a protostar in the initial phases of formation. This showed that discs are present early in the star formation process, a necessity for binary pairs to form through disc fragmentation.

“Our new findings, combined with the earlier data, make disc fragmentation the strongest explanation for how close multiple star systems are formed,” said Leslie Looney of NRAO and the University of Illinois.

Adapted from information issued by NRAO.

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The Crab Nebula

WHEN A MASSIVE STAR EXPLODES at the end of its life, the shattered remains become known as a supernova remnant. The one shown here is called the Crab Nebula.

This is a composite view produced with data from two telescopes: the Herschel Space Observatory and the Hubble Space Telescope. Herschel is a European Space Agency (ESA) mission with important NASA contributions, and Hubble is a NASA mission with important ESA contributions.

A wispy and filamentary cloud of gas and dust, the Crab Nebula is the remnant of a supernova explosion that was observed by Chinese astronomers in the year 1054.

The Crab Nebula

A new view of the Crab Nebula, a supernova remnant, using data gathered by the Herschel Space Observatory and the Hubble Space Telescope.

The image combines Hubble’s view of the nebula at visible wavelengths, obtained using three different filters sensitive to the emission from oxygen and sulphur ions (both shown here in blue). Herschel’s far-infrared image (shown here in red) reveals the emission from dust in the nebula.

While studying the dust content of the Crab Nebula with Herschel, a team of astronomers have detected emission lines from argon hydride, a molecular ion containing the noble gas argon. This is the first detection of a noble-gas based compound in space.

At the heart of the nebula is the Crab Pulsar, a rapidly spinning neutron star that emits a beam of radio waves. As the pulsar spins, the beam sweeps across the field of view as seen from Earth (a pure fluke, as it could have been pointed in any other direction).

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Words and image adapted from information issued by ESA / Herschel / PACS / MESS Key Programme Supernova Remnant  Team; NASA, ESA and Allison Loll / Jeff Hester (Arizona State University).

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Cloudy weather on an alien world

WEATHER FORECASTERS on exoplanet GJ 1214b would have an easy job. Today’s forecast: cloudy. Tomorrow: overcast. Extended outlook: more clouds.

The planet, which is known as GJ 1214b, is classified as a super-Earth because its mass is intermediate between that of Earth and Neptune. Recent searches for planets orbiting other stars (‘exoplanets‘) have shown that super-Earths like GJ 1214b are among the most common type of planets in the Milky Way galaxy. Because no such planets exist in our Solar System, the physical nature of super-Earths is largely unknown.

Previous studies of GJ 1214b yielded two possible interpretations of the planet’s atmosphere: it could consist entirely of water vapour or some other type of heavy molecule, or it could contain high-altitude clouds that prevent the observation of what lies underneath.

Artist's view of exoplanet GJ 1214b

An artist’s view of exoplanet GJ 1214b. The weather forecast is for cloudy skies.

But now a team of astronomers led by Laura Kreidberg and Jacob Bean of the Department of Astronomy and Astrophysics at the University of Chicago, have detected clear evidence of clouds in the atmosphere of GJ 1214b from data collected with the Hubble Space Telescope. The Hubble observations used 96 hours of telescope time spread over 11 months. This was the largest Hubble programme ever devoted to studying a single exoplanet.

The researchers describe their work as an important milestone on the road to identifying potentially habitable, Earth-like planets beyond our Solar System. The results appear in the January 2 issue of the journal Nature.

Pushing the limits

“We really pushed the limits of what is possible with Hubble to make this measurement,” said Kreidberg, a third-year graduate student and first author of the new paper. “This advance lays the foundation for characterising other Earths with similar techniques.”

“I think it’s very exciting that we can use a telescope like Hubble that was never designed with this in mind, do these kinds of observations with such exquisite precision, and really nail down some property of a small planet orbiting a distant star,” explained Bean, an assistant professor and the project’s principal investigator.

GJ 1214b is located just 40 light-years from Earth, in the direction of the constellation Ophiuchus. Because of its proximity to our Solar System and the small size of its host star, GJ 1214b is the most easily observed of the known super-Earths. It transits, or passes in front of its parent star, every 38 hours, giving scientists an opportunity to study its atmosphere as starlight filters through it.

Kreidberg, Bean and their colleagues used Hubble to precisely measure the spectrum of GJ 1214b in near-infrared light, finding what they consider definitive evidence of high clouds blanketing the planet. These clouds hide any information about the composition and behaviour of the lower atmosphere and surface.

Four planets in a row

An artist’s rendering comparing the size of GJ 1214b, another, larger exoplanet, and Earth and Neptune.

Unearthly weather

The planet was discovered in 2009 by the MEarth Project, which monitors 2,000 red dwarf stars for transiting planets. The planet was next targeted for follow-up observations to characterise its atmosphere. The first spectra, which were obtained by Bean in 2010 using a ground-based telescope, suggested that the planet’s atmosphere either was predominantly water vapour or hydrogen-dominated with high-altitude clouds.

More precise Hubble observations made in 2012 and 2013 enabled the team to distinguish between these two scenarios. The news is about what they didn’t find. The Hubble spectra revealed no chemical fingerprints whatsoever in the planet’s atmosphere. This allowed the astronomers to rule out cloud-free atmospheres made of water vapour, methane, nitrogen, carbon monoxide, or carbon dioxide.

The best explanation for the new data is that there are high-altitude clouds in the atmosphere of the planet, though their composition is unknown. Models of super-Earth atmospheres predict clouds could be made out of potassium chloride or zinc sulphide at the scorching temperatures of 230 degrees Celsius found on GJ 1214b. “You would expect very different kinds of clouds to form than you would expect, say, on Earth,” Kreidberg said.

The launch of NASA’s next major space telescope, the James Webb Space Telescope (JWST), later this decade should reveal more about such worlds, Kreidberg said. “Looking forward, JWST will be transformative,” she said. “The new capabilities of this telescope will allow us to peer through the clouds on planets like GJ 1214b. But more than that, it may open the door to studies of Earth-like planets around nearby stars.”

Adapted from information issued by the University of Chicago. Images courtesy NASA, ESA and G. Bacon.

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What’s up? The night sky for January 2014

WHEN STARTING OUT IN STARGAZING, most people are particularly keen to spot the planets, five of which are visible to the naked eye – Mercury, Venus, Mars, Jupiter and Saturn. The problem is that, to the novice, planets and stars look pretty much alike. An easy way to identify planets is to find them in relation to nearby bright stars or the Moon, and then watch as they change their positions slightly as each night passes. The information below will help you spot planets using this method.

Except where indicated, all of the phenomena described here can be seen with the unaided eye. Dates and times are for the Australian Eastern Summer Time zone, and sky directions are from the point of view of an observer at mid latitudes in the Southern Hemisphere.

People stargazing using a telescope

There’s plenty to see in the night sky during January 2014.

Jan 1

The Moon is in its ‘new’ phase (the opposite of ‘full’) tonight at 10:14pm. This means that, seen from Earth, it is in the same direction as the Sun, and therefore won’t be seen all night – which is good for stargazing, as the absence of its light will make fainter objects easier to see.

Jan 2

Today at 8:01am, the Moon will be at the closest point – called perigee – in its elliptical orbit around the Earth. The distance between the centres of the two bodies will be 356,921 kilometres.

Jan 4

Today the Earth reaches perihelion, which is the point at which our planet is closest to the Sun during its orbit. The distance separating the two bodies is 147,089,638 kilometres. Note the similarity between the words perigee and perihelion – perigee is used for anything orbiting the Earth (‘peri’ coming from the Greek for ‘around’, while the ‘gee’ part derives from gaia, the Greek word for Earth), while perihelion is used for anything orbiting the Sun (the ‘helion’ part coming from ‘Helios’, the ancient Greek god of the Sun).

There’s a common misconception that the Earth’s changing distance from the Sun (it varies from about 147 million to roughly 152 million kilometres over the course of the year) is responsible for giving us our summers and winters. This is wrong, and a few moments thought shows why. Taking perihelion as an example, the misconception says that with the Earth being at its closest point to the Sun, our planet should experience summer. Well, it’s certainly true that perihelion occurs when it is summertime in the Southern Hemisphere… but what season is it in the Northern Hemisphere? It’s winter. And why is it winter and not summer? Because perihelion has nothing to do with our seasons. The seasons are caused by the tilt of the Earth’s axis of rotation, which sees the Southern Hemisphere tilted toward the Sun at the end of the calendar year, and the Northern Hemisphere tilted away. Six months later it’s the other way around – the north is tilted toward the Sun (and thus the northern summer and southern winter are in the middle of the calendar year) and the south is tilted away.

Jan 8

It is first quarter Moon today at 2:39pm. A few days either side of first quarter is a good time to look at the Moon through a telescope, as the sunlight angle means the craters and mountains throw nice shadows, making it easier to get that 3D effect.

Jan 12

Tonight, the almost-full Moon will be just below the star Aldebaran, the brightest star in the constellation Taurus. Aldebaran is a red giant star roughly 44 times as big as the Sun, located about 65 light-years from Earth. Have a look to the left of Aldebaran and you’ll see a beautiful, broad group of stars in a V-shape. These are the Hyades. If you have a pair of binoculars, take a look; you’ll be amazed by the beautiful sight of these sparkling stars! (A little further to the left, or west, is an even more beautiful cluster of stars – the Pleiades. See the diagram for its location.)

Diagram of the night sky for January 12

The Moon will be near the star Aldebaran on the evening of January 12. Just above and to the left of Aldebaran is a group of stars called the Hyades – take a look with a pair of binoculars; it’s a beautiful sight. An even better cluster of stars, the Pleiades, is a little further to the left (or west). Below and to the right in this view is the planet Jupiter – the Moon will be close to it on January 15.

Jan 15

Tonight the almost-full Moon will be just above and to the right of what looks like a very bright star, but is in fact the planet Jupiter – the largest planet in our Solar System. If you have a decent pair of binoculars (ie. anything bigger than opera glasses), train them on Jupiter and you should be able to see its shape and perhaps even some of the ‘banding’ of the atmosphere (the planet’s different weather zones). You should also be able to see up to four tiny, bright pinpricks of light – these are the famous moons discovered by Galileo. You might see one or two on one side of Jupiter, and the others on the other side. (If you take a look in the late evening on January 18, you’ll see them all on the same side.)

Jan 16

Full Moon occurs today at 3:52pm. When the Moon is full, it rises in the east around the same time as the Sun is setting in the west, which means it will be visible all night long. This is great for finding your way around in the dark, but the Moon’s glare is generally not welcomed by stargazers as it makes fainter objects harder or impossible to see.

Still on the subject of the Moon, today at 12:54pm it will reach apogee (the opposite of perigee), which is the farthest point in its orbit around the Earth. The distance separating the centres of the two bodies will be 406,536 kilometres.

Jan 23

If you’re awake around midnight, look out to the east and you’ll see the Moon with a reddish star just below it. That ‘star’ is actually the planet Mars. Mars is a small planet, so you need at least a medium-sized backyard telescope to get any decent sort of view of it. But even as you gaze at it with the naked eye, stop and think for a moment – right now there are two missions on their way to Mars (NASA’s MAVEN and India’s Mars Orbiter), plus there are three orbiters and two operational rovers already working at or on the Red Planet. When the two new spacecraft reach their destination in September 2014, Mars is going to become a busy place!

Diagram of the evening sky for January 23

The Moon and Mars will be near each other in the sky in the early hours of January 23.

Jan 24

It is last quarter Moon today at 4:19pm. When you take a look tonight, you’ll notice that Moon has moved a bit since last night (as a result of its slow crawl around its orbit), and Mars is now above and to its left. But directly above the Moon is a bright star called Spica, which is the brightest star in the constellation Virgo. Spica is a blue giant star located about 260 light-years from Earth.

Jan 26

If you’re awake in the early hours after midnight, you’ll be rewarded with the view of the just-less-than-half Moon down near the eastern horizon, with a brightish ‘star’ just above it. That’s not a star, it’s the planet Saturn. If you have access to a small telescope, train it on Saturn and you’ll its magnificent system of rings.

Jan 29

If you’re up before the sunrise today, look out to the east and you’ll see a very thin crescent Moon. Just below it is what looks to be a very bright star, but is in fact the planet Venus. After the Sun and the Moon, Venus is the brightest object in the sky.

Diagram of the morning sky for January 29

The thin crescent Moon will be near Venus in the morning sky on January 29. (Venus is not shown to scale in this diagram.)

Jan 30

The Moon reaches perigee today, with the distance between the centres of the Earth and Moon being 357,079 kilometres.

Jan 31

New Moon occurs for the second time this month, at 8:39am

Here are some more great sources of southern stargazing information:

Melbourne Planetarium

Royal Astronomical Society of New Zealand

If you have any questions or comments on the night sky, we’d be happy to answer them. Please use the Feedback Form below. Happy stargazing!

Images courtesy IAU.

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