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What’s up? Night sky for April 2012

Jonathan Nally — Thu, 29 Mar 2012 14:00:51 +0000

The southern sky is full of wonderful treats for the stargazer. (This star trail photo by Iztok Boncina was made by keeping the camera shutter open.)

Except where indicated, all of the phenomena described here can be seen with the unaided eye. And unless otherwise specified, dates and times are for the Australian Eastern Standard Time zone, and sky directions are from the point of view of an observer in the Southern Hemisphere. (If you’re in the Northern Hemisphere, please see the video at the bottom of the page for What’s Up in your night sky.)

April 3

The Moon, now just over three-quarters full, will be about 11 Moon widths above and to the left of the bright blue star, Regulus, the brightest star of the constellation Leo. A little further below is what looks like a red star, but is actually the planet Mars. The colours of Regulus and Mars make a nice contrast. About 77.5 light years from Earth, Regulus is not one star but four, grouped into two pairs. Multiple star systems are very common throughout the Milky Way galaxy.

April 4

The Moon is still in the vicinity of Mars tonight, being above and to the right of the planet. Incidentally, when I use a term such as “vicinity”, it is not to be taken as suggesting the two bodies are physically near each other out there in space. Rather, they are simply within similar lines-of-sight from our vantage point on Earth.

April 4, 8:00pm. The Moon, Mars and the star Regulus will make an attractive triangle in the northern part of the sky. Note the colour difference between blue Regulus and ruddy Mars.

April 7

Full Moon occurs today at 5:19am Sydney time (19:19 Universal Time on April 6). In a similar fashion to its “encounters” with Regulus and Mars a few days earlier, tonight the Moon will be about six Moon widths to the right of another bright star, Spica, and about 10 Moon widths above the planet Saturn. Spica is the brightest star of the constellation Virgo; it is a blue giant star about 260 light years from Earth. This is a great time to see Saturn (see April 16), so it’s a good idea to use the nearby Moon to identify it.

April 8

Today the Moon will be at the closest point in its orbit, called perigee. The distance between the two bodies today will be 358,311 kilometres.

April 10

This evening, take a look about 12 Moon widths below the Moon and you’ll see a reddish looking star that looks a bit like Mars. It’s the star Antares, and its name actually “rival of Mars”. Antares is the brightest star of the constellation Scorpius, and is a red supergiant star about 883 times bigger than our Sun!

Saturn, as it appears through a backyard telescope. Image by Steve Massey.

April 13

It is Last Quarter Moon tonight at 8:50pm Sydney time (10:10 Universal Time).

April 16

Today the planet Saturn reaches what astronomers call “opposition”. This means that, from an Earthly perspective, it is the opposite direction to the Sun—so if you could look down on the Solar System from above you’d see the Sun, Earth and Saturn (in that order) in a straight line … although Saturn, of course, is much further from us than the Sun. The period around opposition is a considered a great time to view a planet, as it rises in the east around the same time as the Sun sets in the west, and is therefore nice and high in the sky by late evening.

April 19

If you’re an early riser, out to east this morning before sunrise you’ll see the very thin crescent Moon. Above and to its right is a bright looking star. Well that’s not a star; it’s the planet Mercury, the closest planet to the Sun.

April 19, 6:30am. The thin crescent Moon and the planet Mercury will be visible together in the eastern sky before sunrise.

April 21

New Moon occurs today at 5:18pm Sydney time (07:18 Universal Time).

April 23

Today the Moon will again reach the farthest point in its orbit, apogee, at a distance from Earth of 406,421 kilometres.

April 24

Today the Moon makes another apparent close approach to a star, this time Aldebaran, the brightest star of the constellation Taurus. The pair will be low in the western sky after sunset. Like Antares, Aldebaran too is a red star, but not a supergiant—it is only about 44 times the size of our Sun. It’s about 65 light years from Earth.

April 25

There’ll be a lovely astronomical pairing in this evening’s sky, with the Moon very close to Venus. The Moon is the second-brightest object in our night sky, and Venus is the third-brightest.

April 25, about 7:15pm. The thin crescent Moon and Venus will be close together in the western sky.

April 29

It is First Quarter Moon today at 7:58pm Sydney time (09:58 Universal Time). First Quarter is a good time to look at the Moon through a telescope, as the sunlight angle means the craters and mountains are throwing nice shadows, making it easier to get that 3D effect.

There’s more great night sky viewing information at Melbourne Planetarium’s Skynotes site.

If you’re in the Northern Hemisphere, here’s a Jet Propulsion Laboratory video that details what you can see this month:

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 and Iztok Boncina / ESO.

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What’s up? Night sky for January 2012

Jonathan Nally — Sun, 01 Jan 2012 04:19:26 +0000

Summer nights are perfect for stargazing.

Except where indicated, all of the phenomena described here can be seen with the unaided eye. And unless otherwise specified, dates and times are for the Australian Eastern Daylight Time (AEDT) zone, and sky directions are from the point of view of an observer in the Southern Hemisphere.

January 1

It is First Quarter Moon today at 5:15pm AEDT. 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.

January 3

Today the Moon will reach the farthest point in its orbit from the Earth, which is called apogee. It’s distance from our planet will be 404,578 kilometres.

While you’re out looking at the Moon, you’ll notice a bright looking star above and to the left. Well, that’s not a star; it’s actually the planet Jupiter. If you have access to a telescope, or even a pair of 7×50 (or better) binoculars, train them on Jupiter and you should see up to four tiny pinpoints of light on either or both sides of the planet—these are the moons Galileo discovered, Io, Europa, Ganymede and Callisto. If you take a look again tomorrow night, you’ll see that their positions will have changed as they whiz around the planet.

And in fact, we’re only a few days away from the anniversary of their discovery. On the 7th of this month, it will be 402 years since Galileo spotted them!

January 5

Today the Earth reaches perihelion in its orbit around the Sun. Perihelion is the point in a solar orbit when the body in question (eg. Earth) is at its closest to the Sun. Perihelion occurs today at midday AEDT, at a distance between Earth and Sun of about 147,098,000 kilometres. (The opposite of perihelion is aphelion, which for Earth will occur on July 5, 2012 at a distance of about 152,098,000 kilometres.)

If you have a pair of binoculars, you’ll see a pretty sight tonight, with the soon-to-be-full Moon appearing to sit above a beautiful star cluster called the Pleiades, or Seven Sisters. When the Moon is not around and the sky is dark, most people can make out 6 to 7 of the Pleiades stars, although eagle-eyed stargazers can see a few more. There are actually hundreds of stars in this beautiful “open star cluster“, and it is also filled with beautiful whispy gas clouds, although the stars and the gas are not actually related to each other—we just happen to be seeing them at a time when the stars are drifting through the gas.

This is the view in the evening of January 5, with the Moon sitting above the beautiful star cluster known as the Pleiades. A pair of binoculars will show the scene well. Tomorrow night the Moon will have shifted east, and will be near to Albebaran, the brightest star in the constellation Taurus.

January 6

Tonight you might notice a fairly bright, reddish-looking star just above the Moon. This is Aldebaran, the brightest star in the constellation Taurus.

January 9

Full Moon occurs today at 6:30pm AEDT.

January 12

Tonight, the Moon will appear above and to the right of a bright blue star. This is Regulus, the brightest star in the constellation Leo.

January 14

In this morning’s pre-dawn sky out to the east, the Moon will appear above and to the left of the planet Mars, which looks like a ruddy-coloured star. As you gaze at it, spare a thought for the Mars Science Laboratory, which was launched a little under two months ago and which is due to reach the Red Planet on August the 6th this year.

January 16

It is Last Quarter Moon today at 8:08pm AEDT.

January 17

In this morning’s sky, the Moon will be just above and to the right of the planet Saturn, which looks like a bright star. Nearby is Spica, the brightest star in the constellation Virgo.

The Moon will be near to both the star Spica and the planet Saturn (the bright yellowish "star" below the Moon) on January 17. If you have access to a small telescope, take a look at both the craters and mountains on the Moon and Saturn and its glorious rings.

January 18

Today the Moon will be at the closest point in its orbit, called perigee. The distance between the two bodies today will be 369,887 kilometres.

January 20

In the early dawn sky, take a look for the Moon and you should see a reddish-looking star just above it. This is Antares, the brightest star in the constellation Scorpius. Compare Antares with Mars—do you think they look similar? The ancients thought so, and in fact the name Antares means “rival of Mars”.

January 23

New Moon occurs today at 8:39pm AEDT.

January 27

Tonight, there’ll be a lovely sight in the evening sky out to the west, with the crescent Moon paired with the bright planet Venus (about 20 Moon widths to its left).

January 30

This evening, the Moon meets up with Jupiter again, appearing below the planet in the northwestern part of the sky.

Also today, the Moon will again reach apogee again, at a distance from Earth of 404,323 kilometres.

The Moon will sit just below the planet Jupiter in the evening sky of January 30.

January 31

And finally for January, we have a second First Quarter Moon, which occurs today at 3:10pm AEDT.

There’s more great night sky viewing information at Melbourne Planetarium’s Skynotes site.

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!

Main image courtesy IAU.

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Australia’s newest telescopes – bird’s eye view

Jonathan Nally — Wed, 07 Dec 2011 13:01:52 +0000

The Australian Square Kilometre Array Pathfinder (artist's impression) is under construction in a remote part of Western Australia.

A NEW WEB FEATURE makes it possible to take a ‘bird’s eye view’ over the Murchison Radio-astronomy Observatory (MRO) and see the construction progress of CSIRO’s ASKAP radio telescope.

ASKAP Live is an interactive map of the 36 antennae that will make up the Australian Square Kilometre Array Pathfinder (ASKAP). In addition to showing the location of each antenna, ASKAP Live gives pictures and status reports on the construction of each antenna.

Colour coding provides, at a glance, the construction status of each antenna: antennae indicated by green icons have already been completed, those currently being constructed are in blue, and the six antennae that will make up the Boolardy Engineering Test Array, or BETA, are marked with yellow or purple icons.

A screenshot from the ASKAP Live web site.

All 36 ASKAP antennae are being constructed at the MRO by their manufacturer, the 54th Research Institute of China Electronics Technology Group Corporation (known as CETC54), with the assistance of CSIRO’s ASKAP team and local contractors.

The antennae are first built and tested in China by CETC54, with the antenna sections then disassembled and shipped to Australia. The antennae are then reassembled on site at the MRO, approximately 315 kilometres north east of Geraldton in the Mid West region of Western Australia.

Once built, ASKAP will operate as part of CSIRO’s radio astronomy facility for use by Australian and international scientists.

As well as being a world-leading telescope in its own right, ASKAP will be an important test-bed for the Square Kilometre Array (SKA), a future international radio telescope that will be the world’s largest and most sensitive.

Take a look at ASKAP Live.

You can also view the ASKAP Webcam.

Adapted from information issued by CSIRO.

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Kepler finds planet in the habitable zone

Jonathan Nally — Mon, 05 Dec 2011 21:37:21 +0000

This artist's conception illustrates Kepler-22b, a planet known to comfortably circle in the habitable zone of a Sun-like star. It is the first planet that NASA's Kepler mission has confirmed to orbit in a star's habitable zone—the region around a star where liquid water, a requirement for life on Earth, could persist. The planet is 2.4 times the size of Earth.

“Super Earth” found in its star’s “habitable zone”
Located 600 light-years away from our planet
Scientists studying 2,326 planet candidates

NASA’S KEPLER MISSION has confirmed its first planet in the “habitable zone,” the region around a star where liquid water could exist on a planet’s surface.

Kepler also has discovered more than 1,000 new planet candidates, nearly doubling its previously known count.

Ten of these candidates are near-Earth-size and orbit in the habitable zone of their host star. Candidates require follow-up observations to verify they are actual planets.

The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our Sun. The planet is about 2.4 times the radius of Earth.

Scientists don’t yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets.

Clear confirmation

Previous research hinted at the existence of near-Earth-size planets in habitable zones, but clear confirmation proved elusive.

Two other small planets orbiting stars smaller and cooler than our Sun recently were confirmed on the very edges of the habitable zone, with orbits more closely resembling those of Venus and Mars.

“This is a major milestone on the road to finding Earth’s twin,” said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington.

Artist's impression of the Kepler space telescope

“Kepler’s results continue to demonstrate the importance of NASA’s science missions, which aim to answer some of the biggest questions about our place in the universe.”

Kepler discovers planets and planet candidates by measuring dips in the brightness of more than 150,000 stars to search for planets that cross in front, or “transit,” the stars. Kepler requires at least three transits to verify a signal as a planet.

Follow-up with ground-based telescopes

“Fortune smiled upon us with the detection of this planet,” said William Borucki, Kepler principal investigator at NASA Ames Research Centre, who led the team that discovered Kepler-22b.

“The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season.”

The Kepler science team uses ground-based telescopes and NASA’s Spitzer Space Telescope to review observations on planet candidates the spacecraft finds.

The star field that Kepler observes in the constellations Cygnus and Lyra can only be seen from ground-based observatories in the Northern Hemisphere’s spring through early autumn.

The data from these other observations help determine which candidates can be validated as planets.

Over 1,000 new planet candidates

Kepler-22b is located 600 light-years away. While the planet is larger than Earth, its orbit of 290 days around a Sun-like star resembles that of our world. The planet’s host star belongs to the same class as our Sun, called G-type, although it is slightly smaller and cooler.

Of the 54 habitable zone planet candidates reported in February 2011, Kepler-22b is the first to be confirmed.

The Kepler team is hosting its inaugural science conference at Ames this week, announcing 1,094 new planet candidate discoveries.

This diagram compares our own Solar System to Kepler-22, a star system containing the first "habitable zone" planet discovered by NASA's Kepler mission. The habitable zone is the sweet spot around a star where temperatures are right for water to exist in its liquid form. Liquid water is essential for life on Earth.

Since the last catalogue was released in February, the number of planet candidates identified by Kepler has increased by 89 percent and now totals 2,326.

Of these, 207 are approximately Earth-size, 680 are super Earth-size, 1,181 are Neptune-size, 203 are Jupiter-size and 55 are larger than Jupiter.

The findings, based on observations conducted May 2009 to September 2010, show a dramatic increase in the numbers of smaller-size planet candidates.

Abundant Earths out there?

Kepler observed many large planets in small orbits early in its mission, which were reflected in the February data release.

Having had more time to observe three transits of planets with longer orbital periods, the new data suggest that planets one to four times the size of Earth may be abundant in the galaxy.

The number of Earth-size, and super Earth-size candidates, has increased by more than 200 and 140 percent since February, respectively.

There are 48 planet candidates in their star’s habitable zone.

While this is a decrease from the 54 reported in February, the Kepler team has applied a stricter definition of what constitutes a habitable zone in the new catalogue, to account for the warming effect of atmospheres, which would move the zone away from the star, out to longer orbital periods.

“The tremendous growth in the number of Earth-size candidates tells us that we’re honing in on the planets Kepler was designed to detect: those that are not only Earth-size, but also are potentially habitable,” said Natalie Batalha, Kepler deputy science team lead at San Jose State University.

“The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods.”

Adapted from information issued by NASA/Ames/JPL-Caltech.

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Australian dish charts where stars are born

Jonathan Nally — Thu, 01 Dec 2011 08:35:48 +0000

The Large Magellanic Cloud (LMC) is the nearest sizeable galaxy to our Milky Way, and is therefore a popular target for astronomers studying the evolution of stars.

ASTRONOMERS HAVE MAPPED in detail the star-forming regions of the nearest star-forming galaxy to our own, a step toward understanding the conditions surrounding star creation.

The researchers, led by University of Illinois astronomy professor Tony Wong—and including Associate Professor Sarah Maddison and PhD student Annie Hughes, both of the Swinburne University of Technology in Melbourne, Australia—have published their findings in the December issue of the Astrophysical Journal Supplement Series.

The Large Magellanic Cloud (LMC) is a popular galaxy among astronomers both for its nearness to our Milky Way and for the spectacular view it provides, a big-picture vista impossible to capture of our own galaxy.

“If you imagine a galaxy being a disc, the LMC is tilted almost face-on so we can look down on it, which gives us a very clear view of what’s going on inside,” Wong said.

CSIRO's 22-metre-diameter Mopra radio telescope, located near Coonabarabran in NSW.

As the LMC is in the far southern sky, it is an ideal target for Australian telescopes. And indeed, the team used the CSIRO’s 22-metre-diameter radio telescope at Mopra, near Coonabarabran in north-central New South Wales.

Where are stars born?

Although astronomers have a working theory of how individual stars form, they know very little about what triggers the process or the conditions in space that are optimal for star birth.

Wong’s team focused on areas called molecular clouds, which are dense patches of gas—primarily molecular hydrogen—where stars are born. By studying these clouds and their relationship to new stars in the galaxy, the team hoped to learn more about how gas clouds turn into stars.

Using the Mopra dish, the astronomers mapped more than 100 molecular clouds in the LMC and estimated their sizes and masses, identifying regions with ample material for making stars. This seemingly simple task engendered a surprising find.

Conventional wisdom states that most of the molecular gas in a galaxy is apportioned to a few large clouds. However, Wong’s team found many more low-mass clouds than they expected—so many, in fact, that a majority of the dense gas may be sprinkled across the galaxy in these small molecular clouds, rather than clumped together in a few large blobs.

False-colour image of the Large Magellanic Cloud galaxy combining maps of neutral atomic hydrogen gas (red), hydrogen energised by nearby young stars (blue), and new data from Wong’s team which roughly show the locations of dense clouds of molecular hydrogen (green). It's thought that stars form within molecular hydrogen clouds.

Star formation widespread in the LMC galaxy

The large numbers of these relatively low-mass clouds means that star-forming conditions in the LMC may be relatively widespread and easy to achieve.

To better understand the connection between molecular clouds and star formation, the team compared their molecular cloud maps to maps of infrared radiation, which reveal where young stars are heating cosmic dust.

“It turns out that there’s actually very nice correspondence between these young massive stars and molecular clouds,” Wong said.

“We can say with great confidence that these clouds are where the stars form, but we are still trying to figure out why they have the properties they do,” he added.

Adapted from information issued by University of Illinois at Urbana-Champaign. Mopra photo courtesy CSIRO. MAGMA image of LMC courtesy Tony Wong, University of Illinois.

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What’s up? The night sky for December 2011

Jonathan Nally — Wed, 30 Nov 2011 01:00:52 +0000

Stargazing is great fun, now that the warmer summer weather is here.

December 2

It is First Quarter Moon today at 8:52pm Australian Eastern Daylight Time (AEDT). 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.

December 6

Today the Moon will reach the farthest point in its orbit, apogee, at a distance from Earth of 405,412 kilometres. And if you take a look at the Moon this evening, you’ll see a bright ‘star’ above and to its right. That’s not a star—it’s actually the planet Jupiter!

December 9

Take a look at the Moon in this evening’s sky, and you’ll see a brightish star a little way out to its right. And yes, this one really is a star. It’s called Aldebaran, and it’s the brightest star in the constellation Taurus. Aldebaran is a red giant star roughly 44 times as big as the Sun, and is about 65 light-years from Earth.

December 10

Full Moon occurs today at 1:36am AEDT, and tonight everyone in Australia and New Zealand will experience a total lunar eclipse. See our separate lunar eclipse story for full details on how, when and where to see it.

Eclipses aside…although it looks very pretty high up there in the sky, astronomers, both amateur and professional, generally hate the full Moon. This is because its light tends to drown out many of the fainter objects they’re interested in seeing. (It does this by actually making the sky glow.) It’s also not a good time to look at the Moon itself through a telescope, as the overhead sunlight (as seen from the perspective of the Moon) doesn’t throw any shadows across the lunar surface—and shadows are what give the craters and mountains their 3D look.

The Moon looks great through a telescope, but you won't need one to see the total lunar eclipse on December 10, 2011.

December 17

If you’re up early today, look for the Moon and you’ll see that it seems to have two companions. A little way below and to its left is the star Regulus, and below and to its right is the planet Mars. Regulus is actually a quadruple star system, comprised of four stars in two groups of two, gravitationally bound to one another. But the main star is a young, blue star a little over three times the mass of the Sun, and about three to four times as big as the Sun too.

December 18

It is Last Quarter Moon today at 11:48am AEDT. The Moon is still near Mars in the sky, being above and to the right of the planet in the hours before dawn.

December 21

The Moon, a star and a planet make a nice triangle in this morning’s sky. The star is Spica, the brightest star in the constellation Virgo, and the planet is Saturn. Saturn will be to the left of the Moon, and Spica will be above Saturn. Spica, a blue giant star, is the 15th brightest star in the night sky and is about 260 light-years from Earth.

December 22

There are two items of note for today. First, the Moon will be at the closest point in its orbit, called perigee, which is the opposite of apogee. The distance between the two bodies today will be 364,800 kilometres. And secondly, today marks the summer solstice in the Southern Hemisphere. This is the day of the year when the Sun is highest in the sky.

December 25

New Moon occurs today at 5:06am AEDT.

December 27-28

The Moon is back in the western evening sky. Over these two nights, it’ll be paired up with the planet Venus—the duo will make a very attractive sight in the evening dusk.

There’s more great night sky viewing information at Melbourne Planetarium’s Skynotes site.

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!

Story by Jonathan Nally. Images courtesy IAU.

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ET’s nightlife could be a giveaway

Jonathan Nally — Mon, 07 Nov 2011 14:01:35 +0000

If an alien civilisation builds brightly-lit cities, like those shown in this artist's conception, future generations of telescopes might allow us to detect them. This would offer a new method of searching for extraterrestrial intelligence elsewhere in our Galaxy.

IN THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE, astronomers have hunted for radio signals and ultra-short laser pulses. But in a new proposal, Avi Loeb (Harvard-Smithsonian Centre for Astrophysics) and Edwin Turner (Princeton University) suggest a new technique for finding aliens—look for their city lights.

“Looking for alien cities would be a long shot, but wouldn’t require extra resources. And if we succeed, it would change our perception of our place in the universe,” said Loeb.

As with other SETI methods, they rely on the assumption that aliens would use Earth-like technologies. This is reasonable because any intelligent life that evolved in the light from its nearest star is likely to have artificial illumination that switches on during the hours of darkness.

Telling night from day

How easy would it be to spot a city on a distant planet? Clearly, this light will have to be distinguished from the glare from the parent star. Loeb and Turner suggest looking at the change in light from an exoplanet as it moves around its star.

As the planet orbits, it goes through phases similar to those of the Moon. When it’s in a dark phase, more artificial light from the night side would be visible from Earth than reflected light from the dayside. So the total flux from a planet with city lightingwill vary in a way that is measurably different from a planet that has no artificial lights.

Current technology could spot city lights on Pluto (artist's impression).

Spotting this tiny signal would require future generations of telescopes. However, the technique could be tested closer to home, using bodies at the edge of our Solar System.

Closer to home?

Loeb and Turner calculate that today’s best telescopes ought to be able to see the light generated by a Tokyo-sized metropolis at the distance of the Kuiper Belt—the region occupied by Pluto, Eris, and thousands of smaller icy bodies. So if there are any cities out there, we ought to be able to see them now.

By looking, astronomers can hone the technique and be ready to apply it when the first Earth-sized worlds are found around distant stars in our galaxy.

“It’s very unlikely that there are alien cities on the edge of our Solar System, but the principle of science is to find a method to check,” Turner said. “Before Galileo, it was conventional wisdom that heavier objects fall faster than light objects, but he tested the belief and found they actually fall at the same rate.”

As our technology has moved from radio and TV broadcasts to cable and fibre optics, we have become less detectable to aliens. If the same is true of extraterrestrial civilisations, then artificial lights might be the best way to spot them from afar.

Adapted from information issued by Harvard-Smithsonian Centre for Astrophysics. Images by David A. Aguilar (CfA) and ESO.

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What’s up? Night sky for November 2011

Jonathan Nally — Sun, 06 Nov 2011 00:48:08 +0000

Late spring nights and mornings are ideal for stargazing, and there are some interesting things to see this month.

November 3

It is First Quarter Moon today at 3:38am Australian Eastern Daylight Time. First Quarter is a good time to look at the Moon through a telescope, as the sunlight angle means the craters and mountains are throwing nice shadows, making it easier to get that 3D effect.

November 9

Take a look in the evening sky and you’ll see the Moon with what looks like a bright star above and to its right. Well, that’s not a star, it’s the planet Jupiter. Also today, the Moon will reach the farthest point from Earth in its orbit, apogee, at a distance from Earth of 406,176 kilometres.

November 10

Take a look at the western horizon after sunset and you’ll see a pretty group comprising Venus, Mercury and the star Antares.

The Moon teams up with several planets during November

November 11

Full Moon occurs today at 7:16am Australian Eastern Daylight Time.

November 11-12

Out to the east in the early morning sky (pre-dawn) you’ll find a pair of celestial orbs that contrast each other nicely in colour. Ruddy coloured Mars will appear very close to Regulus, a blue giant star that is the brightest star in the constellation Leo.

November 19

It is Last Quarter Moon today at 2:09am Australian Eastern Daylight Time. If you’re up before dawn, take a look out to the eastern sky and you’ll see the Moon with the star Regulus close by, and the planet Mars about 4 degrees away as well.

November 23

Another attractive grouping, but quite low in the eastern sky before dawn (so you’ll need a clear horizon). There’ll be the Moon, plus the star Spica (the brightest star in the constellation Virgo) and the planet Saturn as well.

November 24

Today the Moon will be at the closest point to Earth in its orbit, called perigee, which is the opposite of apogee. The distance between the two bodies today will be 359,691 kilometres.

November 25

New Moon occurs today at 5:10pm Australian Eastern Daylight Time.

November 27

Take a look out to the west just after sunset, and you might see the very thin crescent Moon below and to the right of the planet Venus.

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 / TWAN / Babak /A. Tafreshi.

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What’s up? Night sky for August 2011

Jonathan Nally — Mon, 01 Aug 2011 09:00:03 +0000

This month, Saturn will be the planet to watch in the western part of the sky after sunset.

FOUR PLANETS ARE VISIBLE THIS MONTH, although you’ll have to be quick to spot Mercury, as it starts the month low on the western horizon after sunset and within about a week will have become lost in the Sun’s glare.

Slightly higher in the western sky after sunset is Saturn, shining brightly and visited by the Moon on the 4th.

Jupiter and Mars are still the luminaries of the morning sky—Jupiter high in the north, and Mars low in the north-east. Their brighter sibling, Venus, will not be visible this month, as it is on the opposite side of the Sun from us.

August 1

Look for the very thin crescent Moon low in the west after sunset. The planet Mercury will be about seven Moon widths above and to the right. Mercury is becoming much harder to see now, and over the next week will sink lower and lower toward the horizon and become lost in the Sun’s glare. The innermost planet will reappear in our morning sky out to the east next month.

August 3

Today the Moon will be at the closest point to Earth in its orbit, called perigee, at 7:00am. The distance between the two bodies will be 365,755 kilometres.

August 4

Look for the Moon and Saturn close together in the west in the early evening sky.

August 5

The Moon and the star Spica—the brightest star in the constellation Virgo—will appear close together tonight. The Moon will be about six Moon widths above the star.

August 6

It is First Quarter Moon today at 9:08pm. 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.

August 8

Now almost three-quarters full, the Moon will be near the star Antares—the brightest star in the constellation Scorpius. Antares has a reddish colour, and to the naked eye it looks a bit like the planet Mars. In fact, its name means ‘rival of Mars’.

Make the most of the late-winter nights by doing some stargazing.

August 14

Full Moon will occur today at 4:58am.

August 16

If you’ve been wondering why Venus doesn’t appear to be in our evening or morning skies, it’s because it is lost in the glare of the Sun. Today marks its ‘superior conjunction’, which means that it is on the exact opposite side of the Sun from us.

August 17

Mercury, which has been lost in the glare of the setting Sun for a while now, today reaches ‘inferior conjunction’, which means that it is exactly between us and the Sun. Mercury will reappear low in the east in the morning sky next month.

August 19

Today the Moon will be at the farthest point from Earth in its orbit, called apogee, at 2:24am. The distance between the two bodies will be 405,159 kilometres.

August 21

Look out to the east this morning, and you’ll see the Moon and what looks like a very bright star above and to its left. That’s not a star; it’s the planet Jupiter. Even if you don’t have a telescope, a normal pair of binoculars should reveal up to four of Jupiter’s largest moons, looking like small pinpricks of light to one or both sides of the planets.

August 22

It is Last Quarter Moon today at 9:55pm.

August 26

If you’re an early riser, take a look out to the east and you’ll see the Moon very close to the planet Mars.

August 29

New Moon occurs today at 1:04pm.

August 31

Today the Moon will again be at the closest point to Earth in its orbit, perigee, this time at 3:36am. The distance between the two bodies will be 360,857 kilometres.

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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What’s up? Night sky for July 2011

Jonathan Nally — Wed, 29 Jun 2011 14:01:34 +0000

Stargazing during winter is chilly, but the nights can often be crisp and clear. And there's plenty to see this month!

THE INNERMOST PLANET, Mercury, has delighted us in the morning sky for the past couple of months, but this month it makes a reappearance in our evening skies, in the west after sunset. It’ll be quite easy to see, above the horizon for around 100 minutes after the Sun sets at the beginning of the month, increasing to almost two-and-a-half hours after the Sun sets by the end of the month.

Also in the evening sky, to the north-west, is Saturn. The famous ringed planet will be on show during the first half of the night, setting around 11:00pm by the end of the month.

In the morning sky to the east, Jupiter and Mars are still putting on a show before sunrise.

Venus is too close to the Sun to be seen this month.

July 1

There will be a partial eclipse of the Sun today, but you’ll have to be an albatross or maybe a seal in order to see it. That’s because the Sun’s shadow will fall across a remote area of ocean between South Africa and Antarctica. Unless there are some fishing boats or a scientific expedition in the area, it’s entirely possible that no one will witness this eclipse which, at its maximum, will see less than 10% of the Sun’s disc covered by the Moon. And speaking of the Moon, New Moon occurs today at 6:54pm Sydney time (08:54 Universal Time).

July 3, 2011, 5:15pm: The thin crescent Moon will sit just above the planet Mercury in the western sky after sunset.

July 3

Take a look out to the west after sunset, and you should see the planet Mercury above the horizon, and above it will be the thin crescent Moon.

July 5

Earth reaches aphelion today (or July 4 in the western hemisphere), which is the farthest point from the Sun in our orbit. The distance between Earth and Sun will be 152.1 million kilometres.

There’ll be an interesting sight out to the east in the morning sky today. The planet Mars will appear close to the star Aldebaran. Both are of similar brightness, and both have similar colouring—a sort of orangey-red.

In this evening’s sky, the Moon will sit above the bright star Regulus. Regulus is the brightest star in the constellation Leo. The amazing thing about Regulus is that, although to the naked eye it appears to be one star, in reality it is composed of four stars grouped into two pairs, all gravitationally bound to each other! This sort of thing is not too uncommon—many other stars are members of double, triple or quadruple systems too.

July 8, 2011, 7:15pm: The Moon will be bracketed by the planet Saturn and the star Spica, in the north-western sky.

July 8

It is First Quarter Moon today at 4:29pm Sydney time (06:29 Universal Time). 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. Also today, the Moon will be at the closest point to Earth in its orbit, called perigee, at 12:05am (14:05 on July 7, Universal Time). The distance between the two bodies will be 369,565 kilometres. And finally, tonight the Moon will appear reasonably near the planet Saturn.

July 9

A little more than half full, the Moon will appear quite close to the star Spica tonight. Spica, a blue giant star, is the brightest star in the constellation Virgo and the 15th-brightest star in our night sky.

July 12, 2011, 8:00pm: High in the northern sky, the Moon and the star Antares (the brightest star in the constellation Scorpius) will appear close together.

July 12

The now almost-full Moon will appear quite close to the star Antares tonight. Antares means “the rival of Mars’, and it’s not hard to see why, as it’s ruddy colour makes it look just like the fourth planet from the Sun. Antares is a red supergiant star, 800 times bigger than the Sun!

Today, the eighth planet from the Sun, Neptune, has completed one full orbit of the Sun since its discovery in 1846. Neptune takes almost 165 years to complete one circuit of the Sun. Neptune is too faint to be seen with the naked eye, but it is within the range of medium-and-larger backyard telescopes, if you know exactly where to look. This chart, provided by the Royal Astronomical Society of New Zealand, will help you to find it.

July 15

Full Moon occurs today at 4:40pm Sydney time (06:40 Universal Time).

July 20

Mercury reaches its greatest angle from the Sun today, so if you have a clear evening sky, why not take the opportunity to go out and spot it in the west after sunset?

July 20, 2011, 5:20pm: Mercury will be at its greatest angle from the Sun today, and visible in the west after sunset.

July 22

Today the Moon will reach the farthest point in its orbit around the Earth, called apogee, at a distance of 404,356 kilometres at 8:48am Sydney time (22:48 on July 21, Universal Time).

July 23

It is Last Quarter Moon today at 3:02pm Sydney time (05:02 Universal Time).

July 24

Slightly less than half full, the Moon will appear close to the planet Jupiter in this morning’s sky. Jupiter will be about 12 Moon widths above the Moon. Look a little further east and you’ll see Mars too. In between will be the beautiful star cluster called the Pleiades, also known as the Seven Sisters. Use binoculars or a small telescope and you’ll be delighted with the view.

July 24, 2011, 6:20am: The Moon and two planets—Jupiter and Mars—will be visible in the north-eastern sky before sunrise. See if you can spot the Pleiades star cluster as well.

July 25-28

In the western sky after sunset, the planet Mercury will appear close to the star Regulus (see July 5 for more information on this star).

July 28

The crescent Moon will appear very close to the planet Mars in this morning’s sky. They’ll be separated by only three Moon widths.

July 31

New Moon occurs today at 4:40am Sydney time (18:40 on July 30, Universal Time).

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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