Astroblog

Morning sky as seen from Adelaide facing north-east at 4:00 am ACDST on 23 October, the Orionid radiant is indicated with a starburst. Similar views will be seen elsewhere in Australia at an equivalent local time. Click to embiggen.

The Orionids are a worthwhile shower that somewhat favours the Southern Hemisphere,best seen between 2-5 am, the radiant, the point where meteors appear to originate from, being just under Betelgueuse, the bright red star in Orion.

If you draw an imaginary line between Procyon and Aldebaran, then drop another imaginary line from Betelgeuse to the horizon, the radiant is just next to the intersection of those two lines.

The Orionids are the debris from Halley's comet. The Orionids maximum is on October 21 UT (October 22 Australian time).


This year the sky is nicely dark for the shower.

Despite the maximum being on the 22nd Australian time, the best viewing is the morning of the 23rd, when between 3-5 am under dark skies you should see about a meteor every 3-5 minutes.

You can find out the predicted rates for your location using the NASA meteor flux estimator (use 8 Orionids and make sure you set the dates to 22-23 October 2015).

If you decide to get up, allow at least 5 minutes for your eyes to adjust, and be patient, it may be several minutes before you are rewarded with you first meteor, then a couple will come along in quick succession.

Choose a viewing spot where you can see a large swathe of sky without trees or buildings getting in the way, or with street-lights getting in your eyes. The darker the spot the better (but do be sensible, don't choose a spot in an unsalubrious park for example). Look to the north-east, and the distinctive red star Betelgeuse below the saucepan will be easy to spot. The meteors should originate just below here. However, let your eyes roam a bit to pick up meteors that begin their "burn" a fair distance from the radiant.

A lawn chair or something similar will make your observing comfortable (or a picnic rug spread on the ground and a nice pillow), and having a Thermos of hot coffee, tea or chocolate to swig while watching will increase your comfort. (Here's some hints on dark adaption of your eyes so you can see meteors better).

Here is the near-real time satellite view of the clouds http://satview.bom.gov.au/
Cloud cover predictions can be found at SkippySky.   

Labels: Meteors, Observational Astronomy, unaided eye

The northern horizon at 4:00 am ACDST as seen from Southern Australia (northern Australia is similar but Gemini and the radiant is higher in the sky) on Monday December 15. The Geminid radiant is marked with a starburst (click to embiggen).


The Geminids are unusual in that their parent body is 3200 Phaethon, an asteroid, rather than a comet. It is speculated though that Phaeton is actually a "gassed out" comet, and so the debris that makes up the Geminids may still be cometary particles.
 
The Geminids are a fairly reliable meteor shower and although this year moonlight will interfere a bit, but some decent meteors should be seen. 

Unlike the Leonids, where there is a very narrow peak of high activity, the Geminids have a broad peak and will show good activity well before and after the peak, and on the day before and after.The peak is December 14, 12^h00^m UT. That is midnight December 15 in Australia.  However, the radiant doesn't rise until just before midnight (daylight saving time) in most of Australia, so you will still have to disturb your sleep for this one. 

Despite the peak occurring before radiant rise, and the influence of the last quarter Moon, Australians should see a meteor every three to four minutes under dark skies in the early morning of the 15th, between 2:00 am and 4:00 am local time. You can find predictions for your local site at the meteor flux estimator (choose 4 Geminids and date 14-15 December, don't forget to change the date to 2015).



At 1.00 am in the morning AEDST (midnight, AEST) Castor (alpha Geminorum) is about two hand-spans above the horizon and 10 hand-spans to the left of due north. Pollux, the other twin, is less than a hand-span to the left again. The radiant is just below Pollux.

When you get up, allow at least 5 minutes for your eyes to adjust and become dark adapted (even if you have stumbled out of bed in the dark, here's some hints on dark adaption of your eyes so you can see meteors better) and be patient, it may be several minutes before you are rewarded with you first meteor, then a couple will come along in quick succession (a meteor every three minutes is an average, they won't turn up like a ticking clock but more or less randomly).

Choose a viewing spot where you can see a large swathe of sky without trees or buildings getting in the way, or with street lights getting in your eyes. The darker the spot the better (but do be sensible, don't choose a spot in an insalubrious park for example). While the radiant is where the meteors appear to originate from, most of the meteors will be seen away from the radiant, so don't fixate on the radiant, but keep your eye on a broad swath of sky roughly centred just above the radiant (as the radiant doesn't rise very high, looking exactly at the radiant will mean you miss some higher up).

A lawn chair or something similar will make your observing comfortable (or a picnic rug spread on the ground and a nice pillow), and having a Thermos of hot coffee, tea or chocolate to swig while watching will increase your comfort. Despite it being summer, make sure you have a jumper or something as the night can still get cold

Guides to taking meteor photos are here and here.

As well, Orion and the Hyades will be visible and bright Jupiter will be nearby. So it will be a quite nice morning for sky watching. Keep an eye out for satellites!

Cloud cover predictions can be found at SkippySky. 

Labels: Meteors, Observational Astronomy, unaided eye

The evening sky facing east in Australia on April 9 at 21:00 AEST (9:00 pm AEST) showing the Mars, Spica, Saturn and Vesta and Ceres (click to embiggen) .

The Opposition of Mars is tonight (April 9). Mars is at its biggest and brightest tonight. After this the ruddy planet will be slowly growing smaller and dimmer but for the rest of the month and into May, it still repays close attention. This post will give you a brief guide to observing this fabled world. At least for those of us not clouded out by the tropical storm about to soak Queensland.

You don't need a telescope or complicated imaging equipment to observe Mars, although a telescope or binoculars helps. Before I describe observing Mars, a few words about the opposition.

This year is a fairly poor opposition of Mars. However, it is better than the 2010 and the really poor 2012 opposition, and we will have to wait until 2018 for a really good one. What is an opposition? Opposition refers to when a planet is opposite the Sun in the sky. This can only happen to outer planets, as Earth must pass between the Sun and the planet. The Earth passes Mars in its orbit every 26 months, and at this time we get a good view of the Red Planet.

When Mars is also making its closest approach to the Sun, our view is very good indeed. While Mars is on average 228 million km from the sun, due to Mars's elliptical orbit this varies by 42 million kilometers. If Mars is at its furthest from the Sun at opposition, Mars is also around 99 million km from Earth, while if Mars is at its closest to the Sun during opposition, this value narrows to only 57 million km. Favorable oppositions occur only once in every 15 to 17 years. During the Great Opposition of 2003, Mars and Earth were a mere 55.8 million km apart. This degree of closeness will not be achieved again until 2287. This year, Mars and Earth will be 92.4 million km apart.

Oppositions in the early months of the year, when Mars is furthest from the Sun, are always poor. The best oppositions occur around August. This is very good for Southern observers, as Mars is high in the sky, and the winter sky is usually still and transparent, ideal conditions for watching Mars. This years opposition occurs during April. The conditions are reasonable for Southern Observers. The weather is cooling, reducing  atmospheric turbulence and making Mars's disk more observable. The polar cap is currently easily visible. The visible disk of Mars is now 15.1 arc seconds (an arc second is approximately 1/3600th of your fingerwidth). While this sounds astoundingly small, 15.1 arc seconds will give a smallish but passable disk in most amateur telescopes, even the small ones from Tasco.

What you can expect to see:

Unaided eye. The best observing will be from April to May. Mars rises around sunset, so Mars is best observed from 10 pm - midnight standard time for most of this period. At 11 pm AEST Mars is the brightest object in the sky, its distinctive red colour making it easy to identify (Jupiter having set). In April Mars is in the northeast, and 8 handspans above the northeastern horizon as seen from Melbourne (when your hand is held out flat, thumb in, with your arm outstretched, your hand covers 6 degrees of sky, see diagram at right, people in Adelaide and Sydney should add an extra handspan, Brisbane and Alice Springs an extra two and from Darwin Mars is 6 handspans high). See the diagram at the beginning of the post to see what you should expect.

Mars is near the distinctive bright star Spica, the brightest star in Virgo, the constellation of the Virgin. Mars is also not far from Saturn and the asteroids Vesta and Ceres. Mars is magnitude -1.5, and is the brightest object in the late evening sky. Mars fades over the month to magnitude -1, making it the second brightest object in the sky after Sirius. By the end of May it is a still bright magnitude -0.3

Aside from just watching Mars every few nights you can do more detailed observation. Plotting the position of Mars every few nights (use a torch covered in red cellophane to stop your night vision being destroyed while you draw its position) will be interesting. In mid May Mars is stationary, and reverses direction during late May. This is called retrograde motion, and occurs due to Earth overtaking Mars in its orbit. Also, by comparing the brightness of Mars every couple of nights you can plot the fall in the brightness of Mars.

Mars as seen in 10x50 binoculars on April 9. It is not exciting.

Binoculars. Mars is not visible as a disk with 10 x 50 binoculars and larger this opposition. It is not near anything interesting until late June when it comes close to Spica.

Telescopes.The best time to observe Mars is when it is highest in the sky, unfortunately this occurs around midnight for a large proportion of best viewing times. Be prepared for some late nights if you want the best telescopic views.

Mars shows clearly visible markings in a 50 mm refractor telescope (if you have a 6 mm eyepiece), and significant detail can be seen in a 4" reflector, while 6" and 8" instruments will give better detail still. No current Earth-bound telescope can reveal the huge volcano, Mons Olympus, or the huge valley of Vale Marensus, which are seen in many of the spacecraft images. However, the polar caps will be seen clearly in even a small telescope. Significant features such as Syrtis major may be visible in 4" telescopes with good eyepieces under good observing conditions (see my webcam images from 2005). See the Google Mars Map for significant Mars features, or the JPL solar system simlulator to see what part of Mars is facing you when you are observing.

Mars as seen at this opposition through a 6" reflecting telescope with a 12 mm eyepiece. You will need a 6mm eyepiece to see the markings.

The Martian day is about 40 minutes longer than the Earth day, so if you observe at the same time each night, you can see the surface features rotating into and out of view. Dust storms can also occur, sometimes lasting days. Wind removal and deposition of the reddish, iron rich dust can also reveal or obscure features, so Mars's appearance can be somewhat different between each opposition.

Seasonal winds alternately covering and uncovering darker features with lighter dust were once interpreted as seasonal plant growth. Studying the Martian storms and the changing surface features is a valuable amateur activity.

So April to May is an excellent time to dust off that old telescope lying around in the garage, or to beg a view from a friend or neighbour with a telescope. Better yet, many astronomical clubs hold open nights, and this is an excellent opportunity to see this fascinating world in a decent telescope. Also, some of the local planetariums may be showing off Mars if they have telescopes.

For recording the appearance of Mars, all you need is a sheet of paper on a sturdy background, a pencil (or coloured pencils if you want to try recording the colors you see), a small torch covered in red cellophane and a watch. Make sure you and your telescope are located in a relatively dark place, and have modest circles predrawn on your paper (I use a 20 cent piece or my telescope eyepiece cap). Have your telescope out for a while beforehand so that it is at ambient temprature, to prevent air currents in the telescope from ruining the image. Record the date and time, and the weather (if it is windy, how much cloud, how much moonlight, what is the dimmest star you can see, etc.). Make sure you are wearing warm clothing, then make yourself comfortable at the eyepiece, preferably with a chair that allows you to sit and view comfortably, and, well, start drawing. It may take a few tries before you get the hang of recording what you see by red light, but you will feel a warm glow of accomplishment when you can.

Here are some links to Mars sites of interest:

Labels: Mars, Observational Astronomy, Opposition, unaided eye observation

Occultation of Saturn on May 14. Inset shows telescopic view.

What's up in 2014? There's lots of good stuff happening in the sky to look forward to, I've written an article about what we can expect (a partial solar eclipse, two total lunar eclipses, three occultations of Saturn and three comets) for ABC science online. You can read Your 2014 Aussie sky guide here.

Labels: eclipse, Observational Astronomy, Occultation, Saturn, science communicators

Eastern Sky at 8:30 pm daylight saving time.

At 8:30 pm on Saturday 31 March thousands of people will turn their lights and other electrical equipment off for Earth Hour. What can you do in the dark? Well, you know my answer to that … go out and look at the sky! If you have an old telescope lying about, or a pair of binoculars, go grab them and dust them off. Why not hold an Earth Hour Star Party?

For us urbanites and suburbanites the sky won’t get very dark during Earth Hour, because essential lighting will stay on. However the sky will still be great to see.

Over on the north-eastern horizon the brightest object is Mars, followed by Saturn, close to the bright white star Spica above the eastern horizon. You will need to wait a bit for Saturn to be higher in the sky before using a telescope on it.

The North-western sky at 8:30 pm local daylight saving time (click to embiggen)

To the West, Orion the Hunter and his belt (the saucepan to us Aussies, young men dancing to the Boorong people) can be seen clearly, below that is the V-shaped group of stars that make up the head of Taurus the Bull with the baleful red star Aldebaran as its eye. If you are lucky to have a clear, level horizon you can see the Pleiades Cluster twinkling above the horizon with bright Venus nearby.

To the South, you can see the pointers showing the way to the Southern Cross. Just below Mimosa, the second brightest star in the cross, the delightful Jewel Box cluster is visible in binoculars and telescopes. Above the Cross is the rambling constellation of Carina, the keel of the mythical ship Argos. There are lots of small beautiful clusters in the sky here. Sweeping around with binoculars will find many delightful groups of stars. You may even find the Tarantula Nebula!

The Southern sky at 8:30 pm local daylight saving time (click to embiggen)

Sadly, there are no passes of the International Space Station or Iridium flares during Earth Hour (although the ISS passes at 7:53 pm), but look carefully and you might see some dimmer satellites tumbling past, or maybe even a meteor!

In no time at all the lights will come on., and you will not have finished exploring the skies.

Labels: Earth Hour, Observational Astronomy

Eastern Sky at 8:30 pm daylight saving time.

At 8:30 pm on Saturday 26 March thousands of people will turn their lights and other electrical equipment off for Earth Hour. What can you do in the dark? Well, you know my answer to that … go out and look at the sky! If you have an old telescope lying about, or a pair of binoculars, go grab them and dust them off. Why not hold an Earth Hour Star Party?

For us urbanites and suburbanites the sky won’t get very dark during Earth Hour, because essential lighting will stay on. However the sky will still be great to see.

Over on the eastern horizon the brightest object is Saturn, close to the bright white star Spica. You will need to wait a bit for Saturn to be higher in the sky before using a telescope on it.

The North-western sky at 8:30 pm local daylight saving time (click to embiggen)

To the West, Orion the Hunter and his belt (the saucepan to us Aussies, young men dancing to the Boorong people) can be seen clearly, below that is the V-shaped group of stars that make up the head of Taurus the Bull with the baleful red star Aldebaran as its eye. If you are lucky to have a clear, level horizon you can see the Pleiades Cluster twinkling above the horizon.

To the South, you can see the pointers showing the way to the Southern Cross. Just below Mimosa, the second brightest star in the cross, the delightful Jewel Box cluster is visible in binoculars and telescopes. Above the Cross is the rambling constellation of Carina, the keel of the mythical ship Argos. There are lots of small beautiful clusters in the sky here. Sweeping around with binoculars will find many delightful groups of stars. You may even find the Tarantula Nebula!

The Southern sky at 8:30 pm local daylight saving time (click to embiggen)

Sadly, there are no passes of the International Space Station or Iridium flares during Earth Hour, but look carefully and you might see some dimmer satellites tumbling past, or maybe even a meteor!

In no time at all the lights will come on., and you will not have finished exploring the skies.

Labels: Earth Hour, Observational Astronomy

The evening sky facing north-west in Australia on Sunday May 16 2010 at 6:00 pm local time showing Venus and the Moon.

Venus has a rather lovely encounter with the thin crescent Moon this Sunday evening. Night of the "Smiley Fritz" it is not, but with the thin Crescent Moon just below Venus, the pair between the two brightish stars that make the horns of Taurus the Bull (Elnath and Zeta Tauri), and with Orion nearby, this should be very beautiful.

Start watching around half an hour after Sunset. Venus and the Moon will be obvious. As the twilight deepens, the other stars will slowly begin to emerge from the twilight glow, building up the display. Elsewhere in the world (Indonesia, South-East Asia, India, Northern Africa), Venus will be covered by the Moon.
EDIT: pictures now up here.

Labels: Moon, Observational Astronomy, unaided eye observation, Venus

I'm attending another Virtual Telescope experience, "Walking on the Moon". Part of Global Astronomy Month, Like the Messier Marathon and the Exoplanet Observation, this is pretty cool. Even after years of Astronomy, images of the Moon still are wonderful and enthralling.

Sadly, my experience was not optimal. As MiddleOne got a flight simulator program for his birthday, he's rigged up headphones to the computer for it. Headphones with a cord that reach his ears but not mine. So I now have tiny headphones on the desk, trying to listen to Gianluca narrate what's going on. Can't hear much. Anyway, here's some images from the session to enjoy.

As always, click on the image to embiggen (you won't be disappointed)

Labels: International Year of Astronomy, Observational Astronomy, telescope, virtual telescope

I've just had another Virtual Telescope experience, this one at a more reasonable hour. The Virtual Telescope had a world first, a live webcast of an exoplanet transiting its star. The exoplanet being TrES-3b. (click on any image to embiggen)


Located ( from our point of view anyway) in Hercules (see second image) TrES-3 is a world that is nearly twice the size of Jupiter orbiting its sun in just 31 hours (see first image for a Celestia simulation). It will probably crash into its sun in the "near" future.



The lefthand image shows TrES-3, the parent sun of TrES-3b in the CCD window of the virtual telescope (its the one to the left of the blue bar). The righthand image shows the growing light curve as the transit went on. It was pretty exciting to watch a real-time exoplanet transit, listening to Gianluca Masi's narration.
.

The lefthand image is the completed graph of the transit, showing the full dip of the stars light as the exoplanet passed in front of it, and the last image is my participation certificate.

Labels: astrophotography, International Year of Astronomy, Observational Astronomy, telescope

Western horizon half an hour after sunset on Saturday April 3.

Over the next few days Venus and Mercury will be close together. However, from the Southern Hemisphere, the pairing will be very close to the horizon at civil twilight (half an hour after local sunset, 6:30 pm here in Adelaide).

To see the pairing over Easter, you will need a flat, unobstructed horizon (like the ocean or the desert). Even then, Mercury will be low in the murk of the horizon, so you may need binoculars to pick it up down in the glow. Venus should be very easy to see though.

PS Southern Skywatch will be up tomorrow night, I spent the night helping MiddleOne paint his jet.

Labels: Mercury, Observational Astronomy, unaided eye observation, Venus

Northern Horizon on Saturday March 27 at 8:30 pm local daylight saving time in Australia (click to embiggen).

At 8:30 pm on Saturday 27 March thousands of people will turn their lights and other electrical equipment off for Earth Hour. What can you do in the dark? Well, you know my answer to that … go out and look at the sky! If you have an old telescope lying about, or a pair of binoculars, go grab them and dust them off. Why not hold an Earth Hour Star Party?

For us urbanites and suburbanites the sky won’t get particularly dark during Earth Hour, partly because essential lighting will stay on and partially because the Moon is nearly ¾’s full. However the sky will still be great to see.

To the north, the waxing moon is just above Regulus, the brightest star in Leo, the Lion (see above image). The Moon is always fantastic in binoculars or a telescope; indeed, you may spend all of Earth Hour moon gazing if you are not careful.

To the east of that the next brightest object is Saturn; you may need to wait a bit for Saturn to be higher in the sky before using a telescope on it. To the west is bright red Mars (sadly a small featureless disk in most small telescopes at the moment) and the stars Castor and Pollux of Gemini. Mars, Regulus and Saturn make a long line in the sky. The brightest star in the Sky, Sirius, and bright Procyon below it also form a long line with Mars.

The North-western sky at 8:30 pm local daylight saving time (click to embiggen)

To the West, Orion the Hunter and his belt (the saucepan to us Aussies, young men dancing to the Boorong people) can be seen clearly, below that is the V-shaped group of stars that make up the head of Taurus the Bull wit the baleful red star Aldebaran as its eye. If you are lucky to have a clear, level horizon you can see the Pleiades Cluster twinkling above the horizon.

To the South, you can see the pointers showing the way to the Southern Cross. Above the Cross is the rambling constellation of Carina, the keel of the mythical ship Argos. There are lots of small beautiful clusters in the sky here. With the Moon so bright, they will not be prominent, but sweeping around with binoculars will find many delightful groups of stars. You may even find the Tarantula Nebula!

The Southern sky at 8:30 pm local daylight saving time (click to embiggen)

Sadly, there are no passes of the International Space Station or Iridium flares during Earth Hour, but look carefully and you might see some dimmer satellites tumbling past, or maybe even a meteor!

In no time at all the lights will come on., and you will not have finished exploring the skies.

Labels: Earth Hour, Observational Astronomy, unaided eye observation

This blob is Mars. It's a blob because we are having lovely warm weather here in Adelaide (no point in clicking to embiggen, it doesn't get any better).

You would think that warm weather would be ideal for astronomy, as you don't have to dress up in multiple layers like the Michelin Man or run the risk of losing favourite extremities to frost bite. On the other hand, the warm air and ground means atmospheric turbulence, and to an astronomer, the atmosphere is the enemy.

Warm air rises from the warm ground, cooler air percolates down, and all this happens chaotically, rather than smoothly. These bubbles of warm and cold air act as lenses magnifying or reducing the image of the Moon or planet, unfortunately, they do it chaotically, and ever changeingly, so the image of the planet (and its focus) jiggles around like a diseased chicken (see the video of the Moon down below to see what I mean). Now, there are ways to get around this, using a video-type camera taking tens of frames in one exposure, you can use a program like registax to sift through the frames, eliminate the real stinkers and average out the rest to give an acceptable image.

But when things are really bad nothing will help. The bubbles twinkle faster than the shutter speed of your video camera (in my case a Phillips ToUCam web cam) and the image is hopelessly blurred beyond all the help of fast Fourier transforms or wavelet analysis. It is then that sketching comes in handy, your eye has better time resolution than any web cam, and you can catch the fleeting moments when the planet is in focus and set them down.

Mars changes in size over the month (click to embiggen).

Where in the sky the planet is matters as well. From Adelaide, Mars is barely 30 degrees (5 handspans) above the horizon. Mars is still close to all the murk that hangs around close to the horizon. And because of line of sight effects, the light from Mars has to travel through a whole lot more atmosphere (with a whole lot more chance to get bumped and bubbled around. That's why winter oppositions when the ecliptic is high in the sky and the air is cold and still, is the best for observing planets.



Twinkle, twinkle little star? It looks great in the sky, but if the stars near the planet you want to observe are twinkling furiously, forget getting the telescope out, the planet will be jiggling like demented jelly in your eyepieces.

Labels: Mars, Observational Astronomy

My Brother has sent me a link which people may find interesting and helpful. CreatioNova is a website that allows you to find out what is visible in the night sky. It is customisable for location, time of observation, limiting magnitude and objects you want to see, and returns Sunrise/Sunset, Moonrise/Moonset, planets, deep-sky objects and constellations. Deep-sky objects and Constellations come with links to explanatory information as hot links. Locations are all in right accession/declination and azimuth/altitude, so you need to have an idea of what these are, or a good skymap on hand. Give it a go.

Labels: Observational Astronomy

The North-east horizon as seen in Australia at 11 pm local daylight saving time (10:00 pm non-daylight saving time) showing the location of Vesta (click to embiggen) on the 10th of February.

While Mars is the focus at the moment, another opposition is upon us. That of the asteroid Vesta. Remember, an opposition is any time we are directly between an astronomical object and the Earth. Oppositions of Mars and Jupiter can be spectacular, but even humble chunks of rock can have oppositions. We generally don’t notice them, because they are invisible to the unaided eye.

One asteroid is an exception. At certain times the asteroid Vesta (hardly a humble chunk of rock, but the 4th largest asteroid) is visible to the unaided eye. Okay, so its magnitude 6, at the threshold of the eyes ability to see, and even in a strong amateur telescope, Vesta is a featureless dot. But still you are able to see a real asteroid, that was once counted as a planet, a left-over from the era of the formation of the Solar system.

This year, Vesta is not only visible (just, and then only if you are out at dark sky sites away from city lights), but it is relatively easy to find, being within a binocular field of the bright star Algieba (gamma Leonis) in the constellation of Leo. Algieba is the second brightest star in the distinctive, hook-shaped “sickle” of Leo which stars from the bright star Regulus. If you look to the north-east at around 11 pm local daylight saving time the sickle of Leo is clearly visible above the horizon to the right of distinctive red Mars (see Map above). Follow the sickle down from Regulus and you will find Algieba easily. Vesta will be off to the left of Algieba until the 16th, then it will be on the right. Vesta starts off on the 10th one and a half fingerwidths from Algieba, and gets closer every night until the 16th, when Vesta shoots between Algieba and the nearby 40 Leonis. There is only one other star as bright as Vesta within 2 fingerwidths radius of Algieba, and Vesta is obvious as it’s the one that moves from night to night.

Binocular Map showing the location of Vesta from 10-26 February, as seen through 10x50 binoculars (circle indicates field of view, click to embiggen) a printable PDF map is here.

Vesta will be at its brightest (and visible to the unaided eye) from 16-22 February, although it will be closest on 22 February (although it will take light 12 minutes to reach you from Vesta). While the challenge is to see Vesta with the unaided eye (again, you will need to be somewhere dark away from city lights to see Vesta without instruments), following Vesta in binoculars is very easy and highly rewarding.

You can test out your sketching skills by sketching the position of Vesta from night to night. The highlight of this opposition will be Vesta passing between Algieba and 40 Leonis on February 16th (update: see my observations here). This is best observed with binoculars or the low power eyepiece of a telescope (otherwise you won’t get both stars and Vesta in the field). Vesta moves fast enough that you can see it drift between the two bright stars.

Labels: 4 Vesta, asteroids, binocular, Observational Astronomy, Opposition, Vesta

Right: Sketch of Vesta near gamma Leonis on the 6th and 7th of February (Vesta indicated by a "v"), Left; Skymap Pro chart of same area.

While Mars is hogging the limelight at the moment, asteroid Vesta is heading for opposition later this month. As Vesta is near Gamma and 40 Leonis, finding it in binoculars is very easy (and Vesta will pass between gamma and 40 Leonis later in the Month too, a very interesting sight).

Since my webcam based imaging system isn't really up to faint stars, I've been sketching through binoculars. My sketches haven't turned out too badly, and the positions of stars and Vesta are pretty good considering I'm just holding my pad (size differences due to my binoculars having a smaller field of view). Some of the stars appear "double", but thats me just trying to darken up the dots, and missing the original in the dark. I can make out stars down to magnitude 9 through the binouclars on a bark night under suburban skies!

Anyone else sketching or imaging Vesta can send me their images if they like and I'll put them up here.

Labels: asteroids, Observational Astronomy, sketch, Vesta

My first Mars image of this opposition taken with Don the 8" reflector, my ToUCam and Vega. Roughly 40 images stacked with Registax.

Memo to self, when stars higher in the sky than Mars are twinkling, don't even bother. Couldn't even see the polar cap as I did when I was sketching last week.

Labels: astrophotography, Mars, Observational Astronomy, Opposition, webcam

The evening sky facing north-east in Australia on February 6 at 10:00 pm AEDST (9:00 pm AEST) showing the Mars and the Beehive Cluster (click to embiggen) .

Mars has been within a binocular field of the Beehive Cluster (M44, Praesepe) for most of this week, and will continue to be close for another week, however, between now and 7 February Mars will be closest to the Beehive.

The Beehive cluster is a beautiful , large, open cluster that is just visible to the unaided eye. Naturally it is much better under dark sky conditions. While you can see this with the uniaded eye, binoculars will give a better view. Through binoculars red Mars floats below a delicate scattering of jewels.

Mars as seen in 10x50 binoculars on February 6, near the Beehive Cluster (top).

Mars will be even closer to the Beehive in April, but not as bright.

Labels: binocular, cluster, Mars, Observational Astronomy, Opposition, unaided eye

The evening sky facing north-east in Australia on February 6 at 10:00 pm AEDST (9:00 pm AEST) showing the Mars and the Beehive Cluster (click to embiggen) .

The Opposition of Mars was on January 30th, 2010. Since then the ruddy planet has been slowly growing smaller and dimmer but for the rest of the month at least, it still repays close attention. This post will give you a brief guide to observing this fabled world. At least for those of us not clouded out by the ex-tropical storm soaking Queensland.

You don't need a telescope or complicated imaging equipment to observe Mars, although a telescope or binoculars helps. Before I describe observing Mars, a few words about the opposition.

This year is a fairly poor opposition of Mars. We will have to wait until 2014 to see better though, and we will have to wait until 2018 for a really good one. What is an opposition? Opposition refers to when a planet is opposite the Sun in the sky. This can only happen to outer planets, as Earth must pass between the Sun and the planet. The Earth passes Mars in its orbit every 26 months, and at this time we get a good view of the Red Planet.

When Mars is also making its closest approach to the Sun, our view is very good indeed. While Mars is on average 228 million km from the sun, due to Mars's elliptical orbit this varies by 42 million kilometers. If Mars is at its furthest from the Sun at opposition, Mars is also around 99 million km from Earth, while if Mars is at its closest to the Sun during opposition, this value narrows to only 57 million km. Favorable oppositions occur only once in every 15 to 17 years. During the Great Opposition of 2003, Mars and Earth were a mere 55.8 million km apart. This degree of closeness will not be achieved again until 2287. This year, Mars and Earth will be 99.3 million km apart.

Oppositions in the early months of the year, when Mars is furthest from the Sun, are always poor. The best oppositions occur around August. This is very good for Southern observers, as Mars is high in the sky, and the winter sky is usually still and transparent, ideal conditions for watching Mars. This years opposition occurs during January and February. The conditions are fairly poor for Southern Observers. The warm weather makes watching pleasant, but atmospheric turbulence is likely to be high, making Mars's markings harder to distinguish. However, the polar cap is currently easily visible. The visible disk of Mars is now 14 arc seconds (an arc second is approximately 1/3600th of your fingerwidth). While this sounds astoundingly small, 14 arc seconds will give a smallish but passable disk in most amateur telescopes, even the small ones from Tasco.

What you can expect to see:

Unaided eye. The best observing will be from February to mid March. Mars rises rather late, so Mars is best observed from midnight daylight saving time or 11 pm standard time for most of this period. At 11 pm AEDST Mars is the brightest object in the sky, its distinctive red colour making it easy to identify. In February Mars is in the northeast, and 4 handspans above the northeastern horizon as seen from Melbourne (when your hand is held out flat, thumb in, with your arm outstretched, your hand covers 6 degrees of sky, see diagram at right, people in Adelaide and Sydney should add an extra handspan, Brisbane and Alice Springs an extra two and from Darwin Mars is 6 handspans high). See the diagram at the begining of the post to see what you should expect.

Mars is between the distinctive pair of bright stars Castor and Pollux (the bright stars of Gemini, the twins) and bright Regulus in Leo. Mars is also not far from the beautiful open cluster, the Beehive cluster. On the 6th and 7th Mars is closest to the Beehive. Mars starts February at magnitude -1.3, and is the brightest object in the late evening sky. Mars fades over the month to magnitude -0.7, making it the second brightest object in the sky after Sirius.

Aside from just watching Mars every few nights (especially the nights it is close to the beehive if you are in a dark sky site) you can do more detailed observation. Plotting the position of Mars every few nights (use a torch covered in red cellophane to stop your night vision being destroyed while you draw its position) will be interesting. In late February Mars is stationary, and reverses direction during March. This is called retrograde motion, and occurs due to Earth overtaking Mars in its orbit. Also, by comparing the brightness of Mars every couple of nights you can plot the fall in the brightness of Mars.

Mars as seen in 10x50 binoculars on February 6, near the Beehive Cluster (top).

Binoculars. Mars is not visible as a disk with 10 x 50 binoculars and larger this opposition. However, watching Mars approaching the Beehive cluster (in February an later in April) is best done with binoculars - telescopes just can't get the Beehive into their field of view.

Telescopes.The best time to observe Mars is when it is highest in the sky, unfortunately this occurs well after midnight for a large proportion of best viewing times, and not long after midnight for the rest. Be prepared for some late nights if you want the best telescopic views.

Mars shows clearly visible markings in a 50 mm refractor telescope (if you have a 6 mm eyepiece), and significant detail can be seen in a 4" reflector, while 6" and 8" instruments will give better detail still. No current Earth-bound telescope can reveal the huge volcano, Mons Olympus, or the huge valley of Vale Marensus, which are seen in many of the spacecraft images. However, the polar caps will be seen clearly in even a small telescope. Significant features such as Syrtis major may be visible in 4" telescopes with good eyepieces under good observing conditions. See the Google Mars Map for significant Mars features, or the JPL solar system simlulator to see what part of Mars is facing you when you are observing.

Mars as seen at this opposition through a 6" reflecting telescope with a 12 mm eyepiece.

The Martian day is about 40 minutes longer than the Earth day, so if you observe at the same time each night, you can see the surface features rotating into and out of view. Dust storms can also occur, sometimes lasting days. Wind removal and deposition of the reddish, iron rich dust can also reveal or obscure features, so Mars's appearance can be somewhat different between each opposition. Seasonal winds alternately covering and uncovering darker features with lighter dust were once interpreted as seasonal plant growth. Studying the Martian storms and the changing surface features is a valuable amateur activity.

So February to mid March is an excellent time to dust off that old telescope lying around in the garage, or to beg a view from a friend or neighbour with a telescope. Better yet, many astronomical clubs hold open nights, and this is an excellent opportunity to see this fascinating world in a decent telescope. Also, some of the local planetariums may be showing off Mars if they have telescopes.

For recording the appearance of Mars, all you need is a sheet of paper on a sturdy background, a pencil (or coloured pencils if you want to try recording the colors you see), a small torch covered in red cellophane and a watch. Make sure you and your telescope are located in a relatively dark place, and have modest circles predrawn on your paper (I use a 20 cent piece or my telescope eyepiece cap). Have your telescope out for a while beforehand so that it is at ambient temprature, to prevent air currents in the telescope from ruining the image. Record the date and time, and the weather (if it is windy, how much cloud, how much moonlight, what is the dimmest star you can see, etc.). Make sure you are wearing warm clothing, then make yourself comfortable at the eyepiece, preferably with a chair that allows you to sit and view comfortably, and, well, start drawing. It may take a few tries before you get the hang of recording what you see by red light, but you will feel a warm glow of accomplishment when you can.

Here are some links to Mars sites of interest:

The Marswatch site, co-ordinating amateur observations of Mars.

Assoc of Lunar and Planetary observers has feature maps of Mars

The Mars newsletter of the ALPO

Solar system simulator, view Mars from Earth at any time.

Google Mars

The Nine Planets Tour, more info about Mars.

OnLine Astronomical Societies in Australia

Australian Planetariums (scroll down)

Mars Global Surveyor pages at NASA

The Mars Rovers, Spirit and Opportunity

Mars Express

Mars Reconnaissance Orbiter

Of course, no site would be complete without a link to the Face on Mars.

Labels: Mars, Observational Astronomy, Opposition, unaided eye observation

Left Image: Mars as sketched through my 4.5" Newtonian Reflector. Right Image: Mars earthward facing side at the same time as I was sketching, via the JPL Solar System Simulator.

The opposition of Mars for 2010 was last night. It was never going to be an auspicious opposition, Mars having the smallest diameter since 2003 and the opposition being in Summer here, Masr never gets far above the horizon, where murk and turbulence interfere with viewing.

Given that it was 36 degrees C during the day, and still 25 degrees in the middle of the night, turbulence was going to be a big problem. Also given that it was eldest sons bithday party (he is a prime number old, which is the sum of MiddleOnes age (an even number) and half SmalestOnes age (his full age is an even number and half is age is a prime)) with kids rushing around it was not going to be a good time to get out Don the 8" Newtonian and my astrophotography gear.

Still, I was able to get out my unguided 4.5" Netwonian and combine my youth watching duties with observing the red world. I even got the kids to have a look at Mars, the "Blue" Moon and Saturn.

Despite the viewing being shocking, through my 6.5 mm Plosell lens the bright white polar cap was clearly visible. There were also sufficient moments of stillness where I could see some darker markings, and I got them down. Satisyingly, despite the conditions my sketch is in good agreement with the surface marking that were visible at that time. Not bad, seeing as the smaller circle in my sketch is approximately the size Mars looked like through my 6.5 mm lens.

Mars will still be good for most of February, so why not get out and have a look?

Labels: Mars, Observational Astronomy, Opposition, sketch

Next time you are up in the morning looking at Saturn and Mars, let your eye wander over and down to Spica, the brightest star in the constellation Virgo. About halfway between that and the brightish star Gamma Hydri, is a dim, unprepossessing star; 61 Virginis (helpfully highlighted in the diagram opposite).

A mere 28 lightyears away, 61 Virginis is a Sun-like star that harbours at least three planets, discovered in a joint venture between the Keck Observatory and the Anglo-Australian Telescope (yes, Aussies had a hand in this) using radial velocity measurements . Measurement of minute Doppler shifts in the stars spectrum lead to the conclusion that the system has two Neptune like worlds, and one Super-Earth of 5 Earth masses, 61 Virb. The other reported 5x Earth Mass planet Gliese 581c, orbits a Red Dwarf star.

Although the star is Sun-like, and the planet is Earth-like (if a 5x Earth mass is sufficiently "Earth" like), the orbit is not. 61 Virb screams around its sun in 4.2 days, in an orbit well inside that of Mercury (not as close as WASP 18b though). The two Neptune mass planets 61 VirC and 61 VirD are also inside the orbits of Mercury and Venus, respectively, on elongated orbits. So this is a very "unsolar" solar system, unlike GJ 758b, which is a Jupiter-like planet in a solar system-like orbit around a Sun-like star.

The orbits of 61-Virginis b, c and d. B and c orbit closer than Mercury does to our sun (this and above image generated with Celestia).

You can read the original press release here. You can read the paper that will be published soon in The Astrophysical Journal here.

If you want to add the 61 Virginis system to Celestia, cut and paste the parameters below to a file and save it as 61Virb.ssc in the extras folder of Celestia.


=====================8<=cut===================================
"b" "HD 115617"

# 61Virb, vying for lowest mass exoplanet yet, with sunlike star


{
Texture "venuslike.*"
NightTexture "venuslike.*"

#Color [0 0.36 1]
#Albedo 0.05

Mass 5.1 # M.sin(i) = 5.1 Earths
Radius 12600

InfoURL "http://en.wikipedia.org/wiki/61_Virginis_b"

EllipticalOrbit {
Period 0.0115
SemiMajorAxis 0.05021
Eccentricity 0.12
Inclination 86
ArgOfPericenter 105
MeanAnomaly 166
}

Obliquity 82 # guess, to match inclination
#EquatorAscendingNode 96 # guess, to match ascending node

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "HD 115617/b"
{
Texture "extrasolar-lok.*"
}

"c" "HD 115617"

# 61Virc Neoptune like with sunlike star


{
Texture "exo-class2.*"

Color [0.98 0.97 1]
Albedo 0.75

Mass 18.2 # M.sin(i) = 18.2 Earths
Radius 49528

InfoURL "http://en.wikipedia.org/wiki/61_Virginis_b"

EllipticalOrbit {
Period 0.1041
SemiMajorAxis 0.2175
Eccentricity 0.14
Inclination 86
ArgOfPericenter 341
MeanAnomaly 177
}

Obliquity 82 # guess, to match inclination
#EquatorAscendingNode 96 # guess, to match ascending node

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "HD 115617/c"
{
Texture "extrasolar-lok.*"
}

"d" "HD 115617"

# 61Vird another Neptuneoid, with sunlike star


{
Texture "exo-class4.*"
NightTexture "exo-class4night.*"

Color [0 0.36 1]
Albedo 0.05

Mass 22.9 # M.sin(i) = 22.9 Earths
Radius 51118

InfoURL "http://en.wikipedia.org/wiki/61_Virginis_b"

EllipticalOrbit {
Period 0.3368
SemiMajorAxis 0.476
Eccentricity 0.35
Inclination 86
ArgOfPericenter 314
MeanAnomaly 56
}
=====================8<=cut===================================

Labels: exoplanet, extrasolar planet, Observational Astronomy, peer-reviewed research