Category Archives: Comets

The skies over Kendal in October

We’re moving into the darker, colder and usually rather cloudy nights of the end of the year. As ever, this post is illustrated with a few sky charts showing midnight on the first, last and fifteenth day of the month. The dots represent brighter stars, green circles are star clusters, nebulae, galaxies and the like and the very brightest stars, the Moon and the planets are named when they appear. Sky charts provided using Stellarium.

Solar system

The Moon will be in the last quarter phase on the 1st, new on the 7th, first quarter on the 14th and full on the 23rd. On the 14th, the Moon will occult the star 50 Sagittarii at around 8:10pm for northern observers.

The middle of the month sees the start of the Orionid meteor shower, which will peak on the 21st. Peak rates are low and a full Moon will blot out all but the brightest. Orionids are fast and leave persistent trails. They are best seen before dawn.

Heavens above presently lists two comets above magnitude 12 and seven asteroids above magnitude 10 in the hours of darkness. The comets are: 103P Hartley at 5.6 – approaching visibility – in Cassiopeia and 10P Tempel 2 at 10.1 in Cetus. Details on the future movements and changing brightness of the comets can be found here. The asteroids are 6 Hebe at 7.8 in Cetus; 4 Vesta at 7.9 in Virgo; 8 Flora at 8.6 in Aquarius; 1 Ceres at 8.9 in Sagittarius; 7 Iris at 9.4 in Gemini; 39 Laetitia at 9.5 in Aquarius and 471 Papagena at 9.8 in Cetus – rather a busy constellation this month.

The Planets

Mars is usually lost in atmospheric haze now. It shines at +1.5, appearing in the south-west, only to set an hour after the Sun.

Venus is seen just below Mars as the Sun sets, shining much brighter, but also lower, requiring a very low horizon to the West to see it.

Mercury for the next day or two, Mercury is visible in the Eastern horizon shortly before the Sun rises, though it will appear dimmer than its +1.3 magnitude suggests due to the bright sky around it.

Saturn returns to the skies at the end of the month, making an appearance shortly before dawn with rings now angled such that they look more like rings. The planet will shine at a magnitude of 0.7.

Jupiter continues to shine brightly as ‘that star in the East’. It shines at a magnitude of -2.9 and is in an empty part of the sky. Its inclination is such that transits of satellites happen quite a bit. Times of some of these and appearances of the Great Red Spot are here.

Uranus lies a couple of degrees west of Jupiter, plus a little above, and shines at 5.7.

Neptune is also in the morning skies, on the border of Capricorn and Aquarius.

A few things outside the solar system

The constellations of Leo, Virgo and the Big Dipper are all home to galaxies, details here. This is not a good month to look at faint things as the all-night twilight obliterates detail and contrast.

The Usual Stuff

If you want to watch satellites flaring or passing in the sky (even sometimes during the day), then go to Heavens Above to get times and directions. If you need assistance in deciding where things are in the sky, why not install the free program Stellarium, which does all the work for you? Finally, to avoid the dreaded clouds, Met Check gives a quick forecast and the Met satellites or other satellites can be used to track breaks in the cloud. For an indication of auroral or solar activity, is an invaluable resource. If the stars aren’t available, there’s always solar astronomy. Projections of the Sun onto white card can show sunspots, when properly focused. A good filter (not an eyepiece filter) or a dedicated solar telescope will show better details. Never observe the Sun without filters and never with an inadequate, inappropriate or old (and therefore possibly with holes in) filter.

Public events

For young astronomers (ages 9-16) Space Explorers is run in Kendal Museum on the third Saturday of most months from 2:30-4:00 pm. The next meeting is on Saturday the 23rd. The Society for Popular Astronomy also has a sky map for young astronomers here.

Plus why not pop along to the Eddington Society, which meets at Kendal Museum on the first Monday of each month, this month it is on the 4th, with member’s projects the subject of the meeting. There will also be a public observing event at The Brewery Arts Centre on the 15th from 6:30pm.

Don’t forget to check back here and on my twitter account for the latest astronomical events in this area.

Pan-STARRS spots hazard in space

The Panoramic Survey Telescope and Rapid Response System, or Pan-STARRS 1, is a 1.8 metre telescope with a 1.4 gigapixel camera mounted on it, constantly surveying the sky. It hunts stars, galaxies and also anything that moves from moment to moment, specifically comets, trans-Neptunian objects and asteroids. Now it has managed to capture an asteroid that may or may not pose a future hazard.

2010 STS3 is a 45 metre wide asteroid, capable of causing regional disruption on a par with the object believed responsible for the Tunguska explosion, which flattened trees after a similar sized object exploded in the atmosphere above the sparsely inhabited region.

The object poses no immediate risk, but as it is passing close to us, it will be monitored and its orbital parameter derived from dedicated follow up observations to help determine more precisely where it will be. Presently, there is a small chance of an impact in 2098, but the margin of error on the orbital parameters is too high to make any warnings relevant.

The main significance of 2010 ST3 was that Pan-STARRS saw it first, proving its ability to detect these things when they appear. Pan-STARRS 1 is set to be supplemented by Pan-STARRS 4, a larger, more sensitive observatory, which will assist in surveying the skies.

Icy happenings out there

An animation of Comet Hartley 2 (which can be found via this chart) has been doing the rounds. No idea of attribution, although it’s on a website hosted by Patrick Wiggins, but this shows the comet travelling through the skies (not yet visible to the naked eye):

Meanwhile the photograph below was taken by Will Gater:

Cassini, not to be left out, has also been taking snaps of watery happenings in space, with this image of Saturn’s satellite Enceladus leaking from its geysers.

Some observing alerts

Jupiter remains king in the sky at the moment, as Will Gater’s image, showing a transit of Io shortly after my own observations of it, illustrates:

That black dot is the shadow of the satellite, a vast area of eclipse moving over the cloudtops of that giant planet.

The two most distant major planets of the solar system are also available to be found at the moment.

We also have a comet in Cassiopeia, comet Hartley, now edging onto the visible end of the brightness range. Finder chart here.

And for more advanced observers, there’s a faint blue star in Auriga presently up in brightness by about five orders of magnitude (taking it to around 16). Further details and a finder’s chart are here.

Finally, slightly more advance warning has come in about how the proper motion of the stars will alter the appearance of constellations over the next 50,000 years (yes, they can write this knowing no-one’s going to take it up with them if they get it wrong).

Quick Observing report

The cold air tonight reminded me that there actually sometimes is a starry sky above my head. Seeing the clear, star pricked night, I assembled the Celestron 130SLT and eyepieces and quickly set it up outside. Not quick enough as a band of fast moving cloud headed between me and the targets. Defeated, I returned inside.

Not too long afterward, I returned and set up under a clearer sky with slower clouds. I took with me the Greenkat spotting scope as well. My three intended targets for the night were Jupiter, Uranus and the Comet 103P Hartley, which is breaching the magnitude 6.5 according to Heavens Above (finder chart here). My intention was to direct the main telescope straight onto Jupiter and Uranus and use the spotting scope’s wider field of view to scan for the comet before zooming in on it later, as I have done with previous ones.

This didn’t go quite to plan as a combination of the strong light of the Moon and neighbours popping by for a look meant the comet hunt was eventually called off. Although I did get a glimpse of Hartley, it didn’t seem quite good enough for a swing round of the Celestron.

Instead I concentrated on the brighter objects, taking in the turquoise Uranus before showing off Jupiter and the four Galilean moons to four neighbours. Three of the satellites were arranged in a similar way to the handle of the plough, all on one side of the planet. The fourth, Io, sat just off the limb, easily resolvable in the 9mm and 4mm eyepieces, but too close for the 24mm one to pick out. Just passed opposition, the giant planet is enormous in the eyepiece. As well as the remaining equatorial band, detail could be seen of the zones and caps, which is quite unusual for me to spot.

After this, a neighbour wanted to look at the just passed full Moon, so we swung onto that, with views of shadowed craters on the limb to see. With that done and the cold biting into everyone, the session was wrapped up and we headed back into our houses.

Dance of the planets in the dust

Spotting exoplanets is very hard to do directly. The best bet is to find an indirect method, such as the amount of light they block from their host star, the gravitational lens they produce as they pass between us and another object, or the amount they pull their host star about. Another suggestion is to look for how they alter the distribution of debris in their version of the solar system. Round these parts, the outer debris ring is the Kuiper Edgeworth belt, and just like Saturn’s rings are shepherded by Saturn’s moons, so this belt is kept in line by the planet Neptune. Looking for well kept borders enables some idea that a planet may be available, but when looking at even earlier times in a solar system’s formation, the evidence of an outer planet’s influence can be even easier to spot.

NASA researchers have now modelled the effect of Neptune on the belt, going back to the earliest times in the solar system’s history. They find a well kept belt forms in around 15 million years. The researchers plan to extend their findings to researching the main asteroid belt as well as the capture of Trojan asteroids by gravitational sources associated with Jupiter. They will also investigate models of dusty rings seen in other planetary systems to see what information can be obtained. Further information and a video of the creation of our outer ring can be seen here.

Space probe roundup

There’s a few probes out there, gathering data in the solar system, so starting from the inner planets, today’s news includes:

Venus Express has been watching a vortex playing in the atmosphere above the south pole of Venus. In 1979, the Pioneer Venus mission spotted a vortex above the north pole and on arrival in 2006, Venus Express found its southern twin. However, continuous recording of the phenomenon has shown that the double-eyed appearance of the vortex was simply a coincidence. Other vortices have since come and gone at the south, leaving the double eyed feature nowhere to be found. Full details are here.

Sticking with Venus Express, but delving lower into the atmosphere, lightning discharges on the second planet from the Sun have been confirmed as happening as frequently on Venus – one hundred times a day – as on Earth. The storms are strongest on the dayside, where the Sun provides the energy for cloud particles to collide and rub together, and also strongest towards the equator, for the same reason. The signals, previous detected by other probes using different instrumentation, were detected using Venus Express’s magnetometer and were apparent from the earliest times after insertion into orbit. Full details here.

Onto Earth now and a crater seen in satellite images bundled into the Google Earth software has been confirmed as being an impact feature. The feature was spotted in 2008 in images of the Egyptian desert and has been measured at 45 metres diameter and 16m deep. The crater was forged by the impact of a 1.3m meteorite weighing in at 10 tonnes (one tonne of which has now been collected up) sometime in the last several thousand years. The crater has evaded the geological processes that tend to erode such features and seems to have also escaped notice from human eyes in all that time. More on the discovery and confirmation of Kamil crater (including a google maps page showing the thing) can be seen here.

Three years of data from the SMART-1 mission to look at the Moon have been released by ESA. The three scientific instruments on board the probe were: the Advanced Moon micro-Imager Experiment (AMIE), which was a camera in visible and near infrared light, which watched the terrain changing as the shadows changed and so mapped the southern pole of the Moon to a resolution of 40m per pixel; the SMART-1 InfraRed Spectrometer (SIR), which watched the spectrum of the Moon in the 0.9-2.6 micrometer wavelength range, enabling mapping of pyroxene and olivine in solidified lunar magma exposed by asteroid impacts; the Demonstration of a Compact Imaging X-ray Spectrometer (D-CIXS), which mapped the Moon in the 0.5-10keV photon energy range, enabling x-ray reflection spectroscopy of some heavy elements. Fortunately for D-CIXS, a high energy solar flare provided additional x-ray flux enabling some of the elements that would normally be producing very dim signals to shine brightly enough to be confirmed. The data can be found here.

Further out and Mars Express has been used to examine the unusual behaviour of carbon dioxide ice in the Martian polar cap. Observations of the ice showed unusual behaviour as the cap receded in warmer times. The signal of the CO2 is seen to weaken and vanish as it sublimates from ice to gas, but then not long after, the signal suddenly returns before vanishing again. This fade in, it was hypothesised, could be due to a protective layer of dust or water ice protecting the underlying CO2. As there was no change in brightness, as there would be if white ice gave way to dark dust, researchers concluded water ice, invisible to the instruments they were using, must be the insulating layer. The Martian polar caps contain a mixture of water ice and CO2 ice. CO2 sublimates at a lower temperature, so what was happening was the exposed CO2 vanished, leaving a water ice shell (added to by condensing water ice from warmer, lower latitudes) and underlying CO2. Then there came the problem of why the water ice was suddenly stripped away revealing lots of CO2 to provide the second signal. Models of downward flowing winds created by the warming showed that these were capable of doing the stripping, lending the final piece of the theory. Full details here.

The Rosetta probe is set for a date with the Comet 67P/Churyumov-Gerasimenko in May 2014. Computer models of the three dimensional shape and motion of the comet have been used to assess what part of it will be least prone to outgassing as the block of rock and ice closes in on the Sun. The results suggest the southern hemisphere will be the best place for Philae, the lander delivered by the probe, to hook on and sample the comet material. Before the probe meets the comet, this hemisphere will receive the largest amount of sunshine, eroding the outer crust and exposing pristine material within. By the time the probe meets the comet, and after delivery of the lander, the north pole of the comet will be in the glare of the Sun, and so most prone to outbursts. The lander will use harpoons and jets to hook onto the comet during its studies. Full details here.

Cassini will be performing the first in a series of Titan flybys over the next eighteen months later today. The aim will be to supplement climate studies of the distant satellite of Saturn, more details here.

Cassini has also been taking a good look at the parent body in the infrared. Using the Visual and Infrared Mapping Spectrometer, Tom Stallard of Leicester (and formerly UCL) has been observing changes in the southern lights of Saturn to compare with other processes going on in Saturn’s magnetosphere, the aim being to connect the two. The aurora of Saturn are complex and involve both large scale motions of the magnetosphere – contractions and expansions caused by the uneven passage of the pulsed solar wind – and small scale structure such as disruption of particle and energy flows by the moons of Saturn inside the magnetosphere. More details of his infrared work are here and some images of ultraviolet auroral signals from Saturn and Jupiter by the Hubble Space Telescope are here.