by VirtualAstro | Jun 11, 2011
Originally posted on Dark Sky Diary by Steve Owens (@darkskyman on twitter)
Over the next couple of months ESA’s Cluster spacecraft are going to get very close to Earth, with the orbit of one of the four satellites dropping as low as 200-300km from the Earth’s surface. This is low enough that you may indeed be able to spot – and if you’re skilled enough, take pictures of – the spacecraft.
ESA's Cluster Spacecraft
The four satellites – named Rumba, Salsa, Samba and Tango – were launched in 2000 to study the interaction between the Earth’s magnetic field and the Sun’s solar wind, and because there are four of these satellites, orbiting Earth in a tetrahedral configuration (i.e. one satellite at each of the apexes of a triangular pyramid) the Earth’s magnetosphere can be mapped in 3D.
The solar wind interacts with the Earth's magnetosphere
During June and July 2011 one of the Satellites, Cluster II (Salsa), will come within 200-300km of the surface of the Earth, which means there is a chance you might see it.
They might not be visible from the UK – in fact the British Astronomical Association suggest that the best chance of seeing these satellites is from latitude 20-30 N, so for anyone holidaying in the Canary Islands this summer there’s a chance you’ll catch a glimpse. There is a chance they’ll be visible further north too, from Europe. In any event, the brightness of the satellites is unknown at this stage, and so we can’t tell how easy it will be to spot, even if it’s visible from where you are.
The best way of checking whether the satellites are visible from where you are is to use the excellent Heavens Above website. Enter your observing location and then under “Satellites” click “select another satellite”, then in the “Satellite Name” box type “Cluster%” (the % is important). You can then select each of the four Cluster satellites and in the upper right corner of the information panel you can click “Passes (visible)” to see if there are any passes worth watching for from your location.
This will give you five crucial bits of information:
- date of passes
- magnitude (brightness) of the satellite (it is currently showing ?)
- the time, altitude, and direction of when the visible pass starts
- the time, altitude, and direction of when the satellite at its highest in the sky
- the time, altitude, and direction of when the visible pass ends
ESA have even announced a competition on Facebook, where they are encouraging people to try and image the satellites! This is no mean feat, but not without precedent. In fact a number of very experienced astrophotographers have caught images of the International Space Station as it orbits about 360km overhead. One of my favourites is this one by Thierry Legault, of the space shuttle Atlantis approaching the International Space Station where both were silhouetted in front of the Sun.
Thierry Legault's incredible image of Atlantis and the ISS taken from Earth
Happy satellites hunting, and let me know if you catch a glimpse!
(HT to the BAA for bringing this to my attention).
by VirtualAstro | Jun 2, 2011
Noctilucent Clouds
Noctilucent Clouds 2009 Panorama Credit: VirtualAstro
Soon you may see an eerie spectacle on clear summer nights if you are located at latitudes between 50° and 70° north and south of the equator: Noctilucent Clouds.
These ghostly apparitions are a delight to see and are quite rare. It is incredibly difficult to predict exactly when they will appear, but we do know they should begin to appear soon.
The season for Noctilucent Clouds (Noctilucent = Latin for “Night Shining”) starts early June and continues into late July. They are seen just after dusk, or before dawn and an apparition can last around an hour.
These mysterious clouds, with their bizarre tenuous wispy shapes reminiscent of ripples in sand or the changing surface of a pool of water, spread like a glowing web across the northern sky. Colours can range from brilliant whites, with tinges of blue, pink and orange.
Formed by tiny ice crystals, they are the highest clouds in the Earth’s atmosphere, located in the mesosphere at altitudes of around 76 to 85 kilometers (47 to 53 miles) almost at the edge of space.
They are normally too faint to be seen, and are visible only when illuminated by sunlight from below the horizon, while the lower layers of the atmosphere are in the Earth’s shadow. Noctilucent clouds are not fully understood and are a recently discovered meteorological phenomenon, only being recorded for about 120 years.
Noctilucent clouds can only form under very restrictive conditions, and their occurrence can be used as a guide to changes in the upper atmosphere. Since their relatively recent classification, the occurrence of noctilucent clouds appears to be increasing in frequency, brightness and extent.
There is evidence that the relatively recent appearance of noctilucent clouds and their gradual increase, may be linked to climate change. Another recent theory is that some of these bright displays come from particulates and water vapour in the atmosphere left over from Space Shuttle launches.
How can you see Noctilucent Clouds?
Over the next couple of months look north during dusk and dawn and try and spot this mysterious and elusive phenomenon. They are best seen when the sun is between 6 and 16 degrees below the horizon, and seem to occur more frequently in the Northern hemisphere than the Southern.
Good luck!
by VirtualAstro | May 18, 2011
23rd to 30th of October 2011
In celebration of its 5th year, the Salisbury Star Party will be hosting AstroParty with 7 days of Astronomy activities for people of all levels of interest and ability. All are welcome and those who attend will enjoy dark skies, a fantastic location, great company and lots and lots of fun. The organisers intend to make the Astro Party one of the biggest and best astronomy events in 2011 and beyond.
Venue:
The event will be held in a lovely and spacious campsite in the pretty village of Sixpenny Handley in the glorious Wiltshire countryside, (an area of outstanding natural beauty) with dark skies and excellent facilities including a large cafe/ conference area.
The site is located within 300m of the Village High Street. There are a variety of shops, including General Stores/Newsagents, Butchers, Post Office, Gift Shop and also a Public House. The village church backs on to the campsite, which adds a little more of that country atmosphere to the venue.
The historic City of Salisbury and the market towns of Blandford Forum, Wimborne Minster, Shaftesbury and Ringwood are all easily reached within 30 minutes drive.
If you aren’t keen on camping, there are local B&B’s and hotels etc in the surrounding area.
Activities:
Star Party – Running for all of the 7 nights with around 70 to 100 experienced astronomers at its core, the Star Party is the main part of the event, so bring your kit if you have any, join in and take advantage of observing and imaging with a large group, whatever your level of experience? You don't even need to bring a telescope, just use your eyes.
Imaging World Record – More info coming soon?
Inflatable Planetarium Shows – Big planetariums with big shows all topped off with what’s up guides.
Talks – A daily program of talks by famous and experienced people in the world of astronomy.
Tweetup – A social gathering of social media. Twitter and Facebook users meet and tweet with your online friends here.
Tours of the Sky – live and real tours of the sky by experienced astronomers.
Telescope and Equipment Workshops – Ask for advice or get help with astronomical equipment.
Trade Stands – More info and who is coming soon?
Competitions – A raffle for that nice telescope or piece of imaging kit?
Hospitality – There will be a hog roast on the final Saturday, and there is a cafe which is open through the week. We hope to have additional tents where you can warm up, tweetup, get a coffee, have some soup, or somewhere to chill and drink your beer. There is a licensed bar on site and a pub in the village.
More activities and services will be added to the program before the event starts.
A website will be launched shortly where you can look for additional information and book your tickets for the event.
Please book tickets here
Let’s Make AstroParty, hosted by the Salisbury Star Party one of the biggest and best astronomy events and we hope to see you all there.
by VirtualAstro | Mar 19, 2011
Originally posted on Dark Sky Diary by Steve Owens (@darkskyman)
Today, Friday 18 March 2011, it is the Spring Equilux throughout the UK (and possibly elsewhere too*) meaning that there are almost exactly 12 hours between sunrise and sunset.
Sunrise
This date differs from the Spring, or Vernal, Equinox (2321 GMT on Sunday 20 March 2011) for a variety of reasons, which I explain in a previous post but here is a list of sunrise / sunset times for a variety of towns and cities throughout the UK:
| Town / City |
Sunrise |
Sunset |
| Aberdeen |
0617 |
1817 |
| Glasgow |
0626 |
1826 |
| Belfast |
0632 |
1833 |
| Newcastle |
0615 |
1815 |
| Manchester |
0617 |
1818 |
| Birmingham |
0616 |
1817 |
| Cardiff |
0621 |
1822 |
| London |
0609 |
1809 |
As you can see the time between sunrise and sunset is not exactly 12 hours everywhere but this is the day of the year when that is closest to being true everywhere*. Yesterday the sun rose a couple of minutes later and set a couple of minutes earlier, and tomorrow the sun will rise a couple of minutes earlier and set a couple of minutes later, as the days lengthen.
Also, the reason that sunrise and sunset does not occur at the same time everywhere* is due mainly to the longitude of the town, the further east a town is the earlier it sees the sun in the morning, and the earlier it loses it again at night.
So happy Equilux everyone*!
* interestingly, the equilux does not occur on the same same day for everyone, it depends on your latitude. The closer you are to the equator the earlier the date of your equilux. For example the equilux in most US cities occurred yesterday, 17 March, and in cities near the equator there is never a day with exactly twelve hours between sunrise and sunset! Take Quito, the capital city of Ecuador (latitude 0 degrees 14 minutes south) for instance. The length of day there only ever varies between 12 hours and 6 minutes long and 12 hours and 8 minutes long!
by VirtualAstro | Mar 16, 2011
I am often asked or hear about bright fireballs in the sky, often reported by non astronomy minded people, so when you ask where was it and what direction it was travelling etc, you get very sketchy information back like: It was over my house and headed towards town, I think?
Only if you have many sightings of the same fireball can you interpolate where it was and what direction etc it was travelling? Things are going to be made a lot easier if you live in some parts of the United States.
NASA is building a network of "Meteor Cameras" in a few of States in the US called the "All-sky Fireball Network". This is a network of cameras set up by the NASA Meteoroid Environment Office (MEO) with the goal of observing meteors brighter than the planet Venus, which are called fireballs. The collected data will be used by the MEO in constructing models of the meteoroid environment, which are important to spacecraft designers.
The Network will eventually consist of up to 15 overlapping cameras in north Alabama, northwest Georgia, and southern Tennessee, placed on public buildings and schools. The network will use sensitive black and white cameras which are able to see the whole of the sky (All Sky).
Because the cameras have overlapping fields of view, more than one camera can see the same meteor at the same time, helping in getting data about its trajectory and with clever data collection software, ascertain if the meteor came from a comet or an asteroid.
NASA’s All-sky Fireball Network uses ASGARD (All Sky and Guided Automatic Realtime Detection). ASGARD not only handles all the data processing (which is considerable) it also automatically pushes the results to the web. See the results here: http://fireballs.ndc.nasa.gov
