The annual Perseid meteor shower reaches maximum activity on August 12th at 5pm BST. So both the pre-dawn period on the 12th and the night of 12th/13th could see the highest activity. This year circumstances are very favourable as the young Moon will have set soon after 10pm BST on the 12th, leaving the rest of the night Moon free.
The shower radiant climbs higher in the sky as the night progresses. By 11pm BST the radiant, below Cassiopeia, is about 40 degrees up in the North East. If it is clear then away from streetlights it should be possible to see a meteor on average about once a minute at peak although for several nights either side of maximum it is worth observing. What often happens is that several come along in quick succession, then a gap before the next burst.
Useful dark sky observing periods return this month free from the summer twilight. By the end of the month astronomical twilight ends by 10pm BST.
Saturn is still visible in the evening twilight in the West but by months end is getting low. A young crescent Moon will be near the ringed planet on the 12th. A superb image was recently captured by the Cassini probe looking back at Earth with the benefit of the Sun being eclipsed by Saturn. Although less spectacular than our view of Saturn, the pale blue colour of our little island in space is striking, with the Moon alongside.
Full Moon this month is on the night of the 20th/21st, reaching 30 degrees in altitude when due South.
Through August the early autumn constellations become more prominent in the East, including Pegasus and Andromeda. From dark sites it is just possible to see the Andromeda Galaxy (M31) with the unaided eye. Averted vision can help (looking just to the side of the target).
M31 is the most distant object readily visible without optical aid, over 2 million light years away. Like our own Milky Way galaxy, Andromeda is a “grand-design” spiral. In binoculars it appears as a large elliptical hazy patch. With a telescope it is possible to see more detail and structure, including some of the many dwarf galaxies that orbit around it.
A recent paper suggests that as well as our future predicted interaction with our “sister” galaxy, we have actually been in a gravitational dance with M31 for billions of years with a previous ancient glancing collision billions of years ago evidenced by the polar rings that both galaxies have. The paper also raises the stakes on the Dark Matter V MOND (Modified Newtonian Dynamics) debate.
James Abbott is an astronomer, NEAS member and CfDS Regional Information Officer.
On Wednesday 21st March, we welcome guest speaker Jerry Stone FBIS FRAS who will be talking about Cassini-Huygens mission to the great planet Saturn – the titular “Lord of the Rings”.
The Cassini spacecraft is currently orbiting the planet Saturn after a journey of more than 7 years. It carried the Huygens probe which separated from Cassini in December 2004 and descended to the surface of Titan (Saturn’s largest moon) in January 2005. In this talk, you’ll hear about the exploration of Saturn - from before we knew it had rings, up to the latest results.
Jerry Stone is a freelance presenter on astronomy and space exploration, has given talks on space for over 40 years and is the author of “One Small Step”. He runs Spaceflight UK and presents space workshops for schools all over the UK.
The lecture is open to everyone, all are welcome. It takes place at the Henry Dixon Hall, Rivenhall End on Wednesday 21st March at 7:30pm. Entry is £4 for non-members. For further information on how to get there, see the Events page.
Cassini-Huygens was a joint mission by NASA, ESA and ASI to study Saturn, its rings and moons. It was launched on 15th October 1997 onboard a Titan 1VB Centaur Rocket and, after a journey of 6 years and 9 months, it entered into orbit around Saturn on July 1st 2004. The attached Huygens probe was released from Cassini on Christmas Day 2004 and landed on Titan two weeks later.
The mission has had two extensions since then, in 2008 and 2010, meaning the spacecraft will stay in service around Saturn until 2017.
At 22 feet high and 13 feet wide, the spacecraft is the largest and the most complex built to date, featuring over 1,630 interconnected electronic components, 22,000 wire connections and over 8 miles of cablings – at launch it weighed in at 5,600 kilograms (12,000lbs).
In June 1999, Cassini’s velocity was recorded at 44.0 kilometres per second (98,346 mph). Radio signals to Cassini take anywhere between 68 to 84 minutes to travel from the Earth.
The model has been composited here by Paul Kemp, with a NASA/JPL Cassini image of Saturn.
The plans were, like Galileo, taken from those designed for paper models, meaning features like fuel cells would be two round discs slotted together at 90 degrees. The antenna dish was formed from thick plastic card, softened by a heat gun and pulled down over a bottom of a truck oil filter to give the correct dish shape, then trimmed up and detailed.
To make the main body of the space craft plastic card was rolled up, and ribs were added using small strips cut and shaped to fit the body. Various pieces went into making the cameras, gyros and rocket engines. The magnetometer boom was made from 0.6 mm plastic rod and over 700 pieces went into this section alone. The model was then painted and a base was made to display the model. In total, it took about 9 months to build.
In comparison to the actual spacecraft, this model is 170mm long, 90mm wide, with the magnetometer boom 300mm long and the dish 120mm in diameter.
Just in … crisp, detailed raw images from Cassini’s close flyby of Dione earlier today, including views of its north polar region at a
Notice especially the long, bright ice cliffs crossing a region of the moon that, during the Voyager mission, became known as the `wispy terrain’. Voyager couldn’t resolve what Cassini has since seen in great detail: That this terrain is not crossed by wispy-looking bands of hummocky bright ice, as was previously thought, but instead is laced with organized sets of fractures that reveal bright, clean, sub-surface ice.
… and check it all out for yourself.
Cassini Imaging Team Leader
Space Science Institute
Don Gurnett is a scientist from the University of Iowa whose research includes recording and analyzing sound waves from space.
You can listen online to some of these sounds (from all over the Solar System), which have been recorded by a variety of spacecraft over the past 40 years (including Voyager and Cassini). You can also watch animations of the sound with the specrogram of the wave.
On Monday, the Cassini spacecraft will fly very close to the south pole of Saturn’s icy moon Enceladus, and will return the best images so far of that region.
Cassini discovered that Enceladus has plumes of water spurting up from deep inside the moon, indicating the presence of liquid water. This obviously makes Enceladus a very juicy target for Cassini, and the images should be spectacular.
Stay tuned to sites like the Cassini CICLOPS page, which will have the latest images in all their high-res glory.