Don’t forget to change the clocks this Saturday evening and claim your annual extra hour in bed on Sunday morning.
At 1.00 am GMT (2.00 am BST) on Sunday 31 October 2010 clocks go back one hour as civil time changes from British Summer Time (BST) to Coordinated Universal Time (almost identical to Greenwich Mean Time).
The Ninth European Parliament and Council Directive on Summer Time Arrangements states that summer (or daylight saving) time will be kept between the last Sunday in March to the last Sunday in October. The changes will take place at 01.00 GMT.
Find out more about daylight saving time and British Summer Time at nmm.ac.uk/bst.
21 October 2010 – Astronomers have confirmed the discovery of the most distant astronomical object yet known – the galaxy UDFy-38135539, over 13 billion light years from Earth.
This also makes it the furthest back in time scientists have been able to see, to the early Universe just 600 million years after the Big Bang during what’s known as the epoch of re-ionisation. During this period the fierce UV light from the first populations of stars would have stripped electrons from the opaque hydrogen fog which filled much of the young cosmos, gradually making the universe transparent.
However, it appears that the light from UDFy-38135539 would not have been
strong enough on its own to clear the hydrogen fog surrounding it,
which indicates that there must be other fainter, less massive galaxies
in its neighbourhood which helped clear the fog.
UDFy-38135539 was spotted in the area of space known as the Hubble Ultra Deep Field, a small region of space in the constellation Fornax. The galaxy was one of a number of interesting candidates for study found in a 48-hour exposure image acquired with Hubble’s new Wide Field Camera 3 in 2009. Astronomers used the SINFONI spectrograph instrument attached to the Very Large Telescope (VLT) on Mount Paranal to measure the exact distance to UDFy-38135539. The spectrograph is able to determine the redshift of the light from the galaxy – the extent to which it has been stretched by the expansion of the Universe.
The findings were published today in the journal Nature. The lead author of the paper is Matt Lehnert of the Observatoire de Paris.
On 20 October 2010, Comet Hartley 2 (103P/Hartley) will pass within about 11 million miles (0.12 AU) of the Earth. This will be its closest approach since it was discovered in 1986, and one of the closest approaches of any comet in the last few hundred years. At this time, the comet should be visible in the constellation Auriga.
Image: Hartley 2 in Cassiopeia, 28 Sep 2010 (crop). Credit: NASA/MSFC/Bill Cooke, NASA’s Meteoroid Environment Office.
There will be a great opportunity for astrophotographers between 7-9 October as the comet passes close to the beautiful Double Cluster in Perseus. It is then expected to pass near the open cluster NGC 1528, also in Perseus, by 14 October. Don’t forget to enter your photographs of the comet in the 2011 Astronomy Photographer of the Year competition which opens in January.
Viewing Hartley 2
Meanwhile over the next few days Hartley 2 should become increasingly visible with the aid of binoculars or a small telescope, and possibly even to the naked eye.
The comet is diffuse (its light is spread out over a wide area) so to see it you need a dark sky location free of city lights. The technique of averted vision – looking slightly to one side rather than straight on – is also helpful in locating faint objects. The comet will probably appear as a grey smudge of light or as a faint, fuzzy star. Heavens-Above.com has a useful locator chart.
After 10 October the Moon will start to make it harder to see the comet, so until 20 October best viewing time will be after moonset.
On 28 October, the comet will reach perihelion (closest approach to the Sun). Finally, on 4 November, NASA’s EPOXI mission (previously Deep Impact) will fly by the comet, with a closest approach of 435 miles.
It’s estimated that Hartley 2 will next come to perihelion in 2017, around 20 April.
On 29 September 2010 a team of astronomers announced the discovery of an Earth-sized exoplanet Gliese 581g in the habitable (‘Goldilocks’) zone of a nearby red dwarf star. The planet has a mass three to four times that of the Earth, which suggests that it is probably a rocky planet with enough gravity to hold on to an atmosphere. Altogether the findings could make Gliese 581g the most Earth-like exoplanet yet found, and the strongest contender so far for a potentially habitable planet – one that could sustain life.
Gliese 581g is tidally locked to its host star, with one side always facing the star in perpetual daylight. The most habitable zone on the planet would be the ‘terminator’ – the line between shadow (night) and light (day).
The host star, Gliese 581, is located 20.5 light years from Earth in the constellation Libra. Among the six planets so far discovered orbiting the star, two others (planets c and d) lie at the edges of the habitable zone, and some astronomers still think planet d may be habitable if it has a thick enough atmosphere.
The new findings have been made by the Lick-Carnegie Exoplanet Survey, led by Steven Vogt (University of California, Santa Cruz) and Paul Butler (Carnegie Institute, Washington). They are based on 11 years of observations of Gliese 581 at the W.M. Keck Observatory in Hawaii, made using the HIRES spectrometer on the Keck I Telescope. This allows precise measurements of a star’s radial velocity, which can reveal the presence of orbiting planets whose gravitational pull causes periodic changes in the host star’s radial velocity.
The team’s findings are to be published in The Astrophysical Journal and have been posted online at arXiv.org.
Steven Vogt believes that the surprising speed with which they have been able to find a nearby star system with a potentially habitable planet means that there could be ‘tens of billions of these systems in our galaxy’.
Find out more
Life, but as we know it? Sci-Fi-London Oktoberfest
If you’re interested in the possibility of life on other planets, join us on 14 October when the Royal Observatory, Greenwich teams up with Sci-Fi-London for a special night investigating extraterrestrial life in science,
fiction and comedy. All ticket holders will see our exclusive new
planetarium show Astrobiology and will also have the chance to sign up for a range of other activities on a first-come first-served basis including a preview screening of Gareth Edwards’ new sci-fi movie Monsters, an adventure game around the Observatory, telescope viewing and a lighthearted tour of the Observatory’s meteorite collection. Find out more
Book online or call 020 8312 6608.
Astrobiology: the hunt for alien life (5-week course)
If you want to study life beyond Earth in more detail, why not sign up for this short course with Dr Lewis Dartnell. ‘Astrobiology’ is a brand new field of science, encompassing research
into the origins and limits of life on our own planet, and where life
might exist beyond the Earth. But what actually is ‘life’ and how did
it emerge on our own world? And where else might provide conditions
suitable for life, either in our own solar system or among the
exoplanets so far discovered?
Book online or call 020 8312 6608.