Orbit: Episode Two

    The second instalment of the series follows the Earth's journey from the start of January to the Spring Equinox in March. Available on iplayer. What did you think?

    Kate begins the film on a day with a very significant point in our Earth's journey - Perihelion. Kate climbs Aonach Mor mountain, one of the highest mountains in Scotland, which brings her as close to the Sun as she'll ever be for the entire year.

    This however is not because of where she is but because of the point the Earth has reached in its orbit around the Sun. In fact we kick started our blog on this day just over a year ago, when we explored the elliptical shape of our planet's orbit and how significant this was to our understanding of Earth's climate.

    Later in the film Helen explains how the proximity of the Earth to the Sun doesn't guarantee warmth - which brings us to the tilt of the Earth (23.4 degrees) - a theme we explore in further detail in episode three.

    Throughout this episode Kate and Helen explore the increase in solar radiation and how land and ocean respond to it.

    Kate drives over a frozen lake in Canada with an ice road trucker in one of the coldest places in that region and learns how important this ice formation is to connecting communities.

    In this film we also tackle ice ages and how over time, as Earth has repeated it's annual journey, it's climate has changed.

    Helen dives under water in Belize to discover how sea levels have risen and fallen over time due to ice age - and explores the three cycles that need to be right in order for another ice age to exist.

    What did you think of episode two?

    (There are a total of three episodes in this series)

    Saturn's super-storms quite unearthly...

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    Mark Thompson Astronomy Mark Thompson Astronomy | 18:00 PM, Friday, 11 November 2011

    Distance travelled ~ 809'788'800 km

    High winds are a common occurrence on Earth but they don't often reach more than 150km/h. The record is held by the Tropical Cyclone Olivia as it moved across Australia in April 1996 which battered the land with gusts of 408 km/h. This is nothing compared to the rather more serene and beautiful looking planet Saturn. High in the atmosphere of this gas giant the wind speeds have been measured at a staggering 1800km/h.

    The concept of what causes wind, which is effectively the flow of gas from one place to another, is pretty simple to understand. Take the Earth for example; warmth from the Sun heats the surface which then in turn heats the atmosphere in contact with it. As the air warms, it becomes less dense than the surrounding air causing it to rise which results in an area of low pressure as 'less air' is present. Other surface air will then rush in to effectively fill the void left from the rising air and we experience that as wind.

    The storms we see on Earth are just extreme versions of this with areas of particularly low pressure at the centre. Typically they form over the oceans which are a vast reserve of energy. Water is very good at storing and retaining incoming solar energy and its this along with the moisture that gives storms their awesome power.

    On Saturn the extreme storms that drive the winds are very similar in structure to those on Earth with low pressure systems but it's the source of the energy which sets them apart. Instead of vast bodies of water, the heat driving the storms on Saturn comes from deep within the planets core. When it formed around 5 billion years ago heat was generated when the pieces from the proto-planetary disk crashed together and its the slow but steady release of this energy which has driven Saturn's super-storms.

    NASA's Cassini spacecraft captures a view of storm churning through the atmosphere in Saturn's northern hemisphere

    Image credit NASA

    The Cassini spacecraft witnessed first hand one of Saturn's ferocious storms whilst it was orbiting the planet in December 2010. It was quite lucky given that Saturn is usually relatively storm free, unlike Jupiter however the lucky break gave planetary scientists a unique insight into the local weather system. The images show the storm covering nearly 4 billion square km and analysis of the lightning strikes showed a ten times more flashes than in other storms studied since 2004.

    Spacewatch: CME, Mercury and Venus?

    Stephen Marsh Stephen Marsh | 15:30 PM, Wednesday, 5 October 2011

    Distance travelled ~ 714'327'200 km

    While we have been enjoying the wonderful sunshine down on Earth (especially the recent record october warmth in the UK) - space has also been throwing up some pretty stunning weather. Yesterday, October 4th, a massive solar flare exploded from the surface on the far side of the Sun. It blasted a spectacular coronal mass ejection or CME into space. A CME is a massive burst of solar wind and plasma containing electrons and protons that blast out from the Sun's surface. They are associated with solar flares and tend to develop in areas of high solar activity such as Sun spots.

    The October 4th CME was recorded by the Solar and Heliospheric Observatory

    Scientists from the Goddard Space Weather Lab have plotted the course of the CME and discovered it is heading directly for the planet closest to the Sun, Mercury. The cloud of highly energised plasma and particles won't affect the planet but could disrupt the MESSENGER probe in orbit around Mercury.

    cme forecast track

    To watch the moving image click here

    It is possible that the CME may then hit Venus on Oct. 6th, but it is not predicted to hit Earth.

    What happens when CME's hit Earth?
    When CMEs do come our way the shockwave from the highly energized particles can cause a geomagnetic storm that can disrupt our magnetic shield. This can trigger dynamic auroras or Northern Lights [aurora borealis] in the northern hemisphere or Southern Lights [aurora australis] in the southern hemisphere. CMEs hitting earth can also cause disruption to radio transmissions, damage satellites and cause power cuts by knocking out electrical power cables.

    They don't present a health risk for us on the surface because of our protective magnetic shield and atmosphere. But they can present problems for astronauts and even people in high altitude planes due to increased risk of exposure to radiation. But it is thought that any long-term health risk are unlikely.

    How likely is 2013's 'perfect solar storm'?

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    Dr Lucie Green | 11:30 AM, Tuesday, 23 August 2011

    Distance travelled ~ 603'268'000 km

    (Lucie Green is a solar researcher based at the Mullard Space Science Laboratory, UCL's Department of Space and Climate Physics. She studies activity in the atmosphere of our nearest star, the Sun, with particular focus at immense magnetic fields in the Sun's atmosphere. Lucie is also a Science writer and has been involved in a variety of Science programmes such as Sky at night and recently Radio 4's programme the infinite Monkey cage.)

    It seems that barely a week goes by at the moment without the Sun being in the news, for seemingly contradictory reasons. One minute we are being told that the Sun is going to cause a global disaster as the result of super-sized solar activity, the next that Sun is going into hibernation. So, what exactly is going on?

    CME blast 2 December 2003

    Courtesy of SOHO/EIT consortium. SOHO is a project of international cooperation between ESA and NASA

    The Sun has a cycle in which its magnetic field pulses in size and complexity roughly every 11 years. Coronal mass ejections (CMEs), huge bubbles of magnetic field containing charged particles, are a natural part of this cycle. At the moment we are approaching solar maximum (expected to occur around 2013) which means that the number of ejections is on the rise and so too are some worrying consequences here on Earth.

    CMEs can inject charged particles into the Earth's magnetic field which, if accelerated, lead to the beautiful aurora. The flipside is that these particles can also damage our satellites, lead to satellite failure and produce currents in our power lines causing problems for national power grids. Most notably, in 1989 a transformer in the Canadian national grid failed due to such currents and several million people lost their electricity for over nine hours. So, the increasing number of CMEs is good news for people wishing to view the aurora but bad news for our space-based and electrical infrastructure.

    Some news articles are predicting that in 2013 the perfect solar eruption will occur that will cause a global disaster through the simultaneous failure of electricity networks all over the world and the loss of the satellites that modern society relies on for communication, navigation and banking. However, many aspects need to come together to produce this 'perfect solar storm' which makes such an event hard to forecast. This scenario isn't pure fiction though.

    The reasoning is based on studying previous events, in particular a solar eruption that occurred in 1859 which produced such a strong display of the aurora that they were seen down toward the equator. If this event repeated itself today it is likely that the worldwide damage caused would cost a trillion dollars. [For more information on how coronal mass ejections affect us: NOAA/Space weather prediction center ]

    No individual solar cycle is the same as the next though, and this brings me to another reason that the Sun has been in the news. The Sun has only recently come out of the deepest solar minimum for 100 years. Things have been very quiet on the Sun. So whilst some are worried that the Sun might cause global destruction, others are worried that the Sun is going to switch off. On the face of it these are contradictory stories but on closer inspection this is not so.

    On the timescale of a few years solar activity and the number of CMEs is on the rise and we will experience more effects on our technology. However, on the timescale of decades, it looks like the magnetic cycle of our Sun may decline. This idea could be extrapolated to conclude that the Sun will switch off altogether but in reality there is an very small chance of this happening. Things may quieten down, but they will pick up again.

    Ultimately, we are living in a gusty outflow of magnetic field and charged particles coming from the Sun. This has led to a new era of 'space weather' prediction where we are monitoring the near-Earth space environment to make sure we protect ourselves from the harmful effects of the Sun's emissions. Whatever level of activity the Sun decides to produce we will feel the consequences. Understanding and predicting the weather in space should be given a high priority.

    Double CME hit Earth's magnetic field 5 August producing beautiful Auroras

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    Aira Idris Aira Idris | 11:00 AM, Monday, 8 August 2011

    Distance travelled ~ 564'622'400 km

    auroral display Scotland

    This photo was taken on August 5, 2011 in Elgin, Scotland, by Alan Tough.

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