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2015: The Year of Dwarf Planets and Small Solar System Bodies

We’re currently living through a very exciting time in space exploration, with a small armada of robot space probes visiting previously unexplored corners of our solar system. Here’s just a few of the amazing discoveries we’ve made in the past few weeks.

New Horizons

New Horizons

This year sees us make close encounters with two of the largest dwarf planets, as New Horizons flies past Pluto for the first time, and Dawn continues to orbit the giant asteroid Ceres. All this as the Philae Lander continues to try to make contact with us from the surface of Comet 67P/Churyumov-Gerasimenko as its parent spacecraft Rosetta follows the comet around the Sun.

Each of these missions is very exciting in its own right, but to have all three happening at once is incredible.

Rosetta and Philae Latest

The Rosetta Orbiter arrived at Comet 67P/Churyumov-Gerasimenko in August last year, and the Philae lander descended onto the comet’s surface in November, carrying out its science mission for 60 hours before its batteries died. Rosetta has continued to produce great science since then; its latest scoop was the discovery of what appear to be sink-holes on the comet’s surface.

Sink Holes on Comet 67P

Sink Holes on Comet 67P

All this while Philae tries to make contact with us, and Comet 67P begins the outgassing that will eventually form its tail as the comet makes its closest approach to the Sun on 12 August 2015.

Comet 67P/Churyumov-Gerasimenko begins outgassing

Comet 67P/Churyumov-Gerasimenko begins outgassing

Dawn Latest

The Dawn spacecraft arrived at Ceres in March 2015, after having spent over a year orbiting the smaller asteroid Vesta. Ceres is the largest of the asteroids, so large in fact that it’s considered a dwarf planet, its gravity having pulled it into a spherical shape.

More and more mysteries are arising as a result of Dawn’s asteroid mission including: what are these bright patches inside craters on Ceres’ surface?

Bright spots in the surface of the Dwarf Planet Ceres

Bright spots in the surface of the Dwarf Planet Ceres

and: what’s a mountain doing on an asteroid?

A mountain on an asteroid

A mountain on an asteroid

New Horizons Latest

Stay tuned for even better images of Pluto as New Horizons speeds towards its 14 July flyby at close to 60000kph. For now the best images we have of Pluto and its moon Charon are from New Horizons’ Long-Range Reconnaissance Imager, which shows features on the surface of the distant Dwarf Planet, which we’ll see in better detail in the next couple of weeks.

Pluto and Charon, real colour

Pluto and Charon, real colour

Other Missions

This is on top of all of the other missions going on up in space right now: Cassini continues to send back breath-taking images and data from the ringed planet Saturn and its moons; no fewer than five spacecraft are currently in orbit around Mars – NASA’s 2001 Mars Odyssey, , Mars Reconnaissance Orbiter, and MAVEN, ESA’s Mars Express, and India’s Mangalyaan – while two intrepid rovers – Opportunity and Curiosity – explore Mars’ surface; and our own Moon is orbited by the Lunar Reconnaissance Orbiter.

We’ll add to this over the next few years, as the Juno probe reaches Jupiter in summer 2016, and as the Japanese mission Hayabusa 2 enters into orbit around an asteroid in 2018 and returns a sample to Earth on 2020.

Catch a Glimpse of ESA’s Cluster Spacecraft

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).

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