STARGAZER
APRIL 2017
ONLINE ASTRONOMY SOCIETY ACADEMY
Image Of The Month - Page 4 Ancient stardust sheds light on the first stars - Page 5 Experiments show Titan lakes may fizz with nitrogen Page 6 GAS GIANT CLOSE TO FIERY END AS KELT-16B MOVES CLOSER TO ITS STAR - Page 7 OASA SpaceKidets - Page 8 What's on Night Sky in April - Page 9-11 Star discovered in closest known orbit around likely black hole - Page 12 SEDNA –THE STOLEN PLANET - Page 13-14 Astronomer Bio OF The Month - Page 15
Credit - Melisa Liu: Member Of The Online Astronomy Society
Written and Edited by Matt Dibble ALMA has been used by astronomers to detect a huge mass of glowing stardust in a galaxy that was seen only when the universe was at 4% of its present age. After the galaxy’s formation it was first observed and currently it is the most distant galaxy in which dust has been detected. This observation is also the most distant detection of oxygen in the universe. These results give new insights into how some of the very first stars are born and their explosive deaths. Nicolas Laporte of the University College London led an international team of astronomers. They have been able to use the Atacama Large Milimeter/submilimeter Array (ALMA) to observe A2744_Yd4, which is the most remote and youngest galaxy to be seen by ALMA. The team were suprised that this youthful galaxy contained such an abundance of interstellar dust. This is dust formed by the deaths of an earlier generation of stars. The ESO’s very large telescope using the X-shooter instrument carried out follow up observations that confirmed the massive distance to AD2744_YD4. The galaxy appears to us now as it was when the universe was only 600 million years old, this was happening during the period when the first stars and galaxies were forming. “Not only is A2744_YD4 the most distant galaxy yet observed by ALMA,” comments Nicolas Laporte, “but the detection of so much dust indicates early supernovae must have already polluted this galaxy.” Cosmic dust is mainly composed of silcon, carbon and aluminium, in grains as small as a millionth of a centimetre across. These chemical elements in the grains are created inside stars and are then scattered across the cosmos when the star dies, in supernova explosions, the final fate of short lived, massive stars This dust is plentiful and is a key building block for the formation of stars, planets and highly comples molecules; however in the early universe - before many of the first generations of stars die out - it was scarce. The observations made of the cosmically dusty galaxy A2744_YD4 are made possible because this galaxy lies behind a massive galaxy cluster called Abell 2744. Because of a phenomenon called gravitational lensing, the cluster acted like a giant cosmic “telescope” to magnify the more distant A2744_YD4 by about 1.8 times, allowing the team to peer far back into the early Universe.
Page 5
The ALMA observations also detected the glowing emission of ionised oxygen from A2744_YD4. This is the most distant, and hence earliest, detection of oxygen in the Universe, surpassing another ALMA result from 2016. The detection of dust in the early Universe provides new information on when the first supernovae exploded and hence the time when the first hot stars bathed the Universe in light. Determining the timing of this “cosmic dawn” is one of the holy grails of modern astronomy, and incredibly can be indirectly probed through the study of early interstellar dust. The team estimates that A2744_YD4 contained an amount of dust equivalent to 6 million times the mass of our Sun, while the galaxy’s total stellar mass — the mass of all its stars — was 2 billion times the mass of our Sun. The team also measured the rate of star formation in A2744_YD4 and found that stars are forming at a rate of 20 solar masses per year — compared to just one solar mass per year in the Milky Way. “This rate is not unusual for such a distant galaxy, but it does shed light on how quickly the dust in A2744_YD4 formed,” explains Richard Ellis (ESO and University College London), a co-author of the study. “Remarkably, the required time is only about 200 million years — so we are witnessing this galaxy shortly after its formation.” This means that significant star formation began approximately 200 million years before the epoch at which the galaxy is being observed. This provides a great opportunity for ALMA to help study the era when the first stars and galaxies “switched on” — the earliest epoch yet probed. Our Sun, our planet and our existence are the products — 13 billion years later — of this first generation of stars. By studying their formation, lives and deaths, we are exploring our origins. “With ALMA, the prospects for performing deeper and more extensive observations of similar galaxies at these early times are very promising,” says Ellis. And Laporte concludes: “Further measurements of this kind offer the exciting prospect of tracing early star formation and the creation of the heavier chemical elements even further back into the early Universe.”
Experiments show Titan lakes may fizz with nitrogen
Written By Andrew Richens
Ever since NASA’s Cassini probe has been imaging the surface of Saturns largest moon, Titan, a mystery has remained unanswered. Titan is the largest moon of Saturn and the only body in the Solar System other than the Earth to clearly display evidence of liquid oceans and lakes. However, the average temperature on the surface of Titan is -179oC. In such extreme environments any water would be frozen as hard as steel. Unlike Earth, Titan’s rivers, lakes and oceans are comprised not of liquid water but of a varying mixture of liquid ethane and methane. Cassini has managed to pierce the dense atmosphere of Titan and imaged the surface in great detail using RADAR. Scientists at NASA though were puzzled by what they saw; small islands would appear and disappear within the liquid oceans. What caused these “magic islands” to behave in such a way has been baffling scientists ever since they were first observed. However, new research conducted at NASA’s Jet Propulsion Laboratory (JPL) in California may at last have an explanation for the mystery; and it has a lot to do with fizzy drinks! Experiments conducted at JPL have shown that methane rain on Titan is able to dissolve large amounts of nitrogen from the atmosphere as the droplets fall. As on Earth, rain on Titan accumulates in rivers, lakes and oceans. Here, the composition of water reservoirs can fluctuate - such as fresh and salt water regions. Similarly, the composition of the reservoirs on Titan fluctuates with respect to their mixtures of ethane and methane. As methane-rich rivers flow into ethane-rich oceans, a complex mix of compositions is formed.
Page 6
The research team at JPL have been able to replicate similar conditions to Titans complex surface within the laboratory – albeit on a much smaller scale! They propose that as the dissolved-nitrogen rich rain falls into reservoirs, the quantity of dissolved nitrogen they can hold varied. Changes in atmospheric pressure due to weather systems or seasonal fluctuations in temperature can result in the dissolved nitrogen being pulled out of its solution. This process is known as exsolution and it results in the release of bubbles. When you undo the cap from a fizzy drinks bottle, the internal pressure rapidly drops and bubbles of dissolved carbondioxide are pulled from the solution. Like a well shaken drinks bottle, the bubble in Titans oceans can also rapidly and dramatically overflow. It is proposed by JPL that this is the cause of the mysterious magic islands on Titan. If they are right, it may have significant implications for future probes visiting the moon. Any probes that float or swim in a liquid reservoir on Titan may be in for an unexpectedly bumpy ride. Propulsion systems such as propellers may, possibly, generate sufficient heat to begin the process of exsolution. The probe could become embedded in a volatile release of nitrogen bubbles, drastically changing the density of the liquid. It really could be sink or swim. On 22nd April 2017 the Cassini space probe will make its final, 127th close flypast of Titan. This time the RADAR will image the northern seas with the task of identifying the brightness of any magic islands. This could provide scientists with additional data to distinguish between the possible presence of bubbles, waves or floating solids. On September 15th 2017, Cassini will end its 20 year mission by destroying itself in Saturns atmosphere; a gallant bid to prevent the possibility of contaminating any life on Titan with microbes from Earth. When the mission finally draws to an end perhaps staff at NASA will celebrate with a bottle of bubbly!
GAS GIANT CLOSE TO FIERY END AS KELT-16B MOVES CLOSER TO ITS STAR Written by Russell Adam Webb
KELT-16b is a gas giant that orbits incredibly close to its star. A year on the planet lasts less than a day on Earth day and this is getting shorter as the planet continues its spiral of death. A new study has found that KELT-16b started its death spiral about 2 billion years ago and shouldn’t last longer than a few hundred thousand years before it is pulled apart by the star. Whilst that might sound like a long time, it is pretty close in a galactic sense. So why bother studying a dying planet? Astronomers believe that studying the scorching skies of KELT-16b can give us a clearer idea of how the atmospheres of exoplanets work. This could, in turn, assist us in our efforts to find potentially habitable exoplanets.
We have found that exoplanets across the galaxy can vary massively. We’ve found rocky planets that have a great deal of potential and we’ve found scorching gas giants that have no chance of life; KELT-16b is most definitely the latter. KELT-16b has been studied by the Kilodegree Extremely Little Telescope (KELT), consisting of a telescope in Arizona and another telescope in South Africa. KELT-16b. they found, is 2.75 times Jupiter’s mass and is 1.4 times as wide as Jupiter; so it’s pretty huge. We have found plenty of examples of exoplanets that lie within their star’s habitable zone, such as Kepler 186F and the Trappist planets. What we can’t yet see is whether these planets have atmospheres, but we are working on that as we speak.
Page 7
KELT-16 is the host star of KELT-16b, and is just a bit bigger than the mass of our Sun. It is located around 1,300 light-years from Earth and strangely enough possesses another star in its system, albeit orbiting very far away (286x the distance between Earth and the Sun. So aside from KELT-16b being pretty far away from us, it’s also pretty hot. It orbits extremely close to its star and temperatures are thought to be around about 4,000 degrees Fahrenheit. Coupled with the incredible doses of radiation the planet will be getting hit with, we won’t be visiting any time soon, or ever in fact. Based on the decaying orbit of KELT-16b, the planet should have once orbited from further away. Gravitational problems were most likely the cause of the planet coming out of alignment and into a death spiral. Within a few hundred thousand years, the planet will be shredded by the gravity of the star. “Most if not all hot Jupiters are likely to end up being tidally disrupted. For KELT-16b in particular, the researchers have precise details on the age of the system and the way in which it evolved, so they can pinpoint the likely timing of the planet’s death — and it is imminent” – Keivan Stassun, study co-author and a researcher at Vanderbilt University in Nashville, Tennessee. “Although we now have many examples of what solar systems can look like, a complete picture requires understanding how often planets don’t survive,” Stassun said. “In other words, we need information about ‘planet mortality’ in order to make complete sense of the planet census.” The fact that KELT-16b orbits so close to its star means that it passes in front of the star more regularly. Astronomers think they will be able to examine light passing through the atmosphere which could tell us much more about its composition and activity. “If its temperature cools enough in going from the dayside to the nightside, KELT-16b may have rain showers of titanium oxide and vanadium oxide at sunset,” Oberst said.
Astronomy Things To See During April 2017 (For UK Observers) Moon: First Quarter: Full: Last Quarter: New:
3rd April 7:39pm 11th April 7:08am 19th April 10:57am 26th April 1:16pm
The Lunar “X” and “V” are visible at around 22:00 UT (23:00 BST) on 3rd April, about 4 hours before the Moon sets. Look along the shadow terminator with binoculars or a telescope and you will see the shapes of the V and X illuminated just on the shadow side, caused by sunlight reflecting off the rims of craters.
Lunar conjunctions & occultations: Note: When the Moon is waxing it is visible in the western sky after sunset. When near Full Moon it is visible most of the night. When it is waning, it is visible in the eastern sky before sunrise 1st April Waxing Crescent Moon lies near Aldebaran th 6 April Waxing Gibbous Moon lies near to Regulus 9th April Waxing Gibbous Moon lies close to Eta Virginis th 10 April Waxing Gibbous Moon lies near to Jupiter and Spica 11th April Full Moon lies near to Spica th 14 April Waning Gibbous Moon occults Gamma Librae (reappearance at 02:00 BST on 14th April) th 15 April Waning Gibbous Moon lies near to Antares th th 16 & 17 April Waning Gibbous Moon lies near to Saturn & Antares 18th April Waning Gibbous Moon lies near to The Teaspoon asterism & Pluto st 21 April Waning Crescent Moon lies near to Delta & Gamma Capricorni 23rd April Waning Crescent Moon lies near to Venus in morning twilight th 28 April Waxing Crescent Moon lies near to Aldebaran & Mars, with daylight occultation of Aldebaran (see below) 30th April Waxing Crescent Moon lies near to Alhena
Planetary Observations: Mercury – reaching greatest eastern elongation on 1st April, look for Mercury low in the west after sunset, where it sets about 2 hours after the Sun. It begins the month at mag 0, but will fade quickly during the month Venus – rising about an hour before the Sun, look for splendid Venus in the east. At mag -4.3 (peak magnitude of -4.6 is reached on 30th April) it will easily be the brightest thing in the eastern sky before dawn. On 23 rd April, Venus lies close to the Waning Crescent Moon, making a lovely photo opportunity Mars – moving from Aries into Taurus this month, look for the mag +1.5 red planet Mars in the west after sunset, where it sets at around 11pm. On 21st April, Mars is close to The Pleiades cluster and on 28th April it lies close to the Waxing Crescent Moon Jupiter – reaching opposition on 7th April, Jupiter is visible all night long this month. Located in Virgo, it will be easy to spot at mag -2.3.Being visible all night, it provides lots of opportunity to view the movement of the 4 Galilean Moons, whose positions are constantly changing. On 5th April, Jupiter lies close to Theta Virginis. On 10th April, it lies close to the Waxing Gibbous Moon Saturn – located in Sagittarius, mag +0.4 Saturn now rises at around 1am. On 16 th & 17th April, Saturn lies close to the Waning Gibbous Moon Neptune – is not observable this month Uranus – is not observable this month Pluto – located in Sagittarius, Pluto rises at around 3:30am and is visible until it is lost in the predawn twilight. On 18th & 19th April the Last Quarter Moon lies close to Pluto. However, at mag +14.2, you will a large telescope to spot it
Ceres – located in Taurus, you may catch a glimpse of Ceres below Mars, low in the west after sunset. It sets at around 10:30pm. At mag +8.6 you will need binoculars or a small telescope to spot it Vesta – located in Gemini this month, Vesta is visible from sunset until it sets at around 3am. On the night of 7 th/8th April, Vesta is in very close conjunction with the mag +5.3 star, 76 Geminorum. Vesta is mag +6.9 you will need binoculars or a telescope to spot it
Other Observations:. Lyrids Meteor Shower – this shower is active from 16th – 25th April. The peak this year takes place between dawn and 4pm BST on 22nd April, so from the UK our best chance of observing meteors is overnight on 21st/22nd April. The hourly rate for this shower is around 18 per hour. The radiant is quite close to Vega and it will get higher through the night until it is almost at the zenith before dawn. With New Moon on 26th April, the Waning Crescent Moon shouldn’t interfere too much with observation this year Daylight Occultation of Aldebaran – if we have transparent skies on 28th April, then see if you can spot Aldebaran disappear behind the Waxing Crescent Moon. Aldebaran will vanish behind the shadow side of the Moon at 7:09pm BST and will reappear from behind the illuminated side at 8:03pm BST. The exact times of this event will vary depending on your location so make sure you start observing 15 – 20 minutes early to ensure that you don’t miss it Binocular Tour – This month’s Sky at Night Binocular Tour by Stephen Tonkin is focused on the sky around Hercules and Corona Borealis. First is probably the most famous object in Hercules, the gorgeous globular cluster M13. This mag 5.8 cluster is naked visible from a dark sky site, but is stunning through 10x 50 binoculars. If you have 15 x 70 binoculars, look for its less famous neighbour M92, which is a mag +6.4 globular cluster. There are 3 more stellar objects to find with 10 x 50 binoculars, the first being 30 Herculis, a semi-regular variable star which is it at the end of its life. Next is the Tau Coronae Borealis Group, which is a long chain of stars of differing colours. The central star is a mag +7.4 triple star which should resolve easily with 10 x 50s. Next is the naked eye optical double star Nu Corona Borealis. Both stars are very similar in colour and magnitude. The final target is for 15 x 70 binoculars, and is HV 38. This is a mag +6.4 white star with a mag +9.7 companion just 30-60 arcseconds away. For full details on how to find these objects, look at this month’s edition of Sky at Night Magazine Deep Sky Tour – This month’s Sky at Night Deep Sky Tour is centred on the area around Hydra and Corvus. There are 3 objects to look for with a small telescope. First is NGC 3242 The Eye Nebula, at mag +8.6 planetary nebula, which is located 1.8 degrees south of Mu Hudrae. Next is NGC 3585, a mag +10 elliptical galaxy. With a 6” telescope it will look oval and uniform, but a 10” telescope will reveal a star-like core. Finally for small telescopes is M68, a mag +8.2 globular cluster. A 6” telescope will reveal a fuzzy circular glow; a 6” telescope will begin to resolve some of the outer stars and a 10” telescope will resolve it fully. If you have a large telescope, look for NGC 3923, another mag +10 elliptical galaxy. Professional images of this galaxy show that it is surrounded by in excess of 40 shells! Next look for NGC 4038/4039 The Antennae Galaxies, which is a pair of interacting galaxies. In small telescopes they appear as a triangular shaped smudge, but a 10” telescope will begin to show lobe-like cores. A 12” will reveal the object fully, showing them as shrimp-like. The final object for large telescopes is NGC 4361 a mag +10 planetary nebula. A 6” telescope will show a hazy round patch but a 10” telescope will resolve the central star. For full details of where to find these objects and how best to see them, pick up the current issue of Sky at Night magazine M64 The Black Eye Galaxy – Astronomy Now’s object of the month is The Black Eye Galaxy, a mag +8.5 spiral galaxy located in Coma Berenices. In binoculars it appears as a faint fuzzy patch, but in order to see the dark patch that gives this galaxy its name, you will need a telescope. Under ideal conditions you may just see the dark patch with a 4” telescope but a 6” or 8” telescope is better and these will also reveal some of the structure in the spiral arms. To image this object, best results will come from LRGB imaging with a mono CCD camera, but colour CCD or DSLR cameras can also give good results under good sky conditions. For more information on how to observe, image or sketch this object, take a look at the current edition of Astronomy Now magazine Constellations Corvus, Crater & Sextans – Astronomy Now’s constellation of the month is actually 3 constellations which form a band underneath Virgo and Leo. They don’t contain a large number of objects but the ones they do contain are quite interesting. Firstly, located within Corvus see if you can spot NGC 4361 a mag +10.5 planetary nebula. It is a challenge to spot visually! Also in Corvus are several galaxies, including NGC 4039 The Antennae Galaxies (see above Deep Sky Tour for more info about this object). Another object which may also be interacting with The Antennae Galaxies is NGC4027, a mag +11.1 galaxy which has a non-symmetrical spiral arm. Another pair of interacting galaxies is NGC 4782 and 4783. At mag +11.2 you will need high magnification to split them. Crater is also full of galaxies, although many of them are very faint. Moving into Sextans, the
stand out object is NGC 3115 The Spindle Galaxy, a mag +10 edge-on galaxy. A second spindle like galaxy in Sextans is NGC 3044, although at mag +12 it is much fainter. There are many faint deep sky challenges in this part of the sky; for more information about all of these objects, take a look at the current edition of Astronomy Now magazine Solar Observations – the lengthening days this month give us more opportunity to observe the Sun. A white light filter will show sunspots, faculae and maybe some granulation. A specialist hydrogen-alpha telescope will show filaments, prominences and if you are lucky you may catch a solar flare in action. Also, if there is a lot of high level cirrus cloud around, keep a look out for solar optical phenomena such as parhelia (sundogs), 22 degree haloes and the various arcs associated with ice haloes SAFETY WARNING: Never attempt to observe or photograph the Sun without the correct equipment. Failure to do so will result in permanent damage to your eyes or even blindness! International Space Station – There are 2 nice evening passes of the ISS most nights for the first half of April. For the exact timings of the passes from your location, visit www.heavens-above.com where you can also check the Iridium flare times for your location
Comets Visible This Month: Comet C/2015 ER61 (PanSTARRS) – at mag +7.3 and brightening, ER61 begins April in Capricornus and moves into Aquarius. You may catch a glimpse of this comet very low in the south east before dawn. On 22 nd April the Waning Crescent Moon lies close, and on the last couple of days of the month it lies close to Neptune. Click here to view the finder chart: http://bit.ly/2kL122C Comet C/2015 V2 Johnson – located in Hercules and mag +8.3 and brightening, this comet becomes visible after sunset in the north east, then it climbs ever higher until it is lost in the morning twilight. On 15th, 16th and 17th April it lies very close to the mag +3.9 star 22 Her. Click here to view the finder chart: http://bit.ly/2kcgAN3 Comet 41P/Tuttle-Giacobini-Kresak – at mag +8 and brightening, this comet begins April in Ursa Major, then rapidly moves through Draco. It is circumpolar so will be visible all night long, and it is predicated to reach peak brightness on 4th April. On 17th April between 00:00 and 03:00 it will pass very close to the mag +2.7 star 14 Dra. During the early hours of the morning of 21st April, it passes very close to the mag +6 star HIP 83138. Click here to view the finder chart: http://bit.ly/2lPvDhP There are several other comets in the mag +11 to +15 range. Details of these can be found in the links below. For up to date information about the fainter comets which are visible, please visit: https://in-the-sky.org/data/comets.php, the BAA Comets Section: https://www.ast.cam.ac.uk/~jds/ or Seiichi Yoshida’s home page: http://www.aerith.net/index.html
NB: All of the information in this sky guide is taken from Night Scenes 2017 by Paul L Money, Philips Stargazing 2017 by Heather Couper and Nigel Henbest, Astronomy Now Magazine, Sky at Night Magazine, Stellarium, the BAA Comets Section website https://www.ast.cam.ac.uk/~jds/, www.inthesky.org and www.heavens-above.com Information collated by Mary McIntyre. For regular updates about the events happening in the sky this month, follow the Nightscenes Monthly Night Sky Facebook page at www.facebook.com/AstrospacePublications
Star discovered in closest known orbit around likely black hole Written and Edited by Matt Dibble It seems that Astronomers have found a star that orbits a distant black hole so close that it whips around it twice an hour. This could be the closest and tightest orbital dance ever witnessed for a black hole and a companion star. NASA’s Chandra X-ray Observatory made the discovery, along with NASA’s NuSTAR and Australia’s Telescope Compact Array (ATCA) CSIRO. The close-in stellar couple — known as a binary — is located in the globular cluster 47 Tucanae, a dense cluster of stars in our galaxy about 14,800 light years from Earth. Astronomers have been observing this binary for many years, and it wasn’t until 2015 that ATCA using radio observations revealed that the pair likely contains a black hole pulling in material from a companion star called a white dwarf. A white dwarf is a low-mass star that has exhausted most of or all of it’s nuclear fuel. New Chandra Data of this system, known as X9, show that it changes in X-ray brightness in the same manner every 28 minutes, which is likely the length of time it takes the companion star to make one complete orbit around the black hole. “This white dwarf is so close to the black hole that material is being pulled away from the star and dumped onto a disk of matter around the black hole before falling in,” said first author Arash Bahramian of the University of Alberta in Edmonton, Canada, and Michigan State University in East Lansing. “Luckily for this star, we don’t think it will follow this path into oblivion, but instead will stay in orbit.” While the White Dwarf does not seem to be in any danger of falling in or being ripped apart by the black hole, its fate is still unclear. “Eventually so much matter may be pulled away from the white dwarf that it ends up only having the mass of a planet,” said co-author Craig Heinke, also of the University of Alberta. “If it keeps losing mass, the white dwarf may completely evaporate.” How did the black hole get such a close companion? It is possible that the black hole smashed into a red giant star, in which the gases from the outer regions of the star was then ejected from the binary.
Page 12
What was then remaining of the Red Giant would then form the white dwarf, which incidentally becomes a binary companion of the black hole. The orbit of the binary would then have shrunk as gravitational waves were emitted, until the black hole started pulling material from the white dwarf. The gravity waves that are produced by the binary have a frequency that is too low to be detected by Laser Interferometer Gravitational-Wave Observatory, LIGO. LIGO has recently detected gravitational waves from merging black holes. Astronomical areas such as X9 could be potentialy detected using gravitational wave observations in space. An alternative explanation for the observations is that the white dwarf is partnered with a neutron star, as opposed to a black hole. The neutron star spins faster as it pulls material from a companion star via a disk, a process that can lead to the neutron star spinning around its axis thousands of times every second. Objects such as transitional millisecond pulsars, have been observed near the end of this spinning up phase. The authors do not favor this possibility as transitional millisecond pulsars have properties not seen in X9, such as extreme variability at X-ray and radio wavelengths. However, they cannot disprove this explanation. “We’re going to watch this binary closely in the future, since we know little about how such an extreme system should behave”, said co-author Vlad Tudor of Curtin University and the International Centre for Radio Astronomy Research in Perth, Australia. “We’re also going to keep studying globular clusters in our galaxy to see if more evidence for very tight black hole binaries can be found.”
Written By Russell Adam Webb
As we learn more about how our solar system came into being, we continue to find anomalies and phenomena in the outer solar system that confound us and force us to rewrite the really old history books. One such anomaly is Sedna; a dwarf planet with an eccentric orbit that some think was stolen from another solar system. The solar system The solar system has a liminal zone; an area that includes the Kuiper Belt and the Oort cloud which stretches over a huge amount of the space between our solar system and the next star. Our first foray into this area was by the New Horizons spacecraft last July and whilst the sheer distances involved means we won’t explore much of the area, the information sent back has forced us into a fundamental rethink about the nature of our existence. Within the Oort cloud and filling the void between us and our stellar neighbors, could be thousands of barren and cold worlds that are pretty tricky to spot. Astronomer Simon Portegies Zwart thinks that much of our solar system might not be ours afterall. “I believe that what is being revealed requires a fundamental rethink of the solar system’s origins, and even of what a solar system is. Put simply, our solar system might not be entirely ours at all.”
The origins of the solar system The creation of our solar system occurred when an outside force, widely believed to be a supernova, made a dust cloud begin to collapse in on itself. The cloud started to spin and the center of this cloud would eventually become the sun.
Page 13
What didn’t go into the sun formed the planets, where rock and other materials fused together and condensed. At the innermost of the system lied Mercury, Venus, Earth, Mars whilst colder temperatures found on the outer reaches created the gas giants: Jupiter, Saturn, Uranus, Neptune. Further still and we reach the area where the temperature was very cold and the particle density fairly low, allowing only smaller, often misshaped, planetesimals to form. This area was called the Edgeworth-Kuiper belt after its discoverers, Kenneth Edgeworth and Gerard Kuiper who first proposed the belt in 1950. We didn’t actually confirm any objects in the belt until 1992, although we have since charted the orbits of over 1000 Kuiper Belt objects. Beyond the Kuiper Belt lies the Oort cloud, also proposed in 1950, by Jan Oort of Leiden Observatory although it had been proposed in 1932 by an Estonian called Ernst Öpik. We should be reminded at this point that the Oort cloud has never actually been seen and even the furthest manmade object from Earth, Voyager 1, will not reach the cloud for another 300 years. We reckon that the gravitational fluctuations from nearby stars and galaxies can cause disturbances in the Oort cloud and often sends comets and rocks towards the sun. One common theory is that some of these comets and icy rocks in the Oort cloud contain the building blocks of DNA and could have first transported the start of life to Earth. Such comets also more than likely wiped out the dinosaurs.
Sedna –The Stolen Planet Between the Oort cloud and the Kuiper belt, Mike Brown of the California Institute of Technology discovered the dwarf planet, Sedna, in 2003. Sedna was only found because its surface is highly reflective; had it been dull, it might never have been found at all. It travels extremely slowly and does not stand out amongst the stars, although it does have a very unusual, elongated orbit. It comes as close as 76 Astronomical Units and as far as 900. We can only see Sedna when it is at its closest. Sedna isn’t alone; we have found many others like Sedna and there could potentially be thousands. The problem with Sedna and its buddies is that they all orbit the same plane and logic dictates that if they’d been kicked out of the Kuiper Belt, it would have been at least a bit more randomized. The same logic dictates that they didn’t come from the Oort cloud. So there are 2 options: The dwarf planets are being kept in line by the gravity of an undiscovered but much talked about planet IX, or they didn’t originate in this system; we stole them. Astronomers, including Simon Portegies Zwart, have been working on massively complex calculations that are trying to work out what happened at the formation of our solar system. We know that stars aren’t born alone; they’re born in clusters, and working out what happened to these clusters can help us determine why the planetesimals at the edge of our solar system behave the way they do.
Page 14
“What emerges is a close brush between our solar system and that of a star almost twice as massive as the sun. Its disc of rubble extended to beyond 160 AU, and it approached at 4.3 kilometres per second to within 230 AU of the sun. In cosmic terms, that is scarily close, although luckily not close enough to have upset the orbits of the solar system’s main planets. For smaller bodies, the jolt was felt as far in as about 40 AU, ripping out any planetesimals beyond that point into interstellar space – in other words, producing the Kuiper cliff (Monthly Notices of the Royal Astronomical Society, vol 453, p 3157).” The calculations show us that other stars had a profound effect on our solar system, especially the outer reaches. It does look as though our young sun took objects from other stars which then ended up in our own region. Sedna is one of the largest of these bodies found so far, although it could be amongst thousands.
Astronomer Biography - Anders Celsius
Anders Celsius was a Swedish astronomer who is known for inventing the Celsius temperature scale. Celsius also built the Uppsala Astronomical Observatory in 1740, the oldest astronomical observatory in Sweden. Early Life and Career: Born in Uppsala, Sweden, Anders Celsius was raised a Lutheran. His father, Nils Celsius, was an astronomy professor. Celsius completed his education in his home town; north of Stockholm. He showed an extraordinary talent in mathematics from childhood. He studied at Uppsala University where, like his father, he joined as a professor of astronomy in 1730. Contributions and Achievements: In his efforts to build a astronomical observatory in Sweden, Celsius visited several of the famous European astronomy sites from 1732 to 1734. At the time, English and French astronomers debated about the actual shape of the earth. To resolve this dispute, teams were sent to the “ends” of the world to assess the precise local positions. Pierre Louis de Maupertuis headed the expedition to the north and Celsius joined as his assistant. The expedition to Lapland, the northernmost part of Sweden, continued from 1736 to 1737. Newton’s theory about the flattening of the earth at the poles was finally confirmed in 1744 after all measurements were taken.
Page 15
Celsius went back to Uppsala after the expedition. He is considered to be the first astronomer to analyze the changes of the earth’s magnetic field at the time of a northern light and assess the brightness of stars with measuring tools. At Uppsala Observatory, Celsius favored the division of the temperature scale of a mercury thermometer at air pressure of 760mm of mercury into 100°C, where 100 was taken as the freezing point and 0 as the boiling point of water. Due to the elaborated fixation of the measuring environment and methods, this account was thought to be more precise compared to that of Gabriel Daniel Fahrenheit and Rene-Antoine Ferchault de Reaumur. Celsius was an avid admirer of the Gregorian calendar, which was adapted in Sweden in 1753, just nine years after his death. “Degree Celsius”, the unit of temperature interval, has been named after this brilliant scientist. Later Life and Death: Celsius became the secretary of the Royal Society of Sciences in Uppsala in 1725 where he remained until his death. He died of tuberculosis in 1744.