In the show this time: we talk to the Vice President at the Society for Maori Astronomy Research and Traditions (SMART), Toa Waaka; Ian rounds up the latest news; and we find out what we can see in the June night sky from Ian Morison and Haritina Mogosanu.
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In the news this month: MACHOS return, Martian tsunamis and an inflatable space station.
A previously disfavoured theory received a boost this month with two articles both proposed that black holes and dark matter could in fact be one and the same.
The superficially plausible idea that the two most famous 'invisible' things in the Universe could in fact be related has existed for a long time, but is not the favourite of cosmologists.
The most widely supported theories for the nature of dark matter -- some matter which feels the force of gravity but does not otherwise interact, and makes up five times more of the Universe than ordinary matter -- involve dark matter being made of some as-yet-undiscovered subatomic particle. These are generally referred to as 'Weakly Interacting Mass Particles' or (WIMPs) and are the subject of many searches, both direct searches seeking to create them in particle colliders and indirect ones seeking to detect the glow given off by the extremely rare interactions of the WIMP particles out in space or here on Earth.
However, an alternative explanation exists in which dark matter is made up of the same stuff as ordinary matter, just in physical states which do not significantly emit or absorb enough light for us to detect.
The dark matter units in these theories are known as MAssive Compact Halo Objects (or MACHOs) and can be made up of things like black holes or brown dwarfs (high mass planets which are not quite big enough to be stars). The idea is that the MACHOs would be massive and abundant enough to look like dark matter, but not emit or absorb enough electromagnetic radiation to be visible to available telescopes.
MACHO theories have existed since the 1980s, but had been disfavoured by a number of observational results in the intervening years. Gravitational microlensing experiments look for the fluctuations in brightness of distant stars caused by the bending of light by individual MACHOs as they pass between us and the star. A number of experiments, including MACHOs, EROS and OGLE, have looked for this effect and failed to find much of it within our galaxy, certainly not enough for there to be sufficient MACHOs to account for dark matter. This can be combined with theoretical calculations as to how disruptive MACHOs would be to binary stars orbiting each other -- large MACHOs would kick binaries out of their mutual orbits. These two together place an upper limit of 20 percent on how much dark matter can be made of MACHOs and tell us that any MACHO must be more than 10 but less than 100 times the mass of the sun, an extremely narrow range by astronomical standards.
However, a new paper published in Physical Review Letters this month latches on to an interesting fact: the black holes which caused the gravitational wave event detected by the LIGO experiment last autumn lay in exactly this mass range. The paper, from astronomers at Johns Hopkins University in the US, pointed this out and also calculated the expected rate at which such mergers should take place, again finding an answer consistent with that estimated by gravitational wave astronomers for the observed merger. We see the effect of dark matter from very early on in the history of the Universe -- such as in the structure of the Cosmic Microwave Background -- at times before stars were formed. This means that if black holes are MACHO dark matter they must be a particular type: primordial black holes.
Primordial Black Holes are not formed by the collapse of a star but by the monolithic collapse of high density regions in the early Universe. Such high density regions were rare, however, but our knowledge of the statistics of fluctuations of the density of matter in the early Universe allowed cosmologist Simeon Bird and colleagues to work out how often Primordial Black Holes of about 30 solar masses would merge, if enough of them existed in our galaxy to be dark matter. Their answer of around five mergers per cubic gigaparsec per year fits nicely within the LIGO estimate of two to fifty three per cubic gigaparsec per year estimated for events like the now-famous GW150914.
Circumstantial evidence possibly, but the scenario is certainly not ruled out.
Some further support for the idea also came from Alexander Kashlinsky, a cosmologist who works at the NASA Goddard-Space-Flight-Center. Kashlinsky also released a paper this month suggesting that thirty solar mass MACHO black holes could also be responsible for the excessive patchiness of the Cosmic Infra-Red and Cosmic X-ray Backgrounds (the CIB and CXB). Observations of these two, widely separated in wavelength and energy, has show that they display the same kind of fluctuations. Kashlinsky points out that one way to emit a lot of light over a very broad range is with a black hole sucking in matter, which is heated by friction in the accretion disk. If Primordial Black Holes were present early in the Universe, they could perform this role and produce the correlated pattern of hot spots seen in the CIB and CXB.
It remains to be seen if the hitherto disfavoured MACHO scenario receives further boosts from gravitational wave observations. As more and more black hole mergers are observed we will come to know the true mass distribution and merger rates of the objects, finding whether or not they are consistent with the properties of MACHO dark matter.
Also in the news this month, new observations of the planet Mars have been suggested to show evidence of a tsunami on the red planet some 3.4 billion years ago.
The subject of liquid water on Mars today remains a controversial subject, but the idea that it existed on the surface billions of years ago has grown steadily more accepted since the Mariner 9 probe landed on the planet in 1971.
The new research published this month in the journal Science Reports dealt with the subject of the impact of a meteoroid on the surface of the huge ocean which it has been proposed used to cover much of the Northern Martian hemisphere. Whilst evidence of the coastline of the Northern ocean is visible in many places, in others it appears to disappear. The work by a group of researchers led by Alexis Rodriguez of the Planetary Science Institute in Tucson, Arizona, suggests that at least some of these missing portions of coastline were wiped out by massive tsunamis caused by meteoroid impacts in the distant past.
By using data from a number of Mars observation satellites, Rodriguez and collaborators saw geological formations corresponding to the rush of water from the tsunami inland, covering an area the size of Texas (or Turkey). Also visible is evidence of the retreat of this water, in smaller channels cut by the trickle of water back into the ocean. The tsunami would have been up to 120 metres high and consist of the chilly, salty, but liquid water present on Mars at the time.
Further evidence was also found for a second of these mega-tsunami a few million years later. The apparent presence of a second sea level, much lower than the first in the region suggests that Mars' climate grew much colder in the intervening time, meaning this time the tsunami consisted of a slow-moving slush of water ice. This tsunami also apparently never receded, instead freezing in place on the shore, leaving behind large visible icy deposits.
Similar shoreline lobe structures can also be seen from tsunamis here on Earth, as can analogues of the isolated pockets of water left behind by the tsunami, which may have been ideal places for life to evolve. Some of the team involved in the work hope to travel to Tibet this year to investigate life in similar lakes.
And finally, astronauts and cosmonauts aboard the International Space Station were provided with extra working space this month with the successful addition of a new, inflatable attachment to the station.
The Bigelow Expandable Activity Module (or BEAM) provides an extra car-sized space for those on the ISS, but shrinks to to only a fifth of that volume for launch and transportation -- an extremely useful property to help reduce the huge expense of space travel. BEAM consists of flexible Kevlar-like ring supports with multiple layers of fabric and polymer foam in between.
After an aborted attempt to inflate the room last month, the procedure went smoothly this time, with NASA astronaut Jeff Williams reporting an expected -- but probably annoying -- popcorn-like sound consistently over the seven-hour inflation of the module. This is the first time such an inflatable module has been used for human habitation, and will hopefully pave the way for more, cheaper biomes both in Earth orbit or on the moon.
Interview with Toa Waaka
This month is the month of Matariki, the Maori New Year, a time of reflection, recognition and respect which is marked by the rising of the Pleiades. To mark this special time for our friends in Aoteroa, New Zealand, it is our privelige to share an interview between our antipodean astrobiologist and Night Sky South correspondant, Haritina Mogosanu, and Toa Waaka, the the Maori Strategy Project Manager for Otago University Wellington and Vice President of the Society for Maori Astronomy Research and Traditions (SMART).
Astronomy is an important part of Maori culture, as is immediately testified to by many of their stories and legends, but as Toa Waaka explains, its significance for the Maori people runs much deeper, manifesting itself even in the fundamentals of the Maori language. As early as 3000BC the Maori people were expanding across the Pacific Ocean in canoes, using the stars of the night sky as a navigational tool.
Working with, among others, the first Maori Astrophysicist, Dr. Pauline Harris, and others, Toa has been working towards preserving and sharing Maori scientific knowledge, long buried in geanealogical charts. Toa speaks to us about how this process: about the significance of Matariki; about how it has shaped Maori traditions; about those who were lost to the night; and about the ways migration has influenced different dialects and aspects of Maori culture on islands all over the Pacific Ocean, from New Zealand, to the Easter Islands, to Hawai'i. The interview begins with a Karakia: the Karakia of Creation.
The Night Sky
Ian Morison tells us what we can see in the northern hemisphere night sky during June 2016.
Highlights of the month
June 1st - 8th: Mars at its best for 11 years.
Mars reaches opposition - that is when the Earth lies between the Sun and Mars and when it was be approximately due south at midnight (UT) or 1am (BST) - on the 22nd of May, so it will be visible for most of the hours of darkness. However, it was actually be closest to the Earth and so having its greatest angular size of 18.6 arc seconds some 8 days later on the 30th of May. The angular size at closest approach varies due to the ellipticity of the orbit of Mars (and to a far lesser extent to that of the Earth) and will reach 26 arc seconds during 25,695 AD. At closest approach in 2003, Mars reached an angular size of 25.1 arc seconds, its largest angular diameter for 60,000 years. In July 2018 it will reach 24.2 arcseconds across but for both this opposition and that in 2018, Mars will be very low in the ecliptic and hence at low elevation so that the atmosphere will limit our views of the red (actually salmon pink) planet. Happily, it will be higher in the sky at the opposition of 2020.
To find what should be visible at any time, one can use the Sky & Telescope application.
June - The best month to observe Saturn.
Saturn reaches opposition on the 3rd of June, so is now due south and highest in the sky around midnight (UT) or 1am (BST).
It lies in the southern part of Ophiuchus 7 degrees up and to the left of the orange star Antares in Scorpius.
Held steady, binoculars should enable you to see Saturn's brightest moon, Titan, at magnitude 8.2. A small telescope will show the rings with magnifications of x25 or more and one of 6-8 inches aperture with a magnification of ~x200 coupled with a night of good 'seeing' (when the atmosphere is calm) will show Saturn and its beautiful ring system in its full glory.
As Saturn rotates quickly with a day of just 10 and a half hours, its equator bulges slightly and so it appears a little 'squashed'. Like Jupiter, it does show belts but their colours are muted in comparison.
The thing that makes Saturn stand out is, of course, its ring system. The two outermost rings, A and B, are separated by a gap called Cassini's Division which should be visible in a telescope of 4 or more inches aperture if seeing conditions are good. Lying within the B ring, but far less bright and difficult to spot, is the C or Crepe Ring.
Due to the orientation of Saturn's rotation axis of 27 degrees with respect to the plane of the solar system, the orientation of the rings as seen by us changes as it orbits the Sun and twice each orbit they lie edge on to us and so can hardly be seen. This last happened in 2009 and they are now opening out, currently at an angle of 26 degrees to the line of sight. The rings will continue to open out until May 2017 and then narrow until March 2025 when they will appear edge-on again.
June - Find the globular cluster in Hercules and spot the "Double-double" in Lyra
There are two very nice objects to spot with binoculars in the eastern sky well after dark this month. Two thirds of the way up the right hand side of the 4 stars that make up the "keystone" in the constellation Hercules is M13, the best globular cluster visible in the northern sky. Just to the left of the bright star Vega in Lyra is the multiple star system Epsilon Lyrae often called the double-double. With binoculars a binary star is seen but, when observed with a telescope, each of these two stars is revealed to be a double star - hence the name!
June 3rd just before dawn: Mercury close to a very thin crescent Moon.
Some 30 or so minutes before dawn on the 3rd of June and given a low eastern horizon and clear skies it would be possible to spot Mercury, shining at magnitude +0.7 just 3 degrees to the left of a very thin crescent Moon.
Late June: A very good time to spot Noctilucent Clouds!
Noctilucent clouds, also known as polar mesospheric clouds, are most commonly seen in the deep twilight towards the north from our latitude. They are the highest clouds in the atmosphere at heights of around 80 km or 50 miles. Normally too faint to be seen, they are visible when illuminated by sunlight from below the northern horizon whilst the lower parts of the atmosphere are in shadow. They are not fully understood and are increasing in frequency, brightness and extent; some think that this might be due to climate change! So on a clear dark night as light is draining from the north western sky long after sunset take a look towards the north and you might just spot them!
Night of June 15 to 16th when fully dark: The Lyrid Meteor Shower
The June Lyrid meteor shower reaches its peak on the night of the the 15th/16th with a rate at the zenith of ~8 meteors per hour. This is not many and, as full Moon on the 20th is approaching, it may be hard to spot one. The radiant is very close to the star Vega. Many more meteors were seen from the shower in the late 1960's but the peak hourly rate has dropped off markedly since then. If clear, it may still be worth aiming to see if you can spot one.
June 14th and 15th: The Alpine Valley
These are two good nights to observe an interesting feature on the Moon if you have a small telescope. Close to the limb (on the 14th) is the Apennine mountain chain that marks the edge of Mare Imbrium. Towards the upper end you should see the cleft across them called the Alpine valley. It is about 7 miles wide and 79 miles long. As shown in the image a thin rill runs along its length which is quite a challenge to observe. Over the next two nights the dark crater Plato and the young crater Copernicus will come into view. This is a very interesting region of the Moon!
Observe the International Space Station
Use the link below to find when the space station will be visible in the next few days. In general, the space station can be seen either in the hour or so before dawn or the hour or so after sunset - this is because it is dark and yet the Sun is not too far below the horizon so that it can light up the space station. As the orbit only just gets up the the latitude of the UK it will usually be seen to the south, and is only visible for a minute or so at each sighting. Note that as it is in low-earth orbit the sighting details vary quite considerably across the UK. The NASA website linked to below gives details for several cities in the UK. (Across the world too for foreign visitors to this web page.)
Note: I observed the ISS three times recently and was amazed as to how bright it has become.
Find details of sighting possibilities from your location from: Location Index
See where the space station is now: Current Position
Jupiter is now past its best, but still stands out in the southwest and west at nightfall. Its brightness falls slightly from magnitude -2.1 to -1.9 whilst its angular size drops from 37 to 34 arc seconds. Jupiter is now in the lower part of Leo, slowly moving eastwards towards Virgo which it will enter in August. Our best views of the planet are now past for this apparition but, with a small telescope one may well be able to see the equatorial bands in the atmosphere and up to four of the Galilean moons as they weave their way around it.
Saturn reaches opposition - that is when it be approximately due south at midnight (UT) or 1 am (BST) - on June 3rd, and so will be visible in the southeast at nightfall and will not set until dawn the following morning. It is moving slowly in retrograde motion in the lower part of Ophiuchus but close to the the fan of three stars that makes up the head of Scorpius and about 7 degrees up and to the left of Antares. This is a good time to observe Saturn whose globe is ~18 arcseconds across and whose rings span some 41 arcseconds across. They make a beautiful sight as are tilted 26 degrees from the line of sight - almost as open as they can be. It is sad that Saturn is now in a low part of the ecliptic and will only reach an elevation of 20 degrees when due south. I was able recently able to view it through a 16" telescope from a latitude of +29 in the Sahara Desert and it was stunning - perhaps a trip to the southern hemisphere is called for!
See highlight above.
Mercury is a pre-dawn object for the first week or so of the month best seen about 30-45 minutes before sunrise. It starts the month at magnitude +0.8 with an angular size of 9 arc seconds. This increases to magnitude zero by the 11th - perhaps the best time to view - with the angular size having dropped to 7.3 arc seconds. It will then be only ~7 degrees above the horizon so still be difficult to spot and a good low horizon in the east will be needed.
See highlight above.
Mars reaches opposition on May 22nd and came closest to the Earth for 11 years on the 30th. So June is a second excellent month to observe the salmon-pink planet. Mars starts the month at magnitude -2, drops to to -1.7 by the 16th and -1.4 by month's end. At the same time the angular size drops from 18.6 to 16.4 arc seconds. Mars moves in retrograde motion in Libra until the 30th when it resumes its eastwards path through the stars moving back towards Saturn.
See highlight above.
Venus reaches superior conjunction (that is directly behind the Sun) on June 6th and so cannot be observed this month.
Haritina Mogosanu from the Carter Observatory in New Zealand tells us about the southern hemisphere night sky during June 2016.
Clear skies from from the top of Mount Victoria, in Wellington and greetings from Space at Carter Observatory in Aotearoa New Zealand.
My name is Haritina Mogosanu and tonight I am your starryteller from the Southern Hemisphere.
Top of Mount Victoria here in Wellington New Zealand is where I always felt on top of the world. To the South, I can sense Antarctica's frozen breath. To the North, I see glimpses of my faraway home-beacons: Andromeda, Arcturus and Vega. They are like a safety net. Something familiar. East and West are obviously looking weird – the Sun moves from right to left in the sky in the Southern Hemisphere, leaning towards North. In the Northern Hemisphere the Sun still goes from east to west but moving from left to right leaning towards South. So as I said before in previous episodes of the Jodcast, the shadow in the afternoon here looks just like the shadow of the morning in the Northern Hemisphere.
Being in the city of Wellington makes me feel grateful for the courage to leave my safe shore back home to seek my diamonds in the sky. Wellington at night glows like a net of diamonds itself. And it's the best sky that probably any capital of the world has ever seen. As for the star lore that people brought here… well… it's the most spectacular by far!
Which brings me to the month of June when here in New Zealand we celebrate the Maori New Year, Matariki.
Matariki is a lunar celebration. As you do with the Polynesian cultures, not everyone does everything in the same way but some tribes celebrate the new year, te Tau Hou, by observing the heliacal rising of the Pleiades, M 45, or as the cluster is called at this time of the year by Maori, Matariki. Some tribes use the star called Puanga (or Rigel). But no matter what marker they use, they observe its heliacal rising (that is before the Sun) just after the first new Moon that occurs after the longest night. I feel compelled to mention the fact that they only call the cluster Matariki at this time of the year, in the morning. The same stars appear in the asterism of Te Waka O Tama Rereti, present on the November's night sky and also three months later when they make Te Tawhiti, the shining one. I spoke about these asterism in Jodcast episodes from previous months. But nobody calls them Matariki then. The small group of stars are just part of something bigger. This was quite a discovery for me because in the western skylore, asterisms have only one name no matter what time of the year it is. As I was going to discover later, not only Matariki - The Pleiades are part of shapeshifting stories in the sky but also most of Maori legends include constellations that are only seasonal.
Back to the new year, here in Aotearoa New Zealand, the beautiful cluster of MataAriki, the eye of the God, rises before the Sun to mark the new year just after the new Moon's occurrence. The cluster will start being visible towards the middle of the month, that is if you wake up very early in the morning, just before sunrise, and look east. However, the first new Moon of June is on the 5th, but the cluster will be too low on the horizon to see. Counting the fact that Wellington's landscape is quite hilly, and the fact that the Maori tohunga tatai arorangi (astronomers) had to see the cluster visually before they could declare the new year, that positions, realistically, the period of Matariki, just after the longest night of the year, the winter solstice, which is also occurring in June. The next new Moon after the 5th of June is on 4th of July. Technically, the period of the new year lasts for about a month from one new Moon to the other and for some tribes was the time in between the years, when everything would reset and people would visit the year that has passed and think ahead to the year that would follow. You can hear more about Matariki and Maori astronomy in this month's interview that I took with Toa Waaka, vice chair of the Society for Maori Astronomy, Research and Traditions.
In Wellington this year Space Place at Carter Observatory has organised two dawn ceremonies. The first is on Saturday the 18th of June and the second is on the 22nd of June. That is of course providing the weather stays clear. You can always check our website for more details. And also of course, this month we will be incorporating Maori astronomy in our talks. The dawn ceremony will be held on top of Mount Victoria, where we go every year and it will start from 5:30 AM. Feel free to come along - there will be hot chocolate!
Back to our evening sky, bright planets light up the sky along with the brightest stars once again. Golden Jupiter appears midway up the north sky soon after sunset. Orange Mars is due east. Jupiter and Mars are similar in brightness but you can tell them apart by colour and position. Cream-coloured Saturn is below and to the right of Mars and fainter, directly below orange Antares, the brightest star in Scorpio. Saturn is at opposition on the 3rd of June, rising close to the time of sunset and setting near the time the Sun rises. The Moon will be near Jupiter on the 11th and 12th and passing by the Mars-Saturn region on the 17th to 19th.
Low in the west at dusk Sirius, Takurua, the brightest true star, twinkles blue, sets around 9 pm mid-month. It will appear again in the morning sky to help point at Matariki. Canopus Atutahi, the chief of the Maori stars and the second brightest star, is in the southwest. Atutahi is a chief because it can always be seen in the sky, it is a 'circumpolar' star: one that never sets but goes around in circles.
Sirius/ Takurua is the Zenith star of Tahiti and it was used so by the Polynesians. Sirius appears bright both because it is 20 times brighter than the sun, and because it is relatively close at nine light years. Canopus, the second brightest star, is higher in the southwest sky, circling lower into the south later on. Canopus is around three hundred light years away and 13,000 times brighter than the sun but almost of the same spectral type as the Sun. I fell in love with Canopus when I found out that is on board the Voyagers, as a positioning aid. In fact many starcraft carry a special camera called Canopus Star Tracker. Before the magnetic compasses, Canopus was also considered the south star and navigation was made based on its position. And of course Canopus was the navigator of Argo Navis, and is part of the modern constellation of Carina, which used to be part of Argo Navis.
Opposite Canopus, Arcturus is a lone bright star in the northeast, in the constellation of Bootes. Polynesians call it Hokuleʻa, the "Star of Joy". Arcturus is the Zenith star of the Hawaiian islands. Its orange light often twinkles red and green when it is low in the sky. It sets in the northwest in the morning hours.
Crux, the Southern Cross, is south of the zenith. Beside it and brighter are Beta and Alpha
Centauri, often called 'The Pointers' because they point at Crux. Alpha Centauri is the closest naked-eye star, 4.3 light years away. Beta Centauri and many of the stars in Crux are hot, extremely bright blue-giant stars hundreds of light years away. They are members of a group of stars that formed together then scattered. The group is called the Scorpio-Centaurus Association.
Antares or Rehua is marking the scorpion's heart. In Maori this is the asterism of Manaia Ki Te Rangi, the guardian of the heavens, which one of the three names that Scorpius has here. More so, the entire asterism of Scorpius is the the zenith asterism of Aotearoa, the land of the long white cloud. This land is so big compared to the other Pacific islands that it needs an entire asterism to mark its position in the sky.
Rehua is a red giant star: 600 light years away and 19 000 times brighter than the sun. Red giants are much bigger than the sun but much cooler, hence the orange-red colour. Though hundreds of times bigger than the Sun, Antares is only about 20 times the Sun's mass or weight. Most of the star's mass is in its hot dense core. The rest of the star is thin gas.
Red giants are dying stars, wringing the last of the thermo-nuclear energy from their cores. Antares will end in a spectacular supernova explosion in a few million years.
Below Scorpius is Sagittarius, it's brighter stars making 'the British teapot'.
The Milky Way is brightest and broadest in the southeast toward Scorpius and Sagittarius. It remains bright but narrower through Crux and Carina then fades in the western sky. The Milky Way is our edgewise view of the galaxy. The thick hub of the galaxy, 30,000 light years away, is in Sagittarius. Behold the Milky Way Kiwi, a dark patch in the sky resembling a kiwi bird, holding on its head just like a crown, the galactic center. A scan along the Milky Way with binoculars will find many clusters of stars and some glowing gas clouds. Relatively nearby dark clouds of dust and gas dim the light of distant stars in the Milky Way. They look like holes and slots in the Milky Way. There is a well-known dark cloud called The Coalsack by the Southern Cross. Maori call it te Patiki, the flounder. It is around 600 light years away. The dust, more like smoke particles in size, comes off old red stars. These clouds eventually coalesce into new stars.
Then, there are the Clouds of Magellan, LMC and SMC, in the lower southern sky, are luminous patches easily seen by eye in a dark sky. They are two small galaxies about 160,000 and 200,000 light years away. The Large Cloud is about 5 percent the mass of the Milky Way; the Small Cloud is about 3 percent.
Mercury is in the northeast dawn sky. At the beginning of the month it rises two hours before the sun. It sinks lower through the month. Around the 17th it will be left of orange Aldebaran. Further left of Mercury will be the Pleiades/Matariki star cluster just appearing in the dawn twilight. To see it you will have to learn how to count in Maori: First locate Atutahi - in the dawn sky it will floating low in the southeastern sky. Tahi in Maori means One. Then follow along the Milky Way, you will see blue Takurua, Sirius. Rua means two in Maori. Then on the same line, when they will get parallel with the horizon, the three stars from Orion's belt, Tautoru. In Maori, toru means three. Tahi, Rua, Toru. One, two, three. If you join Takurua with Tautoru and extend the line toward north, just passing Taumata Kuku (the Hyades and red Aldebaran) that look like a triangle, following just a little bit more towards north you will find Matariki. At 444 light years away from Earth, Matariki stars are hot, young and blue and with the naked eye you can see six of them, with a pair of binoculars you can see many more. The best view is with a smaller magnification binoculars as they can fit more stars in the field of view. The Pleiades, or Messier 45 are about 100 million years old, being born just after the dinosaurs went extinct on Earth. The light from the Pleiades - Matariki left the cluster almost in the same time as Galileo was pointing his telescope to the heavens.
This concludes our Jodcast for June 2016 at Space Place at Carter Observatory. May you enjoy clear and dark skies so that you can see the stars and always remember that we are made of the same star dust as they are! Kia Kaha and clear skies from the Space Place at Carter Observatory in Aotearoa New Zealand and since the new year will start soon, Nga Mihi o Te Tau Hou.
Odds and Ends
The elusive Planet 9 which has so far only showed up in computer simulations, may have been captured by the Sun from one of its siblings. Stars are born in groups and over time, these groups become separated by their relative motions around the Galactic centre. The Pleiades is an example of a group of young stars that are still together in an open cluster. The Hyades is an older analogue of the Pleiades which contains more mature stars with much greater separations. With still older stars it becomes much more difficult to find a star's old cluster mates unless they all have common proper motions, like the Ursa Major Moving Group. Anyway - Planet 9, postulated to exist due to its resolution of some strange Solar System dynamics, such as the eccentricity of Sedna's orbit may not have been born in the Sun's proto-planetary disk but stolen from a sibling star during the Sun's youth. This capture would have resulted in an alien, highly inclined and eccentric planet in the Solar System, which perturbs the orbits of outer Solar System bodies such as Sedna. This means that our nearest exoplanet may well be in our own back yard and if it exists, it wouldn't be too difficult to send something there to explore.
On the 10th of May, NASA released a paper announcing the discovery of 1284 new exoplanets using data from Kepler, doubling the telescope's haul so far, and meaning Kepler has now discovered more than 2/3 of all known exoplanets. The new results are particularly interesting, as they have been produced using a new automated system using Python code, called 'vespa'. This was tested on older Kepler data and identified planets we already know about with >99 percent accuracy, so the mission scientists are very confident in its abilities. The new identifications were made by scanning the entire data catalog that Kepler has produced so far, including data on many stars that had previously been tested but for which no positive planet identifications had been made. Vespa and software like it likely are going to be a very important tools for astronomers going forward, as the sheer volume of data coming from Kepler and future missions make it nearly impossible to search for exoplanet candidates using traditional manual methods. 550 of these newly discovered planets may be rocky (based on their mass), and it has also added 9 of these to what one of the mission scientists calls the "exoplanet hall of fame", meaning objects with a likely rocky composition and orbit in thier stars habitable zone. This brings the total number of these "hospitable" worlds to 21. One astronomer has concluded that about 24 percent of the stars harbour potentially habitable planets, although it is worth noting that there are many more factors that can affect practical habitability. Kepler launched in 2009, but suffered equipment failure in 2013, meaning its orientation can only be controlled in two dimensions. However, the telescope is still useful, as NASA have successfully tested a plan to point the telescope using the sun's radiation pressure as a stabiliser. It is unknown what caused the probe to go into emergency mode in April this year, but it was likely a software problem rather than hardware failure, as it has been operating without issue since. It is hoped that the incredibly successful Kepler will continue providing data for a few more years.
Yale University Professor turns to Kickstarter to fund further research on what has been dubbed the weirdest star in the galaxy. Professor Tabetha Boyajian after whom the star known as Tabby's star is named was first observed using NASA's Kepler Telescope. The Kepler telescope began observations in 2009 in order to search for exoplanets by searching for dips in the brightness of stars. An online public database was created known as Planet Hunters where many amateur astronomers took to the search identifying light curves and possible transits. The usual dips in the brightness of a star, as a result of an exoplanet's orbit, are on the order of about 1 percent of the stars brightness. However this public search led to the discovery that Tabby's star experienced aperiodic dips in brightness on the order of 20 percent and 15 percent. There were many hypotheses about the possible reasons for these dips including planets, dust clouds, asteroid belts, and comets which were presented in a paper written by Professor Tabetha Boyajian and her colleagues titled "Where's the Flux" in 2015. Another explanation proposed came from Jason Wright an astronomer from Penn State who suggested that the dips in brightness could be the result of an artificial alien megastructure, known as a Dyson Sphere a hypothetical megastructure that would encompass a star to capture all of its energy thus causing dips in its brightness. The SETI Institute's Allen Telescope Array (ATA) was directed at the star in order to search for radio waves emanating from the star which would support the idea of alien made structures, however no evidence was discovered. Perhaps some elusive aliens had moved on, or maybe a more natural explanation is the key, who knows...? In the hope of further understanding what is occurring Professor Boyajian hopes to procure funding in order to observe the star at multiple wavelengths in the hope of determining what elements the objects causing the dips in brightness are composed of. To do this she has turned to the public for help once again, looking to raise $100,000 by the 17th of June 2016 on Kickstarter.
|Interview:||Toa Waaka and Haritina Mogosanu|
|Night sky:||Ian Morison and Haritina Mogosanu|
|Presenters:||Benjamin Shaw, James Bamber, and Nialh McCallum|
|Editors:||Benjamin Shaw, Monique Henson, Haritina Mogosanu, and Charlie Walker|
|Segment Voice:||Kerry Hebden|
|Website:||Charlie Walker, Saarah Nakhuda and Stuart Lowe|
|Cover art:||Matariki - The Eyes of God, or The Little Eyes, are the constellation of the Pleiades as seen from the Southern Hemisphere. CREDIT: NZ Maori Tourism|