Article written by: Heather Alexander, Education officer
At the Armagh Observatory and Planetarium we have been having a look at all the things that are going to happen throughout the year and trying to select some of the events that we are most looking forward to. Needless to say this was a hard task, but we have managed to come up with a top 10 list for you!
Before their mission to the moon. The Apollo 11 crew were in quarantine to make sure they didn’t get sick. During this time they signed lots of photos and cards to act as life insurance for family. Credit: NASA.
Happy 50th Anniversary Apollo 11
As you may already know, humans have landed and walked on the Moon. This year marks the 50th Anniversary of the momentous occasion. Neil Armstrong and Buzz Aldrin made history in July 1969, and will forever be known as the first men to walk on the Moon. Michael Collins, the third man on the mission, also made history as the first person to fly solo around the Moon. This anniversary will be celebrated around the world, and we here at the Armagh Observatory and Planetarium will be doing the same. We have numerous activities organised so keep an eye out on our website and Facebook page for more details.
Happy 50th Anniversary Bovedy Meteorite
This is an event that we are especially looking forward to! In Northern Ireland in 1969, a meteorite fell. It was the first meteorite where the sound of its passage through the atmosphere was recorded, and it split in two. One piece landed in a field in Bovedy and the other half crash landed through the roof of a police store station in Sprucefield in Lisburn. We have half of this meteorite in our collection and we plan to have some events on both the 13th and 25th April to mark this historic event. This will include a special presentation from artist Noel Connor who remembers seeing the Bovedy as a school boy in Belfast. He has created a special Dome show around memories of that day. Keep an eye on our Facebook page and our website for more information.
A Super Blood Moon! Sounds like something from a horror film, but it’s just the moon passing into the Earth’s shadow! Credit: NASA
Lunar Eclipse January 2019
On 21st January there will be a total lunar eclipse visible in Northern Ireland. This is very exciting, and will be your last chance to see an eclipse like this in Ireland for a decade. We’ve already written several blog articles about this, check them out HERE and HERE. A Lunar Eclipse occurs when the Moon passes into the Earth’s Shadow, turning it a ghostly red colour! We have an event planned for the morning of the eclipse, with different talks and presentations and also viewing through our historic Grubb Telescope!
Hayabusa2 will take sample from Asteroid Ryugu and start its return to Earth this year (2019) Credit: Go Miyazaki
We’ve been keeping an eye on the Japanese Hayabusa2 mission for some time now, and this year it will final take sample from its selected asteroid! Hayabusa2 was launched on 3 December 2014 and rendezvoused with near-Earth asteroid 162173 Ryugu on 27 June 2018. In September and October of 2018 Hayabusa2 successfully landed 2 rovers on the surface of Ryugu. The date is yet to be determined but it is believed that some time in February of this year a sample will be taken from Ryugu and then in December Hayabusa2 will make its journey back towards Earth!
Picture of CHEOPS taken in September 2018. Credit: ESA–A. Conigli
The Characterising Exoplanets Satellite, or CHEOPS, is a European Space Agency project. As stated on the ESA website, CHEOPS “will observe individual bright stars that are known to host exoplanets, in particular, those in the Earth-to-Neptune size range. By targeting known planets, CHEOPS will know exactly when and where to point to catch the exoplanet as it transits across the disk of its host star.” The launch date is expected to be between 15th October and 14th November 2019. This will be an exciting event for all those involved in the creation of CHEOPS and we can’t wait to see the data that this satellite will provide for the astronomical community!
Chandrayaan-2 Credit: GSAT-4/ISRO
Chandrayaan-2 will see ISRO (Indian Space Research Organisation) make its first attempt at a soft landing on the Moon! This is scheduled to happen in early 2019, with estimated dates between late January to late February and April. More information will be available closer to the time, once all the relevant tests and checks have been carried out. The Chandrayaan-2 will consist of a Lunar Orbiter, Lander and Rover, all developed by India. We can’t wait to hear and see more about this mission, and after the success of China’s Chang-e 4 at the start of January, we have high hopes for Chandrayaan-2.
Spektr-RG is a Russian and German made high energy astrophysics space observatory, with a planned launch for March 2019. It will specialise in X-Ray astronomy and will spend 4 years conducting an X-Ray Survey. This survey will be conducted by the primary instrument, the eROSITA. and it will hopefully detect new clusters of galaxies and active galactic nuclei. The second instrument is the ART-XC and it is an X-Ray telescope.
Credit: Loren Roberts
After the huge success of Change-4, the Chinese have been developing Chang-e 5 and it is also a Lunar Lander, but also a sample return vehicle. It will be China’s first sample return mission and is set for launch in December 2019. It is aiming to return at least 2kg of lunar soil back to the Earth.
The Parker Solar Probe
Back in August 2018, the Parker Solar Probe was launched, and its mission is to unlock the mysteries of the Sun’s atmosphere. 2019 will see the probe reach the second and third perihelion. You might be wondering, what is a perihelion? The perihelion is the point in the orbit of a planet, asteroid, comet or satellite that is nearest to the Sun. It is the opposite of aphelion, which is the point farthest from the Sun. The second perihelion will be reached on 4th April, and the third perihelion will be reached on 1st September. The probe also gets gravity assists from the planet Venus. The second gravity assist from Venus will occur on 26th December 2019.
This image of Mercury passing in front of the sun was captured on Nov. 8, 2006 by the Solar Optical Telescope, one of three primary instruments on the Hinode spacecraft. Image credit: Hinode JAXA/NASA/PPARC
Transit of Mercury
A rare transit of
Mercury will occur on 11th November 2019. This means that the planet
Mercury will move directly between the Earth and the Sun, and those with proper
telescopes that have solar filters applied will be able to observe it. Weather permitting,
we will be able to observe this phenomenon here in Armagh in Northern Ireland!
This is a rare occurrence and the next transit of Mercury is not set to happen
until the year 2039.
As pointed out in Helen’s January edition of the Monthly Night Sky, if skies are clear on the morning of 21st January 2019, sky-watchers will witness a rare total eclipse of the Moon. This will be the last opportunity to view a total lunar eclipse from the British Isles for three-and-a-half years, until 16 May 2022. However, even on that occasion, as seen from Northern Ireland the Moon sets before the end of totality. Indeed, the next total lunar eclipse visible in its entirety from NI will not be until the year 2029.
The partial, or main, phase of the eclipse begins at 0334 GMT when the Moon is 40 degrees above the horizon in a West South-West direction. Totality begins at 0441 GMT at 31 degrees altitude due West and ends at 0543, with the Moon now lying in a direction slightly North of West at an altitude of 23 degrees. Our natural satellite then exits the Earth’s umbra completely at 0651 GMT and at an altitude of 13 degrees above the horizon.
The circumstances of this eclipse are very nearly perfect for observers in NW Europe. In addition to the British Isles, the eclipse is visible in its entirety from the Americas, and in Europe from Portugal and Norway as well as parts of Spain, France, Finland and Sweden. Observers in other parts of Europe will see the Moon set before the end of the penumbral phase, though most of the continent will be able to view the event up to the end of totality.
From the British Isles, the partial & penumbral phases following totality occur at relatively low altitude and provide a wide range of photo opportunities, with a partially-eclipsed Moon silhouetted against buildings, landmarks and other suitably photogenic background scenery. Sunrise occurs at 08:30 GMT, approximately one hour after the eclipse ends.
Although being up early on a Monday morning may not sound an attractive proposition, the upcoming eclipse will be the last one visible from these parts for quite a while. Total lunar eclipses visible from Northern Ireland will take place on 16 May 2022, on 14 March & 7 September 2025, on New Year’s Eve 2028 and on 26th June 2029. However, on those occasions the Moon is very close to the horizon and difficult to observe during the total phase. Indeed, the next total eclipse visible from the British Isles in its entirety will not occur until the 20th December 2029, more than ten years hence.
Total eclipse of the Moon, as seen from Armagh on 2015 September 28. Digital images recorded by observers Ruxandra Toma and James Finnegan, and compiled with assistance from Onur Satir.
To view the totally-eclipsed Moon, given suitably clear skies one should begin observing before 05:45 GMT on the morning of the 21st. Those finding themselves outdoors slightly later, say at 6am, will be greeted by a thin sliver or arc of the bright lunar disk above the western horizon, which will become progressively larger as the Moon continues to move out of the Earth’s shadow.
People sometimes ask why the Moon is visible at all during a total eclipse. The answer is that some sunlight, passing through the edge of the Earth’s atmosphere as seen from the Moon, is bent or refracted into the deepest part of the Earth’s shadow, so providing illumination even at the centre of the shadow.
Image of a solar eclipse taken from lunar orbit by the Kaguya spacecraft in 9 February 2009, a phenomenon visible from the Earth as a lunar eclipse. Note the ring of light surrounding the Earth’s black disk, caused by sunlight refracted through the atmosphere. CREDIT: Japanese Aerospace Exploration Agency.
Indeed, if one were to stand on the surface of the Moon and look back towards the Sun, the view would be reminiscent of a solar eclipse viewed from the Earth’s surface. The above image was taken by the Japanese Kaguya spacecraft orbiting the Moon during a lunar eclipse some 10 years ago. Sunlight refracted through Earth’s atmosphere is responsible for the “ring of light’’ effect, sometimes referred to as the “light of a thousand sunsets’’. The weather conditions in those parts of the Earth’s atmosphere, for example how dusty or cloudy it happens to be, determine how dark the Moon becomes during the period of totality.
In short, the colour and brightness of the Moon during a total lunar eclipse cannot easily be predicted. They depend on how centrally the Moon passes through the Earth’s shadow and on how cloudy or transparent are those parts of the Earth’s atmosphere that enable sunlight to reach the Moon. During a very dark eclipse the Moon may be almost invisible. Less dark eclipses may show the Moon as dark grey or brown; or as rust-coloured, brick-red or (if very bright) copper-red, or orange — again producing a range of photo-opportunities for the keen photographer.
View of the night sky as seen from Belfast generated by the freeware program XEphem in the vicinity of the eclipsed Moon at 0512 GMT on the morning of the 21st January. Note the M44 “Beehive’’ cluster to the upper left of the Moon and the bright stars Castor and Pollux to the right. CREDIT: XEphem/The Clear Sky Institute.
In any event, the lack of direct solar illumination will render the eclipsed Moon about as bright as the brightest stars in the sky and allows to make out faint, so-called “deep sky” objects that would otherwise be drowned out by moonlight. On this occasion (see diagram above), the Moon’s location at the border of the constellations Cancer and Gemini places it about 7 degrees below and to the right of the M44 open star cluster also known as the “Beehive”, creating another interesting photo opportunity. Further to the right lie Castor and Pollux, the brightest stars in Gemini.
Article by Michael Burton, Director of the Armagh Observatory and Planetarium
Our view of the cosmos is biased by the vista that is apparent to our eyes. This is what the view in what we call the optically visible portion of the spectrum. To the unaided eye it is a view of a universe full of stars, together with five planets, one Moon and of course the Sun. When augmented with a telescope, our eyes can then see a universe full of galaxies – giant cities of stars.
Yet this is not a representative view of the universe. It misses many types of astronomical objects. The electromagnetic spectrum stretches from low energy radio waves to extremely high energy gamma rays. Optical light takes up just a tiny portion of this spectrum, from blue light with a wavelength of 0.4 microns, to red light with a wavelength of 0.7 microns. A micron is a millionth of a metre, and to give that some perspective, the typical human hair is about 50 microns thick. So very small!
Schematic diagram showing the electromagnetic spectrum, from the radio bands to gamma rays. Credit: wikipedia.
Evolution has given us eyes responsive to optical light as this is the dominant portion of the electromagnetic spectrum emitted by our local star, the Sun. Our atmosphere, by good fortune, also happens to be transparent to optical radiation. So not only do the Sun’s rays reach us direct, so too does the light from the stars in the sky.
If our eyes had evolved to be sensitive to infrared light, for instance, radiation of slightly longer wavelength to optical light, they would have been sensitive to the heat emitted by objects. We would have been able to see in the “dark”. However, we would also have been largely unaware of the spectacle of the starry sky. For the Earth’s atmosphere also emits strongly in the infrared, so drowning out the weaker infrared light that comes from the stars. It is interesting to speculate how civilisation might have evolved in such conditions, without the vista of the night sky that ultimately stirred the development of the scientific methodology that underpins our modern, technologically-based society.
The Milky Way seen in optical wavelengths (top) and radio wavelengths (bottom). The optical image shows stars that are relatively nearby to the Sun and obscuration by clouds of dust. The radio image show atomic hydrogen gas from right across the Galaxy. Credit: NASA.
There is another region of the spectrum where radiation can reach us directly from distant objects in the cosmos. That is in the radio wavebands. Radiation with wavelengths from about 1cm to 10m can pass largely unobstructed through the atmosphere and so be detected by telescopes on the ground. Radio astronomy is concerned with the measurement of such radiation and then using it to better understand the nature of celestial objects.
Karl Janksy with the antenna he built to discover the first cosmic source of radio waves in 1933. Image credit: National Radio Astronomy Observatory (NRAO).
We are used to receiving radio signals broadcast by TV and radio stations. However it was a great surprise when, in 1933, Karl Jansky detected radio emission from space. Using a radio antenna that he built that is not unlike, in design, that now used for TV aerials, he was investigating the static interference in radio transmissions. In doing so he unexpectedly discovered a radio source of cosmic origin coming from the direction of the centre of our Galaxy.
While some radio telescopes of today still do look a bit like Jansky’s original antenna – arrays of dipoles sensitive to the longest wavelength radiation – most radio telescopes now look much closer to optical telescopes in form. Except that they are (generally) far, far bigger! Size is essential for a radio telescope if image clarity is desired. For the image resolution that any telescope can achieve is directly proportional to the wavelength of the radiation being measured, divided by the diameter of the telescope. Since radio waves are over a million times longer than optical waves, this means a radio telescope would have to be a million times larger to achieve the same image quality!
The 4m diameter Anglo Australian Telescope in Australia, a typical optical telescope used by professional astronomers. Credit: David Malin, Australian Astronomical Observatory.
The Lovell radio telescope at Jodrell Bank Observatory. At 76m in diameter it is the largest telescope in the British Isles. Credit Jodrell Bank Radio Observatory.
Actually it is more complicated than this because the atmosphere blurs the quality of optical images. Radio telescopes can also be combined together to achieve the resolution of a single telescope whose diameter is the size of their distance apart, a technique known as interferometry. Though the sensitivity is only the equivalent of the collecting area of the individual dishes, not the area they are spread over. Nevertheless, radio astronomers have been able to achieve remarkable fidelity in their best images, far better than that of the best optical images obtained of astronomical sources.
While optical astronomy is largely concerned with the study of stars, which emit much of their radiation in these bands, radio astronomy is mostly concerned with studying the gas of interstellar and intergalactic space. Very few stars emit significant amounts of radio emission. However, clouds of gas in space are prolific emitters of radio waves.
Centaurus A in the optical. A giant dust lane runs across the image, orthogonal to the radio jet. Credit: European Southern Observatory.
The galaxy Centaurus A seen in the radio. A vast jet of relativistic plasma is seen being expelled from near to the supermassive black hole in its core. Credit: National Radio Astronomy Observatory.
The centre of our Milky Way Galaxy seen in radio. Spiral-shaped filaments of gas are seen, which are illuminated by the intense radiation from the stars. Credit: National Radio Astronomy Observatory.
Clouds of atomic gas – largely hydrogen atoms in space – emit radiation with a wavelength of 21 cm. Molecules emit radiation of higher frequency (and shorter wavelength). For instance, the carbon monoxide molecule emits at a wavelength of 3 mm. Its measurement allows us to study the regions where stars form in our Galaxy, the cores of giant molecular clouds found mostly in the central plane of our Galaxy. [Note: carbon monoxide is the second most common molecule in space. However the vastly more abundant hydrogen molecule does not, in general, emit radiation, so it cannot be studied directly in space except in special circumstances]. Finally the hot, ionised gas around luminous stars emits radiation from isolated electrons in the gas, as they swing by the protons. This allows astronomers to study the intense activity and mass loss from these stars, a central part of the process that is recycling material from the stars into the gas that occurs as part of the galactic ecosystem.
The I-LOFAR radio telescope at Birr Castle with the Milky Way over head. I-LOFAR is led by an Irish consortium from Trinity of which Armagh is a member (Credit: I-LOFAR Intern Luis Alberto Canizares).
The centre of our Milky Way Galaxy seen in the infrared. The view is dominated by stars. Credit: Michael Burton, Anglo Australian Telescope.
The rapidly-approaching 2019 will let us mark a half-century since human beings took the first steps on a body other than the Earth, namely our own Moon. But, come the New Year, lunar exploration is likely to make the headlines for one other reason: a number of robotic spacecraft built by three different nations will attempt to repeat the feat accomplished by the Apollo programme and land on the Moon’s surface.
First off will be China’s Chang’e 4 spacecraft, expected to be launched at 18:15-18:34 GMT on Friday 7th December at the time of this writing. As the name suggests, it is the fourth in a series of probes China has sent to the moon over the last 10 years. The previous one, Chang’e 3, landed near a region called Sinus Iridum in 2013, the first lunar soft landing by a human artefact since 1976 [Remarkably, the Chang’e 3 lander is still sending back data after 5 years on the Moon].
Chang’e 4 will attempt another first: landing on the far side of the moon, in other words the part that is constantly out of view of observers on the Earth. For an observer on the far side, the sun comes and goes just as it does on the near side, but the Earth is always below the local horizon. The challenge of such a mission – probably the reason it wasn’t attempted before — is that the lander has no direct communications link with ground control on Earth, as the bulk of the Moon is in the way.
Mosaic of images taken by NASA’s Lunar Reconnaissance Orbiter spacecraft showing the moon’s far side. The South Pole-Aitken basin and Von Carman Crater are indicated by the circle and arrow respectively. Credit for original picture: NASA/GSFC/Arizona State University
Chinese engineers and scientists have got around that problem by launching a separate satellite to sit high above the lunar far side and relay data from the lander to Earth. This satellite, now named Queqiao or “Magpie Bridge” in Chinese, is already on-station and ready to act as the relay for the Chang’e lander. The intended landing site for the spacecraft is a 180-km wide crater called Von Carman at 45 deg south, roughly the latitude of New Zealand on Earth. Landing would probably take place on or around January 3, 2019. Like its predecessor, Chang’e 4 also carries a small rover that is intended to roam about the lunar landscape and study the surface far from the lander’s immediate vicinity.
The objectives of the mission are two-fold: First, the Moon itself. Von Carman crater forms part of an even larger depression thousands of km across, called the South-Pole Aitken basin or SPA for short. SPA is thought to be the largest and oldest crater on the Moon, formed when an asteroid or comet 100km or so across slammed on the then-newly-formed Moon 4.2 billion years ago, digging up material from deep within. By landing on SPA and sampling the soil, scientists hope to find out what the deep interior of the Moon is made of, test current models of how it formed and check that SPA is as old as they think it is.
The other scientific aim of the mission concerns the unique environment of the lunar far side.
Just as sunlight scattered by the Earth’s atmosphere prevents one from doing optical astronomy during the daytime, electronic devices on Earth – anything from microwave ovens to mobile phone networks – generate radio waves that prevent a really sensitive exploration of natural radio sources in the universe from the Earth’ surface and, in fact, anywhere in the solar system. But with the bulk of the moon effectively blocking all Earth-based transmissions, the lunar far side should be a much better place for astronomical radio observations. If Chang’e 4 confirms this, the day will not be far away where space-faring nations establish radio observatories on the lunar surface to explore the cosmos with unprededented sensitivity.
[Update on 08 Dec]: Chang’e 4 was successfully launched at 18:23:34 GMT yesterday upon a Long March 3B rocket from the Xichang Satellite Launch Centre in China and is now on its way to the Moon!
Detailed information on the mission, including a number of videos, may be found here:
Article written by: Tom Watts, PhD Student, Armagh Observatory and Planetarium
For this article we will be looking at five common theories and conspiracies, and giving our scientific insight into them. Below are the five topics we will cover.
The Apollo moon landings were faked
Planet X is going to kill us all
The Moon Landings Were Faked
On July 20th 1969, Neil Armstrong became the first of just 12 people to step foot on a celestial body that wasn’t Earth. This first step fulfilled the goal set by President John F. Kennedy just 8 years previously, and for many signalled the end of the Space Race with the Soviet Union.
Buzz Aldrin, the second man to walk on the moon, climbing down the LEM. Image Credit: NASA
In this iconic photo of Buzz Aldrin climbing down the ladder to the Moon’s surface, we see no stars in the sky, despite it being a deep, inky black. Some people think this lack of stars is evidence that the landings were faked here on Earth. In fact this is because the surface is bright, and the camera takes the photo so quickly that the faint light from the stars doesn’t have time to register on the film of the camera.
It is also sometimes claimed that passing through the Van Allen radiation belts, areas of high radiation due to particles from the Sun being trapped by the Earth’s magnetic field, would have been fatal to the astronauts. However the astronauts were protected by the metal skin of their capsule and flew through the belts so fast their radiation exposure was very low. The exposure the astronauts got was similar to that of a patient undergoing a CT scan.
A famous claim against the Moon landings is that the flags planted in the surface by astronauts flutter as if it were blowing in a breeze, something that wouldn’t happen in the vacuum of space. Because of the vacuum on the surface of the Moon NASA deliberately included a metal rod that the astronauts would erect within the flag to hold it upright. Because there is no air to cause friction on the flag and stop it moving, once the astronauts knocked it the flag would continue to move long after they had moved away, giving the appearance of it floating in the breeze.
There is an overwhelming amount of evidence that the Apollo program successfully landed 12 men on the Moon between July 1969 and December 1972, four of who are still alive today.
The Earth is flat
Despite it being known for over 2,500 years that the Earth is spherical, it is still believed by some that the Earth is flat.
We have evidence that the Earth is spherical in countless ways, from footage from high altitude aircraft and spacecraft, to our understanding of simple physics. Gravity always pulls an object towards the centre of mass of the body, and objects will try and get as close towards the centre, which means they will go to the lowest point they can find. The combination of these effects pulls an object of enough mass (to have a substantial gravitational field) into a sphere over enough time. This is called hydrostatic equilibrium.
Every other object we see in the sky of sufficient mass, such as large moons, planets and stars, is pulled into a sphere through these processes. It is only logical that Earth also follows this pattern for the same reasons, and everything we see in the world around us gives us no reason to think otherwise. We rely on our understanding of a spherical Earth for many things in our daily lives, with satellites in orbit giving us GPS, communication, and weather forecasting.
We know the Earth has gone through many periods of changing climate by studying ice cores. These allow us to examine how the atmosphere has changed with time, and how the temperatures have varied. From this and other methods, we know about past ice ages, and past spells of warmth.
Since the start of the industrial revolution, measurements have shown a significant change in the Earth’s climate. This can be attributed to the vast amounts of pollutants humans have been putting into the atmosphere, particularly greenhouses gasses such as carbon dioxide. Greenhouse gasses trap heat in the atmosphere that would otherwise be radiated away into space. This is because carbon dioxide is a good absorber of infrared light, which is how the Earth loses heat into space. This has meant global temperatures have been steadily rising for the past couple of centuries, and this is continuing today.
While global temperatures have been rising, it’s important to understand that global warming does not mean everywhere is going to be getting hotter all of the time. The rise in temperatures, along with the accompanying melting of the polar ice caps, cause significant changes to how weather patterns form and move. This results in global changes that alter rainfall, temperatures, and wind over a period of many years. This change appears to happen slowly by human standards, taking many decades, but on historical timescales the current phase of climate change is happening at a rapid rate. The current changes are happening too fast for some environments to adapts too, with nature struggling to keep up.
Armagh Observatory and Planetarium has been recording the weather every day since 1795. Our record has been included in recent climate research to show how our climate has changed over the years.
We can try and slow, or even halt this change entirely, by reducing the amount of pollutants we put into the environment. There is a global effort to reduce the amount of carbon dioxide being released into the atmosphere by switching to cleaner sources of energy, like solar and wind power, but there is still work to do. The planet has warmed by nearly 1ºC since the start of the 1900’s, which is 10 times the historical climate change rates, and we are still releasing about 35 billion tonnes of carbon dioxide into the atmosphere every year.
Planet X/Nibiru is going to kill us all
Over the past few decades it has often been claimed that a planet is on a collision course with Earth that will destroy our planet. It is normally claimed that the date of the collision will occur on various dates that involve ancient calendars (which are man made and have no bearing on the planets). Some of these supposed dates have already been and passed by without any incident.
We would already have detected any planet sized body large enough to destroy Earth from centuries, or even millennia, of looking up at the sky. The planets all the way out to Saturn have been known since antiquity. We would have seen any planet on an imminent collision course with Earth. It would be known about either by seeing it with our eyes and telescopes, or through its gravitational influence in the Solar System. Neither of these have been seen.
However, it has been theorised that a massive planet may be lurking on the outskirts of the solar system, as anomalies in the orbits of far out comets in the Kuiper Belt suggest that there could be a massive body out there somewhere influencing them. However, to date, searches for this distant planet have not shown any results, as such a body would be so far away it would be very hard to detect, let alone pose any danger at all to Earth.
Here you can see the hypothesised orbit of Planet 9 along with some other Kupier Belt Object (KBOs) including Sedna. At the centre of the image you can see the Sun and you can see just how far away it is. The other planets in our Solar System are not visible on this scale. Credit Caltech/R. Hurt (IPAC)
We’ve all heard stories of people waking up in the middle of the night and being abducted by aliens with tractor beams, taken away to be “probed”, before being returned to their beds with little or no evidence of their experience, other than a thrilling tale. Some have even told stories of being transported off to their abductees home star system, and others of aliens who walk among us, and are even in positions of global power.
In all likelihood, Earth has never been visited by life that originated elsewhere. While it is quite possible that alien life does exist somewhere in the universe, it is unlikely that intelligent aliens would have crossed the vast distances of interstellar space in the short, on astronomical timescales, amount of time that humans have inhabited Earth. It is unlikely that an alien civilisation even knows we exist yet, as we have only been sending out beacons of our existence into space that others could detect since the invention of radio. Since radio signals travel at the speed of light, our signals will have not yet reached many star systems, and even fewer that have the potential to host alien life.
That’s not to say aliens do not exist. Despite years of searching there is no evidence to either prove or disprove aliens existence as of yet, so we have no way to know if the universe is teeming with life, or if Earth is the only place that a series of incredibly unlikely chance events took place that have led to the planet filled with life that we see today.
In 1961 astrophysicist Frank Drake wrote down an equation that allows us to estimate how many alien civilisations there may be.
N = R∗ x fp x ne x fl x fi x fc x L
This equation tells us N, the number of alien civilisations we could communicate with. To calculate this we multiply how many new stars form in our galaxy each year (R∗), by the fraction of those stars that have planets (fp), by the number of those that are Earth-like and habitable (ne). These are all things astronomers can estimate reasonably well, however the next four terms in the equation are unknown. They are the fraction of planets that go on to develop life (fl), the fraction that then go on to form intelligent life (fi), the fraction of those that go on to develop a civilisation that has technology they could communicate with us with (fc), and finally the amount of time that civilisation will send out signals into space (L).
These final four terms could be almost any value, meaning that our Galaxy could be full of life that we haven’t yet detected, or that life could be such a rare occurrence that we are the only example of a technological civilisation to ever develop in the history of the universe. What values go in to the equation are up to you, so you can decide for yourself how likely it is whether or not we are alone in the universe.
Article written by: Apostolos Christou, resident Astronomer at Armagh Observatory and Planetarium
Some seven months ago, a NASA spacecraft called InSight was launched atop an Atlas 5 rocket and headed to Mars (Figure 1). If all goes well, the spacecraft will land on the Martian surface at around 8pm UK time this Monday 26th November and begin its science investigation. InSight is a fixed lander (see Figure 2 below), a much simpler affair than the Curiosity rover that arrived in 2012 and continues its trek across the floor of Gale crater to this day. Mobility, is however, not required for the specific aim of the mission.
Fig 1. An Atlas V launches through morning fog from Vandenberg Air Force base, California, on 5 May 2018 carrying the InSight spacecraft to Mars. Credit: Ben Smegelsky/NASA
As its name suggests, InSight will allow scientists to form a picture of the planet’s interior, by detecting seismic waves generated by marsquakes. It will help us better understand how other rocky planets, including Earth, were and are being created. As a bonus, it will also detect impacts by small asteroids, the so-called “meteoroids” on the surface to find out how often this happens on Mars and how the rate of impacts varies day-to-day and season-to-season. Though Mars, like the Earth, has an atmosphere that shields the surface from the very small meteoroids, its atmosphere is still too thin to provide effective protection against larger objects.
Modelling done by AOP Research astronomer Dr Apostolos Christou indicates that objects as small as a walnut could reach the surface still travelling at thousands of miles an hour, producing a small ‘pit’ upon impact. The Apollo lunar seismic experiment, a very similar experiment left on the surface of the Moon by the Apollo astronauts, made the surprising discovery that our natural satellite is occasionally hit by a barrage or “swarm” of boulder-sized meteoroids.
Fig 2. Depiction of the Insight lander on the surface of Mars. The dome-shaped object on the left is the seismometer. The device on the right is a heat flow probe. Credit: NASA/JPL-Caltech
As with the seismometer onboard InSight, the primary goal of the Apollo experiment was to study moonquakes. But a different kind of signal corresponded to the impacts of boulders coming from interplanetary space. The largest detected was the mass of a car. Some arrived as individual impactors, some were grouped in clusters. Work done by AOP’s Dr David Asher suggests that the most intense bombardment detected by the Apollo experiment was related to a swarm within the Taurid meteoroid stream thought to have formed by comet Encke over thousands of years. On Earth, meteoroids reach the ground less readily, tending instead to vapourise in the atmosphere. A Taurid swarm encounter manifests itself as an outburst of fireballs in October to November’s Taurid meteor shower. The near-absence of a lunar atmosphere allows meteoroids to hit the Moon’s surface directly and generate seismic signals. In this way, NASA’s latest foray to Mars will tell us if swarm encounters are also a feature of the Martian meteor year.