Presentation on theme: "“The universe is not only queerer than we suppose, but queerer than we can suppose” J.B.S. Haldane."— Presentation transcript:
“The universe is not only queerer than we suppose, but queerer than we can suppose” J.B.S. Haldane
Astronomy and Religion In 1600, the Italian philosopher, Giordano Bruno was burned at the stakes because he maintained the "heretical" notion that there were countless other worlds out there containing life. In the 18 th century, the pendulum shifted to the other extreme; many astronomers were convinced that every star had planets with life. Will Herschel (the man who discovered Uranus), even speculated that the sun was populated with life.
Church vs. Science The possibility of life on other planets is another topic which creates great debate between scientists and religious beliefs. Once again Old Testament biblical teachings tell us that one God created man in his image and all life on Earth. Would our Christian values be shaken by the presence of life on other worlds? What about intelligent, sentient life? How does the Catholic Church respond?
The Catholic Churches View The following are thoughts from Vatican Astronomer and U.S. Jesuit Brother Guy Consolmagno with the help of the British-based Catholic Truth Society in (The following quotes were taken from his interview with the Catholic News Service). "What Genesis says about creation is true. God did it; God willed it; and God loves it. When science fills in the details of how God did it, science helps get a flavor of how rich and beautiful and inventive God really is, more than even the writer of Genesis could ever have imagined”
The Churches View The limitless universe "might even include other planets with other beings created by that same loving God," Consolmagno added. "The idea of there being other races and other intelligences is not contrary to traditional Christian thought. "There is nothing in Holy Scripture that could confirm or contradict the possibility of intelligent life elsewhere in the universe," Consolmagno wrote.
The Churches View More recently, Father José Gabriel Funes, an Argentine Jesuit, told the Vatican newspaper: "Just there is a multiplicity of creatures on earth there could be other beings, intelligent ones, created by God.“ However the Jesuit astronomer went on to speculate that if intelligent beings exist in another solar system, "they might have remained in full friendship with the Creator," and thus might not require salvation as the human race does.
What conditions make Life on Earth Unique?
What Makes Earth Special? Planet Earth is the only known host for life, but we have now gained the technology to search other worlds within our own system and to locate planets in other systems. Is life unique on Earth or is life common throughout the ? What do you think? Let’s poll the class for opinions. What are the reasons given for their opinions? Let us start by defining the special circumstances that allow for life on Earth.
Video Introduction Let’s watch these videos to get an idea of the astronomical and Biological requirements for life: Video: A Teacher’s Guide to: What makes Life on Earth Possible? IMAX: The Secret of Life on Earth
1. Temperature (The Habitable Zone) and the presence of Water! A stars habitable zone is defined as the region in which orbiting planets could be habitable (contain life. The most important factor is temperature. Since life as we know it requires water on its surface, temperatures must be between 0 and 100°C somewhere on the surface. All the chemical reactions of life occur in aqueous conditions – in other words with chemicals dissolved in water! High temperatures cause proteins/DNA to degrade. These are the molecules of life. Very low temperatures mean that chemical reactions (including biological reactions) occur slowly.
The Habitable Zone
Habitable zones vary for each star system. At right, the conservative and optimistic habitable zones for our Solar System.
2.The Effect of Gravity A planet (or moon) must have enough mass to have substantial enough gravity to maintain an atmosphere. Mercury and the moon, despite being massive enough to be spherical, are not massive enough to keep an atmosphere. Similarly, too much gravity may crush possible life.
3.An atmosphere Volcanic activity furnished Earth with an early atmosphere. Though this atmosphere did not contain oxygen gas, it supplied the chemicals of life – carbon (in the form of CO2), nitrogen (in the form of ammonia NH3), oxygen and nitrogen in the previous compounds and a wide variety of important metals and non-metals in abundance. An atmosphere is often required to trap heat and to maintain stable surface temperatures. Atmosphere’s also provide protection against smaller meteorites.
Atmospheres and Surface Temperatures
3.Atmosphere (Protection from Meteor Bombardment) Many astrobiologists have suggested that life took hold on the surface of Earth several times only to be exterminated by a massive meteor bombardment in each case. Once Earth orbited in a clearer path, life was able to take hold permanently.
4.A Magnetic Field A magnetic field is required to protect an atmosphere from being blown away by the forces of the solar wind. The solar wind is a flow of radiation and charged particles emanating from a star. These particles can interact with the particles in a planetary atmosphere and slowly remove it. A magnetic field can be created by a molten, spinning iron core (like Earth) or by a rotating charged metallic layer like that seen in the Gas Giant planets. We know that a planet’s age and size can be a factor. Mars was large enough to maintain an atmosphere, but its liquid core “froze” and its magnetic field was lost!
5.A Stable Climate (Axial Tilt) Wildly fluctuating temperatures and sudden changes of climate do not allow living things to adapt. It is thought that the Earth’s very small wobble on its rotational axis keeps these climatic changes to a minimum. Remember that this wobble is significantly lessened by the presence of our large moon and its gravitational influence. Similarly, an orbit with low eccentricity will result in a much more stable climate.
6.A Stable Medium Sized Star Our sun has released radiation with little variation in its quantity for billions of years. This stability is critical for Life on Earth. A star whose energy output was variable would have a wildly changing habitable zone and life could not take hold. Large bright stars burn out very quickly and would not leave much time for life to take hold. Small dim stars have been suggested as possible hosts for planets with life but these planets would have to obit vey close to their stars.
7.Location in the Galaxy The Sun location in the “galactic suburbs” of the Milky Way Galaxy is fortuitous. The cores of most galaxies contain a much higher density of stars and such high energy objects as black holes and quasars. The intense radiation of these regions would likely strip away the atmosphere of any planets and bake their surfaces. Our search for exoplanets occurs in the “Galactic Habitable Zone”
8.Availability of heavy elements. Earth has an abundance of heavy elements – many of which are found within complex living organisms. Earth must have been formed in a region of space where its protoplanetary disk formed from a nebula that contained heavy metals. This is only possible if the nebula was produced near a supernova (the only source of elements heavier than iron)
9.Plate Tectonics A geologically active planet will have moving tectonic plates (crust). This process creates volcanic activity which releases gases such as CO2 and recycles elements that get trapped in the crust. Early life is likely to have formed around hydrothermal vents. Life used the heat energy and abundance of chemicals to sustain life functions.
10.Time for Evolution The process of evolution is very slow. It took nearly 4 billion years for life to develop past the single-cell stage! It has been 600 million years since the first explosion of multi-cellular life. Short lived stars and planets that lose their atmosphere too quickly are not suitable for the development of complex life.
The Drake Equation The Drake Equation was developed by Frank Drake in 1961 as a way to focus on the factors which determine how many intelligent, communicating civilizations there are in our galaxy.
The Drake Equation The Drake Equation is: N = R * f p n e f 1 f i f c L It depends on seven factors R * = The number of suitable stars form each year in our galaxy. f p = the fraction of these stars that have planets n e = the number of these planets suitable for life f 1 = the fraction of these planets that develops intelligent life f i = is the fraction of these life forms that develop intelligence. f c = is the fraction of these intelligent life forms that choose to communicate with other civilizations. L = the lifetime of such as civilization. One of the problems of this equation is that it cannot be calculated with any certainty since no accurate value can be determined for any of the 7 variables. However, it gives us a good framework to estimate the probability of alien life.
The Drake Equation Drake’s calculation for our Galaxy based on data from his time period: N = R * f p n e f 1 f i f c L = 5 x 50% x 2 x 100% x 20% x 100% x = possible civilizations in our galaxy.
The Drake Equation o SETI (Search for Extra-Terrestrial Intelligence) gives the following data: R * = The number of suitable stars form each year in our galaxy = 100 billion f p = the fraction of these stars that have planets = 20 to 50% n e = the number of these planets suitable for life = 1 to 5 f 1 = the fraction of these planets that develops intelligent life = 0 to 100% f i = is the fraction of these life forms that develop intelligence = 0 to 100% f c = is the fraction of these intelligent life forms that choose to communicate with other civilizations = 10 to 20% L = the lifetime of such as civilization = 100 to N = ? o Go to the SETI website to calculate your own value! on.html on.html
What about Extraterrestrial Life? Evidence that life could exist on other worlds: 1. Amino Acids the building blocks of life These have be formed in a lab in simulated primitive atmospheres. The Miller-Urey Experiment (The Primordial Soup). Watch The conditions of this experiment have since been determined to be dissimilar to the actual conditions of the early Earth. The term abiogenesis is used to describe the development of living organisms (or life processes) from inorganic compounds and abiotic conditions. Amino acids have been found in meteorites. This suggests that life might have been carried to Earth from “outer space”, a theory called Panspermia.
What about Extraterrestrial Life? 2. Extremophiles Micro-organisms adapted to environments once thought so extreme that life could never exist there in any form. Examples Light and Oxygen-free environments like the bottom of the ocean No sun-light environments like caves Acidic environments like around “Old Faithful” in Yellowstone National Park. Many biologists believe that the first living organisms on our planet lived in these extreme conditions (on an Early Earth that was very hostile to life)
Extremophiles - Hydrothermal Vents (2:52 Nat Geog) (4:00 Evolution of Life on Earth) (4:42 - no audio, music only, great video footage) (8:45 - extremophiles) =1&list=PL1HikUR5c27lxTOv9mU3HzLe8dfM3wAln (4:56 - extremophiles) =1&list=PL1HikUR5c27lxTOv9mU3HzLe8dfM3wAln
Possibility of Life in Our Solar System Given that life can form in extreme environments - it is thought life could exist in extreme environments elsewhere in our solar system. Extremophiles also hint at the development of life on Earth. Here are the top five solar objects in our solar system that might be able to support life:
5. Io Jupiter’s moon Io is one of the few solar system moons to support an atmosphere, and it contains complex chemicals promising for life. Volcanism on the moon also makes it warmer than many other. Io is still a long shot, though, because its location inside Jupiter’s magnetic field means it is constantly being pelted with lethal radiation. Its violent surface also seems inhospitable, with temperatures often too cold to support life, as well as molten hot spots that are equally deadly.
4. Titan Saturn’s largest moon looks suspiciously like it might have hosted life, because its thick atmosphere is rich in compounds that often mark the presence of living organisms. For instance, Titan’s air is filled with methane, which is usually destroyed by sunlight. On Earth, life constantly replenishes methane, so it might similarly be responsible for the methane on Titan. Titan is rather cold, however, and if liquid water exists, it must be deep beneath the frozen surface.
3. Mars The red planet is the most Earth-like of solar system planets, with a comparatively similar size and temperature range as our own planet. Large bodies of water ice lie on Mars’ poles, and there’s a reasonable chance of liquid water beneath the surface. The thin atmosphere on the planet is not strong enough to shield the planet against lethal solar radiation, though microbes could potentially exist beneath the surface.
2. Europa Jupiter’s moon Europa also seems a possible stomping ground for E.T. due to its potential water and volcanic activity. Though the surface seems to be frozen, many suspect that buried underneath is an ocean of liquid water. Microbial life could potentially survive near hydrothermal vents on Europa, as it does on Earth.
1. Enceladus The sixth-largest moon of Saturn has been called the most promising possibility for life thanks to its welcoming temperature and the likely presence of water and simple organic molecules. The surface of the icy moon is thought to be about 99 percent water ice, with a good chance of liquid water beneath. The moon seems to have a boiling core of molten rock that could heat the world to the toasty temperatures needed to give rise to life.
The Search for Other Planets AND the Search for Extraterrestrial life
Locating Exoplanets Video: (Exoplanets: Are there other Earths) (National Geographic: Alien Planets) Difficulties with locating Exoplanets 1. Planets don’t produce any light of their own. 2. They are an enormous distance from us. 3. They are lost in the blinding glare from their parent star.
Techniques for Locating Exoplanets 1. Doppler Wobble A star orbited by a planet will wobble due to the gravitational pull of the planet. This wobble shifts the stars absorption spectrum between the red and blue ends. The amount of shift allows astronomers approximate the planets size and mass. The doppler shift is very small (1/10,000,000 th of a wavelength), thus detection equipment must be very sensitive. As a result this technique has only been available for a decade.
The Doppler Wobble in Action
Locating Exoplanets 2. Transits A planet passing in front of a star minutely dims the light of a star. This allows astronomers to measure the orbital period, diameter and atmosphere of the exoplanet. The dips in the stars brightness are miniscule - usually less than 1%
Locating Exoplanets 2. Transits The Kepler Space Telescope (shown below) is designed to look for transiting planets in front of stars. The data from 5 exoplanets is shown below.
The Kepler Mission NASA has an entire website dedicated to the Kepler Spacecraft and its mission to find exoplanets (http://www.nasa.gov/mission_pages/kep ler/overview/index.html#.VEcfOWejI6A )http://www.nasa.gov/mission_pages/kep ler/overview/index.html#.VEcfOWejI6A The Kepler Spacecraft collects light using a special telescope called a photometer and has a very wide field of view (105°) The spacecraft stares at the same small portion of space continually for 3.5 years and collects light continuously at over 100,000 stars. It uses the transit method of detecting exoplanets and needs this amount of time to see the minute changes in light intensity. The Kepler Mission will soon come to an end and will be taken over by the ESA’s Plato mission
Locating Exoplanets 3. Astrometry Astrometery is a long used technique to precisely measure the position of a star in the sky. Today, planet hunters use astrometry, they look for a minute but regular wobble in a star's position. If such a periodic shift is detected, it is almost certain that the star is being orbited by a companion planet. This technique was used in early planet hunting, but not recently. The future SIM mission will hunt for exoplanets using this method. Similar to the Doppler Wobble Method, the star’s positional wobble is measured except using a star’s position vs. spectrometry.
Locating Exoplanets 4. Direct Imaging Blocking a star’s light has yielded images of 11 planets
Locating Exoplanets 5. Gravitational Microlensing If a star and planet pass in front of another star, their gravitational fields act as a lens, bending the light from the far star in a distinctive way. The lensing causes the intensity of the star’s light to increase (like any lens) If a planet happens to be orbiting the star, a slight additional lensing effect is added and the star shines brighter.
Kepler Mission Discoveries
Discoveries As of October 2010, astronomers have found evidence of the existence of 490 exoplanets. By 2014, over 2000 exoplanets have been found. Most of these planets are much bigger than our planet because planets our size are often too small to see at these great distances. The easiest planets to spot often orbit stars at very close range, with orbital periods measured in days not years. Transits must be fast to be noticed. Recent work has found an increase in Earth sized planets
Discoveries Most planets are thought to be similar to Jupiter (large gas giants) but recent work has detected Earths and Super-Earths (rocky planets with masses 10 times our planet’s mass. The search for life is focused on Earth-like planets found in stellar habitable zones - more of these planets are coming to light.
Top 10 Exoplanets: Weird Worlds in a Galaxy Not So Far Away A look at some of our extreme planetary neighbors right here in the Milky Way Galaxy from an article produced by Adam Hadhazy for Scientific American in 2008
10. FIRST EXOWORLD: The first solid evidence for an exoplanet (extrasolar planet) came in 1992 when scientists calculated that two bodies must be orbiting the pulsar PSR 1257 Distance from Earth: 978 light-years (One light-year equals the distance light in a vacuum travels in a year: 5.88 trillion miles, or 9.46 trillion kilometers.) Exoplanet Mass: 4.1, 3.8 Earths (0.013 and Jupiter)
TYPICAL STAR; EXTRAORDINARY PLANET The first exoplanet spotted around a Main Sequence star similar to our sun, gaseous 51 Pegasi b completes an orbit around its host star every four days. Many exoplanets found after this one are very similar "hot Jupiters," named for their size and proximity to their star. Distance from Earth: 48 light- years Exoplanet Mass: 0.47 Jupiter
8. SURVIVOR OF APOCALYPSE: V392.1 Pegasi b. distinguishes itself as the only planet known to orbit a star that has passed through its red giant phase. Remember when our own sun goes red giant in about it will likely swallow Mercury and Venus and, if it doesn't also envelop Earth, will scorch the planet: boiling off Earth's oceans, eventually leaving the once-verdant world a barren cinder. Distance from Earth: 4,550 light- years Exoplanet Mass: 3.2 Jupiters
7. POTPOURRI OF PLANETS: Distance from Earth: 44 light-years Exoplanet Masses: Range from 18 Earths to four Jupiters Astronomers discovered a fifth planet around the sunlike star 55 Cancri in 2007, making it the most planet- populated one outside our own--so far. All five confirmed planets in the system are jumbo versions of Earth and its neighbors, including a rocky mega-Earth and a gas giant four times as massive as Jupiter.
6. FREAKISHLY FROZEN WORLD: Scientists think Gliese 436 b (aka GJ 436 b), a Neptune-size exoplanet, is too heavy to be all gas but not heavy enough to be entirely rock. They surmise that in addition to gas and rock, it also contains a kind of pressurized, high-temperature ice that only exists on Earth in laboratories. Distance from Earth: 33 light-years Exoplanet Mass: 22 Earths (0.07 Jupiter)
5. NOT TOO HOT OR NOT TOO COLD. When astronomers spotted Gliese 581.C, it set off a flurry of reports that this exoplanet fell within the so- called Goldilocks Zone. Gliese 581 c orbits closer to its star than torrid Mercury orbits the sun, but the host is a dwarf star 50 times cooler than our sun, which researchers thought placed it in that star's habitable zone. Distance from Earth: 20.5 light- years Exoplanet Mass: five Earths (0.016 Jupiters)
4. EXOHOTTIE: HD b ranks as one of the hottest known exoplanets, with a lead-boiling surface temperature of around 3,700 degrees Fahrenheit (2,000 degrees Celsius). Tricky measurements of light reflecting from its surface suggest that this world may be pitch-black in color, perhaps because of a strangely high concentration of heavy, metallic elements in its atmosphere. But even in that case, it may glow red like an ember from all that heat. Besides its fearsome exterior, researchers believe this gaseous "hot Saturn" has the largest known planetary core, estimated at about 70 to 90 Earth masses.
3. IT'S A SMALL(ER) WORLD: Besides being the first exoplanet ever directly observed from Earth as it transited in front of its host star, it is also shrinking. Its proximity to the inferno of its host star superheats the planet to an estimated 18,000 degrees Fahrenheit (10,000 degrees Celsius), which researchers believe is causing it to sweat off about 10,000 tons (9,000 metric tons) of atmospheric hydrogen every second, forming a cometlike tail. It is thought that HD b might eventually lose its entire atmosphere. The world was also the first exoplanet to give up evidence of water vapor in its atmosphere, followed by the discovery of methane.
2. EARTH TIMES THREE: Distance from Earth: 1,000 light years Exoplanet Mass: 3.3 Earths The exoplanet MOA-192 b, which orbits a purplish star in this artist's impression, is the smallest discovered so far, measuring about 3.3 Earths in mass. It revolves about a dim star that is about one twentieth the mass of our sun, making this the planet with the teensiest host star, to boot. This star's diminutive size, however, is quite common in the universe, so finding that it can sport planetary bodies encourages researchers about the odds of finding Earthlike planets.
1. PRIMORDIAL PLANET: Distance from Earth: 5,600 light-years Exoplanet Mass: 2.5 Jupiters Exoplanet PSRB b is believed to have formed an incredible 13 billion years ago, less than a billion years after the big bang. Aptly nicknamed Methuselah, this probable gas giant resides in an ancient type of galaxy known as a globular cluster, where it orbits two stellar hosts, a dwarf star and a pulsar, both remnants of larger stars. It is thought that Methuselah once orbited a common yellow star like our sun, which became a red giant, giving up its matter to a dense neutron star--the latter of which became a spinning pulsar in the process. Packed in amongst other stars in the cluster, scientists think it is likely that Methuselah has been blasted by radiation from many supernovae over its lifetime. It however, indicates that a long time ago, in a globular cluster far, far away, a world can exist.