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STEM for TY Teachers
Discovering Our Place in the Universe
Day 2

Mark Bailey and Libby McKearney, Armagh Observatory


H&S, Housekeeping etc.
! This is a non-smoking building ! Morning tea and lunch will be served: ! Fire alarm, fire escapes ­ I will lead you to our fire assembly point, please
remain there until I check your name off the register and only return here when advised to do so.

! Please be aware of any trip hazards (trailing leads, steps etc.) ! Location of facilities

! Evaluation ­ please continue to fill out your evaluation form as we go through
today and tomorrow!

! Second form on your table.


Our Programme for Today


Reminder: Main Learning Objective
To provide TY Teachers/Coordinators with sufficient knowledge of astronomy and related sciences to give them the confidence and skills to introduce some aspects of astronomy to their TY students.


"Earth's Place in Space: Bringing Heaven Down to Earth" Talk by Mark Bailey


Gap tasks!


Moon: Relative Size and Phases
Moon's diameter (3476 km) is 27%, i.e. roughly one quar ter, that of the Ear th Lunar phases depend on relative positions of Ear th, Moon and Sun as both Ear th and Moon revolve around the Sun ...
From RAS Leaflet

Images from NASA


Moon: Orbit Always Concave With Respect to Sun
New Moon

Heliocentric View
Last Quar ter Full Moon

First Quar ter

Geocentric View


Orbit Around Common Centre of Mass: Produces Two Tidal Bulges

From RAS Leaflet

From McCully "Beyond The Moon"


"Spring" and Neap Tides: Depend on Alignment of Moon With Sun


Our Programme for Today
Outline Programme for Saturday in Armagh:

Please make your way to Armagh Planetarium

9:30 10:45 11:15 12:15 12:30 13:15 14:00 14:30

Planetarium Show, tour and discussion on bringing a school group Short walk back to Observatory for tea/coffee at 11am Sun, Stars and Galaxies Q&A Human Orrery
(umbrellas possibly!)

Lunch in Observatory and observing the Sun/Moon outside if clear Plenary, evaluation, return to soap-box. End of course, free time in Armagh and return to Donegal.

As we hope to observe outdoors on Friday night in Armagh, please bring warm clothes (warm coat, hat, scarf, gloves etc.) and binoculars if you have them. Just in case, for the outdoor tours, please bring waterproof clothing, an umbrella and comfortable, waterproof footwear!

Earthballs are funded by the RAS as part of its contribution to UNAWE education and public understanding of astronomy.


Core Theme 4 Sun, Stars and Galaxies
Sun as a star; formation and origin of stars, composition etc.; exo-planetary systems; other stars (single, binary etc.); star clusters; galaxies; galaxy clusters etc.; and the Universe (cosmolog y and new ideas).


Sun, Stars and Galaxies
The Nature of the Sun and Other Stars; Stellar Evolution; the Content and Structure of Galaxies and the Universe as a Whole...


Sun


Solar Wind and Magnetosphere


Aurora: Nor thern/Southern Lights


Different Types of Stars
! Main-Sequence Stars - Young Stars: These stars produce
energ y through nuclear fusion as they conver t Hydrogen to Helium. Most stars (about 90%) are Main-Sequence Stars. For these stars, the hotter they are, the brighter they are. The Sun is a typical Main-Sequence star. stars like our Sun, or tiny (Ear th-size) "white dwarfs", the compact remnants of stars like our Sun. Some mainsequence stars can be up to 20 times more massive than our Sun and much brighter. like the Sun.

! Dwarf Stars: The name "dwarf " can be used to describe

! Yellow Dwarf Stars: Yellow dwarfs are main-sequence stars


Her tzsprung-Russell Diagram


! Red Dwarf: The term "red dwarf " usually refers to a

small, cool, very faint, main-sequence star whose surface temperature is under about 4,000 K. Red dwarfs are the most common type of star. Proxima Centauri is a red dwarf.

! Giant and Supergiant Stars ­ Evolved, Large Stars ! Red Giant: A red giant is a relatively old star whose
diameter is about 100 times bigger than it was originally, and has become cooler (the surface temperature is under 6,500 K). They are frequently orange in colour. Betelgeuse is a red giant. It is about 20 times as massive as the Sun, but about 14,000 times brighter than the Sun, and about 600 light-years from Ear th.

! !


Betelgeuse


! Blue Giant: A blue giant is a huge, very hot, blue star. It
is a post-main sequence star that burns helium.

! Supergiant: A supergiant star is the largest known type
of star; some are almost as large as our entire solar system. Betelgeuse and Rigel are supergiants. These stars are rare. When supergiants die they explode as a supernova and may produce black holes.


Eta Carinae and Humunculus Nebula


Faint, Virtually Dead Stars:

! White Dwarf: A white dwarf is a small, very dense, hot
star that is often made mostly of carbon. These faint stars are what remain after a red giant star loses its outer layers. Their nuclear cores are depleted.

! They are about the size of the Ear th (but around

200,000 times more massive). They will eventually lose their heat and become a cold, dark black dwarf. Our Sun will someday turn into a white dwarf and then ultimately a black dwarf. The companion of Sirius is a white dwarf.


Comparison Between White Dwarf and Ear th: Extreme Matter


! Brown Dwarf: A brown dwarf is a "star" whose mass is too

small to have nuclear fusion occur at its core (the temperature and pressure at its core are insufficient for fusion). A brown dwarf is not very luminous. It is usually regarded as having a mass between approximately 1/100 and 1/10 that of the Sun. star which is composed mostly of tightly-packed neutrons. It has a thin atmosphere of hydrogen. It has a diameter of approximately 10 km and a density of roughly ten million billion times that of water. powerful magnetic field that emits energ y in a very narrow beam as it rotates, leading ­ like a lighthouse ­ to intense pulses of observed radiation.

! Neutron Star: A neutron star is a very small, super-dense

! Pulsar: A pulsar is a rapidly spinning neutron star with a very


! Binary Stars: Many stars are found in pairs (binaries) or
multiple systems.

! Double Star: A double star is two stars that appear

close to one another in the sky. Some are true binaries (two stars that revolve around their common centre of mass); others just appear double because they happen to lie along the same line-of-sight from Ear th. revolve around their common centre of mass (the barycentre). About half of all stars are in a group of at least two stars. Polaris (the pole star of the Nor thern Hemisphere of Ear th) is par t of a binary star system.

! Binary Star: A binary star is a system of two stars that


Neutron Stars and Pulsars: Even More Extreme Matter

Roughly same mass as the Sun (2 x 1030 kg); roughly same size as Halley's comet!


! Eclipsing Binary: An eclipsing binary is two stars that

appear to be a single star varying in brightness. The variation in brightness is due to the stars periodically obscuring or enhancing one another. Such binary star systems happen to be tilted (with respect to us) so that their orbital plane is viewed from the edge rather than face-on. of binary star in which one of the stars is a compact, evolved object such as a white dwarf, neutron star, or black hole. As matter is stripped from the normal star, it falls at very high speed onto the collapsed star, producing X-rays.

! X-ray Binary Star: X-ray binary stars are a special type


! Variable Stars - Stars that Vary in Luminosity: Many stars,
even the Sun, can vary in lumino light output by a very significant and can therefore be recognized These can be used as "standard distances. sity. Some change their amount in a regular way at very great distances. candles" to estimate

! Cepheid Variable Stars: Cepheid variables are very

luminous stars that regularly pulsate in size and change in brightness. As the star rapidly increases in size, its brightness increases; then, it slowly decreases in size again, and its brightness falls. seen millions of light years away and used to calibrate the distance scale of the Universe. Polaris and Delta Cephei are examples of Cepheids.
End of star types.

! Because of their intrinsic luminosity Cepheid stars can be


Nova and Supernova
! A supernova is a stellar explosion that is more energetic
than a nova. Plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. energ y as the Sun is expected to emit over its entire life span. The explosion expels much or all of a star's material at a velocity of up to 30,000!km/s (10% of the speed of light), driving a shock wave into the surrounding interstellar medium. This shock wave produces an expanding shell of gas and dust called a supernova remnant.

! During this shor t interval a supernova can radiate as much


! Nova (plural novae) means "new" in Latin, referring to
what appears to be a new star shining in the celestial sphere. Way since 1604, the number of supernova remnants indicates that on average such an event occurs about once every 50!years in the Milky Way.

! Although no supernova has been observed in the Milky

! Supernovae play a significant role in enriching the

interstellar medium with the heaviest elements. Fur thermore, the expanding shock waves from supernova explosions can trigger the formation of new stars.


EXO Planets
! Exoplanets: an extrasolar planet or exoplanet, is a
planet outside the Solar System. By early 2012, more than 700 extrasolar planets (in 571 planetary systems and 81 multiple-planet systems) have already been identified. data from the HARPS mission indicates that this includes more than half of all Sun-like stars. Data from the Kepler mission has been used to estimate that there are at least 50 billion planets in our own Galaxy. The first confirmed detection was in 1992.

! A substantial fraction of stars have planetary systems -


Transit of Venus and demo of blink method in school


Other life?!!
! Children will ask! ! ET? ! Recent US citizens' petition to reveal if their government
really knew anything about aliens on Ear th ­ "No"!

! The discovery of extra-solar planets has intensified

interest in the possibility of extraterrestrial life. Scientists look for the signature of water or chemicals which may sustain or indicate life. Posters on various web-sites (e.g. Observatory).


Microbes


Nebulae

"Pillars of Creation" in the Eagle Nebula


Orion Nebula and Proplyds

Orion Nebula imaged from Armagh (Simon Jeffery)

Space Telescope image of protoplanetary discs in Orion Nebula


! Nebula ­ often very beautiful images! A nebula (from Latin:

"cloud" pl. nebulae), is an interstellar cloud containing largely hydrogen, helium and other gases, as well as interstellar dust. Originally, nebula was a general name for any extended astronomical object, including galaxies beyond the Milky Way (some examples of the older usage survive; for example, the Andromeda Galaxy is still described as the Andromeda Nebula. Nebula. This nebula is depicted in one of NASA's most famous images, the "Pillars of Creation". In these regions the formations of gas, dust, and other materials "clump" together to form larger masses, which attract fur ther matter, and eventually become massive enough to form stars. The remaining materials are then believed to form planets, and other planetary system objects.

! Nebulae often form star-forming regions, such as in the Eagle


Galaxies of Different Types


Galaxy Types: Galaxies come in various sizes and shapes. They can have as few as 10 million stars or as many as 10 trillion. (The Milky Way has about 200 billion stars). In 1936, Edwin Hubble classified galaxy shapes in the Hubble Sequence.


! Elliptical: These have a faint, rounded shape, but

they're largely devoid of star-forming gas and dust, with no visible bright stars or spiral patterns. Elliptical galaxies probably comprise about 60 percent of the galaxies in the Universe. They show a wide variation in size - most are small (about 1 percent the diameter of the Milky Way), but some are many times larger. galaxies. They're bright and distinctly disk-shaped, with star-forming gas, dust and bright stars in the spiral arms. Because spiral galaxies are bright, they make up most of the visible galaxies, but they're thought to make up only about 20 percent of the galaxies in the Universe.

! Spiral: The Milky Way is one of the larger spiral


Some Galaxy Images


! Irregular: These are small, faint galaxies with large

clouds of gas and dust, but often no spiral arms or bright centres. Irregular galaxies contain a mixture of old and new stars and many tend to be small, about 1 percent to 25 percent of the Milky Way's diameter.

! Some more galaxy images:

Spiral galaxy M31 in Andromeda

Giant elliptical galaxy Centaurus A


Gravity
! Every time you jump, you experience gravity. It pulls you
back down to the ground. Without gravity, you'd float off into the atmosphere along with all of the other matter on Ear th. on a scale or toss a ball up into the air. It's such a constant presence in our lives, we seldom marvel at the mystery of it but even with several well-received theories out there attempting to explain why a book falls to the ground (and at the same rate as a pebble or a couch, at that), they're still just theories. The ultimate cause of gravity remains a mystery.

! You see gravity at work any time you drop a book, step


! So what do we know about gravity? We know that it

causes any two objects in the Universe to be drawn to one another. We know that gravity assisted in forming galaxies and other structures in the known Universe, that it keeps the Moon in orbit around the Ear th and so on. Newton defined gravity as an attractive force, one that attracts all objects to all other objects. However, Alber t Einstein said that gravity is the result of the curvature of space-time. These two theories are the most common and widely held (if incomplete) explanations of gravity.

! As for the science behind the action, we know that Isaac


The Expanding Universe!!
! The Expanding Universe, the theory developed from the
observed correlation between the red shifts of celestial bodies and their distances, suggests that the space between galaxies is expanding. This causes distant galaxies to appear to be moving away from us with a speed that increases with distance, just like the separation of dots on a balloon as you blow it up. structure, and space-time relationships of the Universe. Cosmologists study the Universe as a whole: its bir th, growth, shape, size and eventual fate. Modern cosmolog y is dominated by the Big Bang theory, which brings together observational astronomy and par ticle physics.

! Cosmology is the discipline that deals with the origin,


The Expanding Universe


! The Big Bang theory is the prevailing cosmological

model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in its present continuously expanding state. According to recent measurements, observations and scientific evidence, this original state existed around 13.7 billion years ago, which is currently considered as the age of the known Universe. Prior to the hot stage of the Big Bang, a very shor t-lived earlier stage of Inflation is thought to have occurred.
End of presentation.