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WhatIs…?
What is a Meteor?
What is a Comet?
What is a Star?
What is a Nebula?
What is an Open Cluster?
What is a Black Hole?
What is a Quasar?
?
??
?
WhatIs
Astronomy?Reflection nebula IC4606 by George Greaney
What is Astronomy?
Astronomy is a science that attemptsto understand the make-up and the history of the universe.
Galaxy M83 in Hydraby George Greaney
Basically, if its off this planet its a study of some realm of astronomy.
As one might imagine that covers an awful lot of subjects, even more than we know right now. A short list of subjects include:
•NGC 253, galaxy in Sculptorby George Greaney
•Stars •Nebula •Planets •The Sun
•The Great Andromeda Galaxy by George Greaney
•Star clusters •Galaxies •Galaxy clusters •Dark matter •Black holes
Galileo Observatory in Italy
An Astronomer is a Scientist, skilled in Mathematics, Physics, and Astronomy
Most Professional Astronomers work for Universities or Government Agencies
Source: The Berkeley Cosmology Group
Galileo Galilei (1564-1642)
Whatis an Astronomer?A night watchman with a college education?
Astronomer Serena Kim at work At Cerro Tololo in Chili
Few astronomers spend much time looking through a telescope. Most operate telescopes from a control room or even from their computer at home via theInternet.
Typical astronomers only spend one or two weeks eachyear observing, and the rest of their research time analyzing their data.
Source: Applied Theoretical and Computational Physics DivisionLos Alamos National Laboratory
Amateurs and their tools
What is an AmateurAstronomer?
What is an AmateurAstronomer?
Although the Term has different meanings for different people, a basic definition would include anyone who looks into the sky, and wants to see or learn more.
Tonight
Youare an Amateur Astronomer
WhatIs a
Meteor?
A Meteor is a bright streak across the sky,or a “Shooting star” produced when a small piece of comet or asteroid, called a meteoroid, enters the Earth’satmosphere.
Source:The Lowell Observatory
A Meteor from the annual Leonid Meteor shower lights the sky
A meteoroid is the dust, rock, or debris still in space. It could be a chunk of an asteroid or comet.
The Giant Asteroid Gaspra
What is a Meteoroid
?
Source:NASA
A meteorite is a meteor that actually falls to the ground. Most meteors burn up and never make
it to the ground.
The Giant Asteroid Gaspra
Whatis a
Meteorite?Meteorite Damage, Peekskill, NY
Source:NASA
WhatIs a
Comet?Image by Dave Dockery
Astronomical Society of Las Cruces
Comet Ikeya Zhang
A comet is basically a ball of ice and dust in space. The typical comet is less than 10 kilometers across. Most of their time is spent frozen solid in the outer reaches
of our solar system.
Image by Harvard-Smithsonian Center for Astrophysics
Comet Hale Bopp
A comet orbits around the sun, in a wide, elliptical path. When a comet gets within a few million miles of the sun, it begins to melt, leaving a tail of gas and dust that is blown by solar winds
Image by Harvard-Smithsonian Center for Astrophysics
Source:NASA
Comet Hale Bopp
WhatIs aStar?Image of the Sun from Goddard Space Flight Center
What is a Star?
Our Sun is the closest star.
At the simplest, a star is just a ball of gasthat has condensed out of interstellar material. The largest part of its lifetime is spent as a main sequence star during which hydrogen is being converted to helium balancing gravitational contraction so that the radius and energy output remain almost constant.
Source: The British Astronomical Association
Source: The British Astronomical Association
Our Sun is a star that has already spentabout 5 billion years on the main sequence.
Scientist believe our Sun is roughly halfwaythrough it's life.
Image courtesy of Dave DockeryAstronomical Society of Las Cruces Source: The British Astronomical Association
Nearby Stars:
Name Distance from Earth
Sun 93 million miles (8 light minutes) Proxima Centauri 4.22 Light YearsAlpha Centuri A,B 4.39 Light YearsBarnards Star 5.94 Light YearsWolf 359 7.8 Light YearsLalande 21185 8.3 Light YearsSirius A,B 8.6 Light Years
What is aLightYear?
Buzz Lightyear - Superhero
A Light Year is a unit of Distance,not time. It is the distance that light travels in one earth year, which works out to:
5,903,300,000,000 Miles
A Light Year is almost six trillion miles long!
That’s a long way! But even furtherThan most folks realize.
Compare this to a distant but familiarobject, Like Pluto.
Pluto is about 5 light HOURS from Earth.Only a small fraction of a light year
Pluto, as seen by theHubble Space Telescope
What is a
Star Cluster?Image by Dave Dockery
Astronomical Society of Las Cruces
Omega Centauri
Image by Dirk Langenbach
Star Clusters are collections of a few dozen to many thousands of stars, which are gravitationally bound.
Image by Dave Dockery
The Pleiades,an open cluster
Hercules Cluster,a globular cluster
WhatIs a
Nebula?North American Nebula,
Image by George Greaney
Reflection Nebula IC4592/4601 in Scorpius, byGeorge Greaney
A nebula is a cloud of gasand dust in space. Somenebulas are regions where new stars are being formed, others are the remains of dead or dying stars.
Source:NASA
Types of Nebula:
Emission Nebula
The Orion NebulaImage by Dave Dockery
Astronomical Society of Las Cruces
An Emission Nebula absorbs the light of nearby stars and reaches very high temperatures. Emission nebula are often found in regions of space where new stars are forming.
Source:NASA
Types of Nebula:
Reflection Nebula
The Pleiades Image by Dave Dockery
Astronomical Society of Las Cruces
A Reflection Nebula is a cloud of gas anddust which does not create its own light, but instead shines by reflecting the light from nearby stars.
Source:NASA
A planetary nebula is created when a star blows off its outerlayers into space, forming a nebulaIn the shape of a ring or bubble
Types of Nebula:
Planetary Nebula
The Dumbell Nebula Image by George Greaney Source:NASA
Dark clouds in space are called absorption nebulas or dark nebulas. An absorption nebula is a cloud of gas and dust which blocks light from the regions of space behind it.
Types of Nebula:
Absorption Nebula
The Horsehead Nebula
Image by George Greaney
The Andromeda Galaxy Image by Dave Dockery
Astronomical Society of Las Cruces
The term Nebula was first coined in the 19th century by Herschell, a famous astronomer, to distinguish anything in the sky that looked indistinct. Some of his'nebulae' turned out to be entire galaxies such as the Andromeda “Nebula“.
Illustration of Cygnus X-1 from the Astronomy Cafe
What is a Black Hole?
Source: The Berkeley Cosmology Group
What is a Black Hole?
Loosely speaking, a black hole is a region of space that hasso much mass concentratedin it that there is no way for anearby object to escape its gravitational pull.
Images from Hubble Space Telescope
What is a Quasar?
Illustration from the Astronomy Cafe
What is a Quasar?
Quasars are one of theMost mysterious and rareobjects in astronomy
A quasar is a very, Verybright object at the core of a few highly active galaxies. Quasars are thought to form as matter spins into super massive black hole at the center of these galaxies.
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