comprehend the milky way galaxy and the sun’s place in it comprehend the four components of the...
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Comprehend the Milky Way Galaxy and the Sun’s Place In It
Comprehend the Four Components of the Galaxy
Comprehend Other Planetary Systems
Comprehend Black HolesComprehend the center of the
Milky Way Galaxy
The Milky Way Galaxy
Lesson OverviewThe Milky Way Galaxy and the Sun’s Place In ItThe Four Components of the GalaxyOther Planetary SystemsBlack HolesThe Center of the Milky Way Galaxy
The Milky Way and our SunThe Sun is one of
about 200 billion stars that make up the Milky Way Galaxy
Diameter ranges from about 100,000 to about 160,000 light-years
The Shape of the GalaxyStars are arranged in a wheel-shaped disk
that circles around a bulging center Sun is about one-third to one-half of the way out
from the galaxy’s center
Andromeda, a Galaxy Similar to the Milky Way Almost everything you
can see in the sky is in the Milky Way Galaxy
Andromeda is visible in the autumn sky as a fuzzy patch
The Four Components of a Galaxy 1.The Galaxy Disk
A galaxy disk is the large, flat part of a spiral galaxy, rotating around its center
Contains individual stars, clusters of stars, and almost all the gas and dust found in the galaxy
2. The Central Region of the Galaxy
The nuclear bulge is a spiral galaxy’s central region
Milky Way Galaxy’s nuclear bulge is about 2,000 parsecs, or 6,500 light-years, in diameter
Packed more densely with stars, dust, and gas than any other part of the galaxy
The Four Components of a Galaxy
3.The HaloGalaxy’s halo is the
outermost part of a spiral galaxy, nearly spherical and lying beyond the spiral
A globular cluster is a spherical group of up to hundreds of thousands of stars, found primarily in a galaxy’s halo
The Four Components of a Galaxy
4.The Galactic CoronaBeyond the galaxy’s halo lies
the galactic corona, or outer halo
Scientists don’t know what the corona consists of, but think it may include small black holes, cool dwarf stars, large numbers of neutrinos, and other exotic particles
The Four Components of a Galaxy
Other Planetary SystemsThe Obstacles to Discovering
Exoplanets: It’s hard to see planets
around other stars by direct observation
In the infrared, the brightness of a planet peaks, while that of a star declines. This makes it easier to spot
Black Holes A black hole is an object
whose escape velocity exceeds the speed of light
Escape velocity is the speed at which an object must travel to “escape” a star’s gravity
How Scientists Detect Black Holes:Because the gravitational field near a black hole
would be so strong, any matter nearby would orbit very fast
This hot material would radiate energyIt would appear as an X-ray source
Black Holes
The Center of the Milky Way Galaxy To observe the galactic nucleus,
scientists use wavelengths in the infrared/radio part of the spectrum or in X-rays and gamma rays
The massive-black-hole hypothesis seems to be the best explanation for the energy source in the Milky Way Galaxy and other similar galaxies
Comprehend the Milky Way Galaxy and the Sun’s Place In It
Comprehend the Four Components of the Galaxy
Comprehend Other Planetary Systems
Comprehend Black HolesComprehend the center of the
Milky Way Galaxy
The Milky Way Galaxy