The
Hubble Space Telescope: Revolutionizing Remote-Distance Measurements
So how
do scientists today measure galactic velocities and distances?
Gathering velocities from a broad sample of nearby and faraway
galaxies is not that difficult--since the time of Edwin Hubble,
redshift analysis has been a handy tool for that purpose. Measuring
galactic distances, however, is another story.
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A
model of the Hubble Telescope
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Before
NASA launched the Hubble Space Telescope, ground telescopes
helped scientists determine the distance to some nearby galaxies
by measuring the brightness of certain parts of those galaxies.
But earth-bound telescopes could not make such measurements
for remote galaxies. This problem has been a significant stumbling
block, since scientists need to gather measurements from a wide
array of distant galaxies to compute a reliable estimate for
the age of the universe.
And thats
where the Hubble Space Telescope comes in.
Hubble
can accurately measure distances of galaxies as far as 108 million
light years away, far surpassing the distance-measurement capabilities
of ground telescopes. Hubble does this by measuring the brightness
of certain objects found in remote galaxies, including blinking
stars known as cepheids and exploded stars called type 1a supernovas.
Before
the Hubble Space Telescope mined this critical information from
remote galaxies, the limited galactic data available yielded
very rough estimates of the age of the universe. In fact, as
late as the early 1990s, estimates ranged widely between 10
and 20 billion years. In contrast, Hubble has allowed scientists
today to calculate their most accurate estimate ever--a range
between 12 and 16 billion years
.
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