Punto della situazione

andrea_ch, 05/05/2010 8.19:

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Articolo preso dal numero di febbraio di Practical Astronomy (www.practicalastronomy.com) di cui sono fiero collaboratore

Astronomy History: The Last 50 Years 1960-2010
By Dr. David Mannion

As we start the second decade of the 21st Century,
I thought I would look back at the
last 50 years of astronomy from 1960 to 2010.

Go back to 1960 and we see that most
astronomy was done in the optical region of the
electromagnetic spectrum.
The largest telescope was the Hale (200 inch or
5.08 metre) telescope. 
Neutron stars/Pulsars
had not been discovered, nor had Quasars or
any evidence of black holes.
The Universe in infrared, ultraviolet, x-ray and
gamma-ray was completely unknown.

The Cosmic
Microwave
Background (CMB),
which is the leftover
remnant of the
primordial fireball
that decoupled from
matter 380 000
years after the Big
Bang, was not
discovered until
1965.

These microwave
observations
changed the debate
on how our Universe
began, between
Steady State
advocated by Fred
Hoyle and the Big
Bang theory. 

The Big Bang theory
easily explained the
CMB and the
amounts of the
elements seen today, especially hydrogen,
deuterium, helium and lithium.
Opening Up Other Wavelengths
In the 1970s, we saw the growth of telescopic
observations from all parts of the
electromagnetic spectrum, using satellites as
platforms for larger and larger space
telescopes. 
Thus UHURU, SAS II, IRAS,
Einstein opened these wavelengths that cannot
be seen through the Earth’s atmosphere.
Using Hubble’s Law v = H0 D where v = speed
of a galaxy in km/ s and D = distance to the
galaxy in millions of parsecs, one can work out
the age of the Universe.
As Hubble’s constant was between 50 and 100
km s-1 Mpc-1, then the age of the Universe
was between 10 and 20 billion years old.
This was the case throughout the 70’s and 80’s.


Hubble Space Telescope

The Hubble Space Telescope (HST) with a 2.4m
mirror, was launched in 1990. This has led to an
unprecedented leap
in our understanding
of the whole
Universe.

The ultra deep field ( it.wikipedia.org/wiki/Hubble_Deep_Field ) shows a
region a few square
arc minutes of sky,
with over 10 000
galaxies. If you
multiply that for the
whole sky, one
counts over 100
billion galaxies!

From 1990 to 2010
Infrared telescopes
have shown the
birthplaces of stars.
Ultraviolet
telescopes show the
regions around
extremely hot, type
O and B
supergiants.
X-rays emitted by accretion discs around
neutron stars and black holes, have been
imaged.
Gamma-ray telescopes detect the most
extreme events like GRBs, where neutron stars
and black holes collide.
I now turn to the new astronomies using
Cosmic Ray, Neutrino and Gravitational Wave
detectors. 

These are the latest windows in
astronomy, allowing us to detect particles like
protons, that have 10 million times the energy
of the particles colliding in CERN.
The neutrino telescopes in the late 1980s saw
the supernova SN1987A that was 168 000 light
years away in the Large Magellanic Cloud.
Gravitational wave observatories like LISA in
2018, will detect gravitational waves produced
by orbiting binary systems.
Thus at the dawn of optical astronomy in
1609/1610, we see that Galileo dismantled the
Ptolemaic ideas that had lasted 1600 years,
with the 5 planets, the Moon and the Sun,
orbiting a stationary Earth.
350 years later in 1960, we knew the Universe
might be between 10 and 20 billion years old.
And now in 2010, where we have found over
420 exoplanets, we believe that the Big Bang
occurred 13.7 +/- 0.1 billion years ago and
have three space probes, twice the distance
from the Sun than Pluto is!

Insomma, da Hubble e con l'avvento dell'osservazione "non visuale" l'astronomia è stata completamente rivoluzionata.

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