We find that Taurus ruled the Zodiac;
Two thousand less, and Aries lead the host;
But Pisces now, by virtue of its post.
Each constellation in two thousand years
Advances one sign eastward, it appears.
The Precession of the Equinoxes will
In twenty-and-five thousand years fulfil
A grand cycle of the ages—some epochs end —
Some worlds burn up—some changes vast impend.
And gave their beauty and their secret laws ?
Inlaid the heavens with wheeling worlds of light,
To chant His praise, and beautify the night ? •
Who made the Sun and Planets in their course,
And keeps them there, by universal force ?
Who made the Earth, the mountains, sea and air,
The seasons too, and all their products rare ?
All beasts and fowls and living things we see,
And all mankind ? who made both you and me ?
The great "I Am !" He also gave His Son ;
Believe His Word, and by His love be won.
Barred spiral galaxies are comprised of a disk that has the vast majority of
stars in the galaxy, and a bar-shaped bulge at the center that also contains
a large concentration of stars. In Earth’s night sky, the disk of the galaxy
stretches all the way around the sky and is about as wide as an outstretched
hand. If one looks up at it with the unaided eye, it appears as a starry stream
of light stretching from one side of the sky to the other. Ancient Chinese
astronomers called this band of light the “Silver River,” while ancient Greek
and Roman astronomers called it a “Road of Milk” (Via Lactea). This was
translated into English as the “Milky Way.” When astronomers realized that
we live in a galaxy, the name Milky Way was used to refer not just to this band
of stars, but also to the entire galaxy.
How do we know Earth’s magnetic field can flip upside down?
In 1906 French physicist Bernard Brunhes (1867–1910) found rocks with
magnetic fields oriented opposite to that of Earth’s magnetic field. He proposed
that those rocks had been laid down at a time when Earth’s magnetic
field was oriented opposite to the way it is today. Brunhes’s idea received support
from the research of Japanese geophysicist Motonori Matuyama (1884–
1958), who in 1929 studied ancient rocks and determined that Earth’s magnetic
field had flipped its orientation a number of times over the history of our
planet. Today, studies of both rock and the fossilized microorganisms imbedded
in the rock show that at least nine reversals of Earth’s magnetic field orientation
have occurred over the past 3.6 million years.
The exact cause of the polarity reversal of Earth’s magnetic field is still
unknown. Current hypotheses suggest that the reversal is caused by Earth’s
internal processes, rather than external influences like solar activity.
Who was Foucault and how did he come up with the idea for his pendulum?
Jean-Bernard-León Foucault (1819–1868) was a leading scientific figure of
his time. Aside from his famous pendulum, Foucault also invented the
gyroscope, made the most accurate measurement of the speed of light up to
that time, and instituted improvements in the design of telescopes. In addition,
Foucault was a prolific writer, producing textbooks on arithmetic, geometry,
and chemistry, as well as a science column for a newspaper.
Together with physicist Armand Fizeau (1819–1896), Foucault was the
first person to use a camera to photograph the Sun. The camera they used was
a daguerreotype, which took pictures on a light-sensitive, silver-coated glass
plate. These early plates were barely sensitive to light, compared to the film
or digital detectors being used today, so to take their photos, Fizeau and Foucault
had to leave the camera focused on Earth for quite a while. It took so
long that the Sun’s position relative to Earth would change considerably, and
the pictures would be blurry. This problem inspired Foucault to invent a pendulum-
driven device to keep the camera in line with the Sun.