The Old Farmer's Almanac 2015 (11 page)

13

The universe is expanding, but no one knows how far. It has no outside or edge. The extent of the known
universe
is 38 to 47 billion light-years in every direction.

14

When observed in desert skies far from any city, there seem to be millions of
stars
visible to the naked eye. (The naked eye limit is about magnitude 5.8.) However, the actual number is about 2,600. You could count every star in 20 minutes at a leisurely rate of about two per second.

15

Then
uclear fusion
that produces the Sun’s heat and light occurs in its innermost quarter, a tiny “sun within the Sun.” The surface we see is merely where the energy escapes.

16

The largest storm in the known universe is Jupiter’s
Great Red Spot
, a hurricane that is three times the width of Earth and floats 5 miles above Jupiter’s surface.

17

Galileo was the first person to see
Saturn’s rings
, but his telescopes were so poor that he believed to his dying day that the rings were attached handles, like those on a teacup.

18

In addition to white, stars are colored red, orange, blue, violet, yellow, brown, even black. The single missing hue is
green.

19

The fastest twirling objects in the universe are
pulsars
(tiny stars). Since 1982, some 200 have been discovered. The fastest-spinning of these turns 716 times per second. (The second fastest spins 641 times per second.) From a pulsar’s surface, other stars would appear not as dots but as white lines in the sky.

20

The first of a new type of celestial object—
asteroids
—was discovered on January 1, 1801.

21

Neptune has the strongest
winds
in the solar system. Its air howls at 1,300 miles per hour, four times faster than Earth’s fiercest tornadoes.

22

The universe’s second most abundant element,
helium,
is the only one that never freezes solid.

23

Half of the Moon is composed of a single element, the same one that makes up two-thirds of your body weight:
oxygen
.

24

After the Moon is struck by a
meteoroid
or falling spacecraft, it vibrates for hours.

Bob Berman
is the director of Overlook Observatory in Woodstock and Storm King Observatory in Cornwall, both in New York.

The
Calendar
[>]
pages are the heart of The Old Farmer’s Almanac. They present sky sightings and astronomical data for the entire year and are what make this book a true almanac, a “calendar of the heavens.” In essence, these pages are unchanged since 1792, when Robert B. Thomas published his first edition. The long columns of numbers and symbols reveal all of nature’s precision, rhythm, and glory, providing an astronomical look at the year 2015.

Why We Have Seasons

The seasons occur because as Earth revolves around the Sun, its axis remains tilted at 23.5 degrees from the perpendicular. This tilt causes different latitudes on Earth to receive varying amounts of sunlight throughout the year.

In the Northern Hemisphere, the summer solstice marks the; beginning (if summer and occurs when the North Pole is tilted toward the Sun. The winter solstice marks the beginning of winter and occurs when the North Pole is tilted away from the Sun.

The equinoxes occur when the hemispheres equally face the Sun. At this time, the Sun rises due east and sets due west. The vernal equinox marks the beginning of spring; the autumnal equinox marks the beginning of autumn.

In the Southern Hemisphere, the seasons are the reverse of those in the Northern Hemisphere.

The Left-Hand Calendar Pages •
[>]

The Left-Hand Calendar Pages contain sky highlights, daily Sun and Moon rise and set times, the length of day, high tide times, the Moon’s astronomical place and age, and more for Boston. Examples of how to calculate astronornical times for your location are shown below.

A SAMPLE MONTH

SKY WATCH
The box at the top of each Left-Hand Calendar Page describes the best times to view celestial highlights, including contunctions, meteor showers, and planets. The dates on which select astronomical events occur appear on the
Right-Hand Calendar Pages
[>]
.

1.
To calculate the sunrise time for your locale: Note the Sun Rise Key letter on the chosen day. In the
Time Corrections
[>]
table find your city or the city nearest you. Add or subtract the minutes that correspond to the Sun Rise Key letter to/from the sunrise time given for Boston.

Use the same procedure with Boston’s sunset time and the Sun Set Key letter value to calculate the time of sunset in your locale.

2.
To calculate the length of day for your locale: Note the Sun Rise and Sun Set Key letters on the chosen day In tine
Time Corrections
[>]
table find your city. Add or subtract the minutes that correspond to the Sun Set Keyletter to/from Boston’s length of day. Reverse the sign (minus to plus, or plus to minus;› of the Sun Rise Key letter minutes. Add or subtract it to/from the first; result.

3.
Use the Sun Fast column to change sun- dial time to clock time. A sundial reads natural, or Sun, time, which is neither Standard nor Daylight time. To calculate clock time on a sundial in Boston, subtract the minutes given in this column; add the minutes when preceded by an asterisk [*]. To convert the time to your city, use Key letter C in the
Time Corrections
[>]
table.

Attention, Readers:
All times given in this edition of the Almanac are for Boston, Massachusetts, and are in Eastern Standard Time (EST), except from 2:00
A.M.
, March 8, until 2:00
A.M.
, November 1, when Eastern Daylight Time (EDT) is given.

4.
This column gives the degrees and minutes of the Sun from the celestial equator at no on EST or EDT.

5.
This column gives the approximate times of high tides in Boston. For example, the first high tide occurs at 7:45
A.M.
and the second occurs at 8:30 P.M, the same day. (A dash indicates that high tide occurs on or after midnight and is recorded on the next day.) Figures for calculating high tide times and heights for localities other than Boston are given in the
Tide Corrections
[>]
table.

6.
To calculate the moonrise time for your locale: Note the Moon Rise Key letter on the chosen day. Find your city in the
Time Corrections
[>]
table. Add or subtract the minutes that correspond to the Moon Rise Key letter to/from the moonrise time given for Boston. (A dash indicates that the moonrise occurs on or after midnight and is recorded on the next day.) Find the longitude of your city in the
Time Corrections
[>]
table. Add a correction in minutes for your city’s longitude.