Seasonal ScienceAfter a mostly mild winter, the signs of springtime rebirth are starting to be seen across the United States. Depending on where you live, you may already be seeing some telltale signs: migratory birds returning, trees beginning to bud, or crocuses peeking through the last of winter's snow. Maybe you've noticed a few extra minutes of daylight, or a change in how you feel, or even in how you dress.
Whatever you've been seeing or feeling recently may be explained by one important annual event: The arrival of spring, which officially began in the United States last Wednesday, March 20, at 2:16 p.m. EST.
If you live in the Northern Hemisphere, the vernal equinox (or spring equinox) ushers in spring. The equinox is one of two days of the year — the other, the autumnal equinox, is in fall — when Earth's orbital path passes through the celestial equator. (To picture the celestial equator, imagine Earth's equator extending like a plane off into space.) With the beginning of spring and continuing into the summer months, the sun is above the celestial equator.
As Earth revolves around the sun, its axis remains at a nearly constant angle of about 66.5° relative to the plane of Earth's orbit around the sun. Earth's northern axis always points at the northern celestial pole, which is currently near the star Polaris (the North Star). With the sun above the celestial equator, the Northern Hemisphere begins to "tilt" toward the sun, thereby receiving more of the sun's energy, giving us more daylight hours and gradually increasing temperatures.
Celebrations of spring were born of Earth's natural cycles of light and darkness, of life and death. Ancient cultures took note of the change in seasons and made offerings to their local gods to receive blessings for the year.
The first month of the Babylonian new year, Nisan, started on the vernal equinox. The mid-March timing of this month corresponded with the beginning of the agricultural cycle (cultivating, planting, harvesting). At this time, offerings of the first fruits were made to the gods, especially the goddess of fertility, Ishtar. In addition, a festival held at this time reestablished the monarchy and determined the destiny of the people for the coming year.
Ostara — the goddess of fertility in many ancient cultures — signified rebirth, balance, new beginnings, and growth. She was pictured holding an egg in one hand while rabbits — a common symbol of fertility in ancient European cultures — play at her feet. According to legend, a rabbit laid golden decorated eggs at Ostara's feet in order to please her. Sound familiar?
Some ancient cultures used myths to explain the different seasons because they didn't have scientific explanations for such significant events:
- The Greek myth "Demeter and Persephone"
explains spring another way. The story goes that it was always
spring in the world before Hades, god of the underworld, kidnapped
Persephone, daughter of Demeter, goddess of the harvest. Demeter
suffered greatly when Persephone disappeared and roamed Earth
looking for her. She was so angry she blamed the land for Persephone's
disappearance and stopped everything from growing.
Eventually, Demeter discovered Persephone's whereabouts and arranged for her release. However, Persephone's release was conditional: she could only be released if she had not eaten anything while she was in the underworld. Unfortunately, Persephone had eaten a few pomegranate seeds, thereby ensuring her return to Hades for part of the year. When Persephone is reunited with her mother, the Earth flowers and blooms as a sign of Demeter's happiness. However, when Persephone returns to the underworld, Demeter retreats into her lonely shell, and Earth is dormant and cold.
- A Native American legend "The Spring Beauty" tells the story of a young man, Seegwun, the spirit of spring, and his encounter with old Peboan, the spirit of winter. When Peboan breathes, the "streams stand still," while Seegwun shakes his hair to make warm rains fall and flowers bloom. As their meeting continues, Seegwun's warmth takes over, and Peboan melts away.
Celebrating Spring Today
Traditional spring festivals and holidays
are still celebrated around the world.
Easter
Easter celebrates the Christian belief in the resurrection
of Jesus Christ. The holiday is central to the Christian year and
dates back to earliest Christianity. The spring equinox is used
to determine the date of Easter. Easter is the Sunday after the
first full moon after the vernal equinox and can fall anytime between
late March to early April.
The early Church used the Julian calendar to set the date of Easter, although there were several problems with the calendar, which caused Easter to fall closer to the summer. As a result, Pope Gregory XIII made changes to the calendar to ensure that Easter would always fall in the spring.
- Read about the history of the calendar in the Riverdeep Current archive article "Not Just Another Day."
The word "Easter" is derived from Ostara's name. English and German are among the only languages that use this derivation for the name of the holiday. Many other languages, including French, Spanish, and Italian use some variation of pasach, Hebrew for "pass over," for the holiday's name.
Passover
Passover, which occurs in the middle of the Hebrew month
of Nisan, is one of Judaism's most important festivals. In ancient
times, the holiday coincided with the spring harvest, and was a
pilgrimage festival (one of three times during the year when all
men were required to participate in celebrations at the Temple).
Later on the holiday commemorated the Exodus from Egypt in the 13th
century B.C.
At a special meal, the Seder, celebrants retell the story of the Jews leaving Egypt with readings from a special prayer book (the Haggadah), sing joyous songs, and eat special foods, such as matzoh (unleavened bread), hard-boiled eggs, and parsley. To remember the haste with which the Jews fled Egypt, no products containing yeast are eaten during the entire holiday.
Many Jews clean their houses thoroughly for Passover. In some areas, there is a custom of wearing new clothes, giving gifts, and buying new household and other kitchen items in advance of the holiday. Passover lasts for eight days.
Holi
The Hindu festival of Holi is celebrated on the full-moon
day of the spring equinox and is sometimes known as the "festival
of color." In ancient times the holiday was connected to the wheat
harvest.
The holiday recalls the evil goddess, Holika, Prince Prahlad's aunt. Holika, who was immune to fire, tried to destroy the prince by burning him in a fire. But through divine intervention, Prahlad escaped and Holika died. Before her death, Holika asked for forgiveness, and Prahlad decreed that her name would be remembered once a year. Some interpretations claim that the holiday celebrates the defeat of winter (in the form of the demon Holika).
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Chinese New Year
The Chinese New Year is also known as the "Spring Festival,"
and although it occurs at the midpoint between the winter solstice
and the vernal equinox (anytime between early- to mid-February),
there are many customs similar to other cultures. People buy new
clothes and may exchange gifts. Special meals and foods may be eaten,
and there is the custom of thoroughly cleaning one's house (sweeping
away the old), and settling arguments and debts.
- Read the Riverdeep Current archive article "Long Life and Prosperity" for more information about the traditions related to Chinese New Year.
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The
Role of Light in Photosynthesis Follow changes in the rate of photosynthesis over a period of one day in this Middle School Science Gateways activity. |
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The
Effect of Temperature For high school students: Find out how temperature affects photosynthesis with this Biology Gateways activity. |
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You
Light Up My Life How does light — or its absence — affect how we feel and behave? Find out in this Riverdeep archive article. |
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