“The first week of August hangs at the very top of the summer, the top of the live-long year, like the highest seat of a Ferris wheel when it pauses in its turning. The weeks that come before are only a climb from balmy spring, and those that follow a drop to the chill of autumn, but the first week of August is motionless, and hot… These are strange and breathless days, the dog days, when people are led to do things they are sure to be sorry for after.” — so begins the classic children’s book, Tuck Everlasting.
Images of panting dogs sprawled on the porch fill our minds. Miserably hot and humid, the Dog Days are the longest and hottest days of the year that happen to all of us, whether we have dogs or not! Depending on the latitude and the earth’s tilt, the Dog Days of Summer occurs between early July through mid August in the Northern Hemisphere and late January through early March in the Southern Hemisphere. With images of overheated dogs foremost in mind, I promise this unit study is not going to the dogs! Join us this month to learn about idioms and the history and science of the hottest days of the year.
Idioms are words or phrases that mean something different than their literal meaning and are commonly understood. Dog Days of Summer is a perfect introduction to idioms. Watch this fun YouTube® video with your children to learn the literal and figurative differences in idioms. Have children think of familiar idioms. This may be challenging for younger or concrete thinkers. A couple examples to start: raining cats and dogs, piece of cake, zip your lip. Many idioms are commonly accepted, although influenced by culture. Some may just sound odd. This is an excellent time to learn other expressions. Help your children understand idioms. Younger children may enjoy drawing. Ask children to draw the figurative and literal meanings of idioms. Older children may enjoy a rousing game of idiom charades! Short on ideas? Education First offers an extensive list to get you started!
Now let’s investigate our Dog Days, this idea is historically and scientifically rooted, tracing back to Ancient Times and refers to the constellation Canis Major’s brightest star, Sirius. Found in ancient Egyptian, Greek, and Roman records, the Egyptians welcomed Sirius when they observed the Nile River would rise when Sirius was visible just before sunrise. Ancient Egypt could not have existed without the great Nile. While most of Egypt was covered with sand, the Nile’s river basin boasted wildlife and fertile soils caused by the annual rise and fall of the Nile’s water levels. The inundation (or rising) would occur in July, filling the canals made by Egyptian laborers. In late October, the river receded. Water and rich silt deposits left afterward nourished the crops for the upcoming year. Crops were harvested in June before the return of the floods. Learn more about how the Nile River works here. Interestingly, the appearance of Sirius was not welcomed by ancient Greeks and Romans, who associated the star with droughts, disease and death. According to Greek mythology, Sirius was the dog of the hunter Orion. But it was the ancient Romans who placed the star in the constellation Canis Major. Fun fact: Sirius is mentioned in Homer’s Iliad! The Ancient Roman, Virgil, in the classic poem Aeneid, described the fiery Sirius as the “bringer of drought and plague to frail mortals, rises and saddens the sky with sinister light.” Not confined to ancient literature, the idea of hot, miserable dog days appears in Charles Dickens’ A Christmas Carol and other folklore stories through the centuries. Widespread honor was given in the 1817, Old Farmer’s Almanac, which proclaimed, “Dog Days are approaching; you must, therefore, make both hay and haste, while the Sun shines, for when old Sirius takes command of the weather, he is such an unsteady, crazy dog, there is not dependence on him.”
Prior to 1862, Sirius, a blue-white star, was seen as one star until a companion white dwarf star was discovered by telescope-maker Alvan Graham Clark. Sirius has a mass 2 times that of the Earth’s sun, making it 20x brighter than our sun, a yellow dwarf star. You may wonder why our sun appears brighter than Sirius. It’s all about distance. Sirius is nearly 8.6 light years (5+ trillion miles) past our sun!
Classifying stars takes many forms. The traditional color scale represents the temperature of the star. Typically, colors were used to identify stars as red, orange, yellow, white, bluish-white, and blue. The cool red star measures around 5,000° Fahrenheit. Our sun measures about 10,000°F. Blue stars are the hottest and may reach 200,000,000°F! Sirius is estimated at 18,000°F. With your younger children, check the temperature outdoors. How does it compare to the temperature of a star or the sun? While they will not fully grasp this difference, this is a casual way to introduce the idea. Take it further and use a Fahrenheit thermometer to check the temperature of your refrigerator and freezer. Compare them.
Introduce older children to the different temperature scales: Fahrenheit, Celsius and Kelvin. In the U.S., Fahrenheit (F) is the measurement of choice. The most common temperature scale throughout the world is Celsius (C), which sets the freezing point of water at 0 °C and the boiling point at 100 °C. Celsius is widely used in the scientific community. When it comes to scientific research, Kelvin is often the scale of choice because it does not use negative numbers. Encourage older children to convert the star temperatures from Fahrenheit to Kelvin using this excellent explanation.
As we settle into the dog days of summer, may we be thankful for air conditioning, cool water and that our home’s temperature is not that of the Sirius star for which the days are named! I hope this study has been a fresh breathe of air. I would love to hear from you. You can email me at dcrawford@rainbowresource.com.
