Episode 17.
First Day of Summer

Question:

Key Points:

• The first day of summer on most calendars for 2019 is June 21st.
• The reason June 21st is labeled as the first day of summer is because it is the summer solstice
• The summer solstice is the day when the northern hemisphere is most tilted toward the sun
• Each year, as the earth revolves around the sun, the southern hemisphere tilts toward the sun, then northern hemisphere becomes tilted toward the sun and then it starts tilting back
• The Equinox is when the Earth is straight compared to the sun, or more accurately, if the line of the equator were to be extended into space then it woudl go through the sun
• These are considered the Astronomical seasons
• The reason we consider these the "begining" of spring is really because these are days that have been celebrated for thousands of years
• There is a Mayan temple which, only on the Equinox, makes the image of a serpent appear at sunset (I hadn't looked at the video before recording with the kids, only read a description, so it's actually a little less cool than I described to the kids)
• The Mayans, Greeks, and the Romans all existed in B.C. and all celebrated teh Solstices and Equinoxes.
• If you define summer as the time when the days are the longest and winter being the time when the days are the shortest, then the solstices would be the middle of the seasons
• For 2019, that would mean that summer would start on May 6th
• Meteorologists and Climatologists actually consider summer to be the three hottest months and winter to be the three coldest months: June, July, and August and then December, January, and February, respectively
• August is warmer than May (in the northern hemisphere) even though the Earth is tilted more in May than in August because it takes so long for the Earth to warm up or cool down
• There is an added benefit of defining the seasons by the days on the calendar because then there are always the same number of days in a season each year
• The summer solstice is between June 20th and June 22nd
• The next June 22nd summer solstice is not until 2203
• The spring Equinox is between March 19th and 20th
• It won't be on March 21st again until 2101
• There are actually 365.24... days in a year.
• Since it is not exactly 365.25, then every 100 years we do not have a leap year even though it is divisible by 4 (unless it is also divisible by 2000 years)
• The spring Equinox will be on March 19th every leap year and on March 20th every non-leap year from 2016-2048
• The first day of each season could be three different days, depending on how you define it
• We have a family tradition to get ice cream on the first day of summer (maybe you should do that too). Now, the kids want to go get ice cream on 3 different days

Video: