ASTR 1P01 Lecture : Solstices

• School: Brock University
• Department: Astronomy
• Course: ASTR 1P01
• Professor: Bozidar Mitrovic

Document Summary

The first day of summer (around june 21st) The first day of winter (around dec. 22) At our latitude july as hotter than june and january is cooler than december. Thermal invertia: it takes some time for the water masses to warm up or cool down (70% of the earth"s surface is covered with water) The earth"s rotational axis precesses (wobbles) once every 26,000 years. As a result of this pressesion the north celestial pole moves relative to the stars. This was detected first by hipparcus between 146 bc and 130 bc. The calendar is adjusted over time so that the vernal equinox is always around march 20. Thus, in 13,000 years the summer solstice will be also around june 21 but the stars that we would see opposite to the sun ( at midnight) would be very different from those that we conserve now. This can have an effect on weather.