1. How Hot is that? Comparing different sources of Thermal Energy across the Universe

2. Our Common Experience  We can all sense differences in temperature by holding our hands near an object.  We can even make rough comparisons (hotter or cooler?)  But to compare many things accurately, we use tools  Thermometers (bulb, bimetallic, digital probe, etc.)  Temperature scales (Celsius, Kelvin, Fahrenheit)  These help us to quantify.

3. Typical Comparisons  Celcius – a temperature scale with 100 degrees between freezing and boiling points of water, with zero at water’s freezing point  Water freezes at 0 o C  Water boils at 100 o C  Kelvin - a temperature scale with 100 degrees between freezing and boiling points of water, with zero at “Absolute Zero”  Water freezes at 273 K  Water boils at 373 K(or 0 K)  Absolute Zero – where all particle motion stops… has never been reached  But Scientists have come within a nanokelvin in the lab!

4. Temperature Changes in Earth’s Atmosphere  The atmosphere has different layers  Different density  Composition  Temperature  Temperature profile

5. Our Local Extremes  Local weather records for Massachusetts …  Hottest: 41.7 o C Chester and New Bedford, 8/2/1975 (314.9 K )  Coldest: -35 o C Chester, 1/12/1981 (238.2 K)

6. Earth Extremes  World weather records  Hottest air temperature: 58 o C at El Azizia, Libya on September 13, 1922 (331.2 K)  Hottest surface temperature: 70.0 o C in Lut Desert, Iran (343.2 K)  Coldest air temperature -89.6 o C in Antarctica on July 21, 1983 (185.6 K)  Other areas claim to be more extreme, but these are the official records  The interior of the Earth is hotter, hot enough to melt rock and metallic minerals, but only is seen at the surface of erupting volcanoes, so…

7. Beyond Earth…  Within our Solar System…  The Moon: 107 o C on sunlit side, -153 o C on dark side (which is 380.2 K and 120.2 K)  Hottest Planet: Venus +400 o C (673 K)  Coldest Planet: Neptune -201 o C (72.2 K)  Hottest thing in our Solar System? The Sun! At around 5500 o C on its surface, but as hot as 15 million o C in its core. (Kelvin measure would be 5778 K and 15,000,273 K respectively)

8. Beyond our Solar System…  Molecular clouds 20 K  Betelguese a giant Red Star 3,500 K  Sol (our Sun) 5,778 K  Rigel, a supergiant Blue Star 11,000 K  Stellar Mass black holes accretion disk 10,000,000 K  Quasars 30,000,000 K

9. When its hot…its hot! And, when its not, its not. The End