Solar Events

1. Solar Events Eclipses, Sunspots, Solar Flares &Aurora Borealis

2. Moon Phases • New Moon, New Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, Old Crescent, New Moon (again) • New moon not seen just illuminated side facing away from Earth

3. Solar Eclipse • Only occurs in New Moon phase • If Moon’s shadow falls on Earth during this time, we see some portion of sun covered or “eclipsed” • Doesn’t happen once a month because moon’s orbit tilted at 5 degrees compared to Earth’s orbit around sun • At least twice a year, the geometry lines up and we get a solar eclipse

4. Umbra and Penumbra Umbra – Moon’s dark inner shadow, when strikes Earth we see total solar eclipse Penumbra – Moon’s faint outer shadow, when strikes Earth we see a partial solar eclipse Which one is safe to look at directly? Why?

6. Lunar Eclipse • Only occurs in Full Moon phase • Caused by the Moon traveling through some portion of the Earth’s shadow (two cones nested inside one another) • Penumbral /Outer Shadow is where Earth blocks some but not all of the sun’s rays from reaching the moon • Umbral/Inner Shadow is where Earth blocks all of the sun’s rays from reaching the moon

7. Penumbral Lunar Eclipse – Moon passes through Earth’s penumbral shadow, subtle and hard to observe Partial Lunar Eclipse – portion of Moon passes through Earth’s umbral shadow, easy to see Total Lunar Eclipse – entire Moon passes through Earth’s umbral shadow, Moon turns brilliant red through entire phases

9. Why a Red Moon? • While Moon completely within Earth’s shadow some indirect light still reaches the moon and illuminates it • Happens because Earth’s atmosphere bends/refracts the light • Earth’s atmosphere filters out the blue coloured light • Remaining light is deep orange/red

10. Sunspots • Dark areas on the surface of Sun (aka photosphere) • Areas have much lower temperature than surrounding area (drop as much as 2000C) • Can last for several hours or up to several months • Grouped in pairs with extremely intense magnetic fields (1000x stronger than Earth’s) • One region is negative (south) and other is positive (north)

11. Sun has been observed to have no sunspots and up to 200 at any one time

12. Solar Flares • Enormous explosions on surface of Sun that occur near sunspots • Caused by the release of built up magnetic energy in solar atmosphere • In minutes, heat material to millions of degrees celcius • Releases as much energy as a billion megatons of dynamite (10 million x greater than a volcanic eruption) • Types of energy release: radio waves, xrays, gamma rays, protons and electrons • Categorized by brightness

13. http://solarscience.msfc.nasa.gov/images/limb_flare.mpg

14. Effects on Earth • Usually has no effect on Earth because radiation filtered out by thick atmosphere • Has potential to zap satellites which could disrupt telecommunications • May have ability to make astronauts sick (radiation sickness) if exposed

15. Aurora Borealis • Caused by the collision of electrically charged particles from the Sun with gas particles in the Earth’s atmosphere • Colour produced dependent on types of particles that collide • Most common is yellowish-green produced by low altitude oxygen particles • Rare red colour produced by high altitude oxygen particles • Nitrogen particles produce blue or reddish-purple

17. Homework • Find an article on 2012 • Read and summarize • Bring both the article and your summary tomorrow ???? ????