ASTRONOMY

1. ASTRONOMY

2. ASTRONOMY • Well, now that we have thoroughly covered the earth and its origins, let’s discover a bit about space.

3. ASTRONOMY • Since it is the most prominent feature of our solar system, let’s begin our discussion with the sun. • The sun is massive and actually makes up 99.8% of our solar system’s mass.

4. ASTRONOMY • As a result, the sun exerts enormous amounts of gravity on the objects which surround it. • This gravity causes a logical elliptical pattern of motion called an orbit.

5. ASTRONOMY • Now you may have already deduced that the sun does not have a solid surface. • It is actually a ball of hot gas all the way through. • About ¼ of the sun is made of Helium. • About ¾ of the sun is made of Hydrogen.

6. ASTRONOMY • However, the sun is sectioned off into layers. • The interior of the sun consists of a core, the radiation zone, and the convection zone.

7. ASTRONOMY • The core of the sun is where the energy of the sun comes from. • It is not burning any type of fuel, but rather giving off energy through nuclear fusion. • This is when hydrogen ions combine to form helium and that gives off energy.

8. ASTRONOMY • The total mass of helium is slightly less that hydrogen that makes it…the remaining mass is transformed into energy.

9. ASTRONOMY • The next layer of the sun is called the radiation layer. • This is a layer of very tightly packed gasses under extreme pressure in which energy is transferred in mostly electromagnetic radiation. • Because the layer is so tightly packed, energy can take over 100,000 years to pass through it.

10. ASTRONOMY • Finally, the outermost layer is called the convection zone. • As gasses reach the surface, they cool and sink once more to the core where the cycle begins again.

11. ASTRONOMY • Perhaps you’ve never thought this about the sun, but it actually has an atmosphere. • Its parts are the photosphere, chromosphere and corona.

12. ASTRONOMY • The photosphere as the name implies is the innermost sphere that gives off visible light. • Again, the sun doesn’t have a solid surface, but the gasses given off by the sun are dense enough to be visible.

13. ASTRONOMY • The chromosphere is the middle layer which gives off color. • Again, this is a word that can be broken into its Greek roots.

14. ASTRONOMY • Finally, the corona (which means “crown” in Latin) is the outermost layer of the thinnest gasses. • This stretches into space for millions of kilometers. • This creates thin streams of particles called the solar wind. • We’ll come back to those later.

15. ASTRONOMY • Over the decades as we have studied the sun, various features have exhibited themselves again and again. • Among them are sunspots, prominences and solar flares.

16. ASTRONOMY • Sunspots can look small to even the heavily telescoped eye, but in truth many are larger than the earth! • These are spots of gasses on the sun’s surface, which are cooler than those around them, thus they appear darker.

17. ASTRONOMY • The fact that these spots appeared to be moving stumped some scientists. • At last however, they realized that it is because the sun rotates on an axis just like the earth does!

18. ASTRONOMY

19. ASTRONOMY • Another feature is called a prominence. • This is when several groups of sunspots are linked by reddish loops of gasses.

20. ASTRONOMY • A solar flare is when those groups of sunspots SUDDENLY connect. • This releases a mass of magnetic energy which abruptly heats the gasses on the surface of the sun to millions of degrees Celsius. • This basically causes an eruption. • That eruption is a solar flare.

21. ASTRONOMY • Solar winds are basically electromagnetic particles from the sun that reach the earth. • Usually, the radiation is blocked by our atmosphere.

22. ASTRONOMY • But at the poles, the radiation can enter the atmosphere causing certain molecules to glow. • These glowing ribbons created by solar winds are calledauroras.

23. ASTRONOMY • However, there is a risk when this enters our atmosphere of a magnetic storm. • These can interrupt radio, TV and phone signals and even cause mass power outages. STORM MAGNETIC

24. ASTRONOMY • As we work our way our into the solar system, we will most certainly stumble upon planets. • Since they are vastly different from the others, we’ll discuss the inner planets first.

25. ASTRONOMY • Thefour inner planetsare small, dense and have rocky surfaces. • Because you could walk on their surfaces, they are called terrestrial planets. • The Latin word “terra” means Earth.

26. ASTRONOMY • Earth is very unique in many ways you already know about. • It consists of three layers; the core, mantle and crust. • It has an atmosphere which extends about 100km above the surface.

27. ASTRONOMY • But most importantly, Earth is the only planet able to support liquid water. • This is what makes life here possible for us.

28. ASTRONOMY • Let’s discuss a planet slightly more foreign. • Mercury is the innermost planet to the sun. • It is also the smallest terrestrial planet.

29. ASTRONOMY • Mercurywas studied by a probe called Mariner 10 in 1974 and 1975. • They found a crater laden, rocky surface which has not changed much over billions of years.

30. ASTRONOMY • Mercury has little to no atmosphere. • Due to this fact, temperatures fluctuate wildly on its surface ranging from 430⁰C in the day and -170⁰C at night. • That’s 806⁰F to -338⁰F!

31. ASTRONOMY • Venus is farther away from the sun, but it is far from cool. • In fact, on average, it is the hottest planet of them all! • Sometimes, Venus is called “Earth’s Twin”because of its similar internal structure. • However, Venus and Earth are VERY different.

32. ASTRONOMY • Venus is odd in that it takes about 7.5 months to rotate around the sun, but 8 months to revolve around its axis. • Thus, Venus’s day is longer than its year! • Also, it’s rotation on its axis is opposite ours. • Scientists believe Venus got smacked into reversal by some large object.

33. ASTRONOMY • Unlike Mercury, Venus has an extremely thick atmosphere. • It always appears cloudy there because of this and the greenhouse effect occurs due to heat being trapped. • This is why it is so hot…on average hotter than Mercury.

34. ASTRONOMY • It was discovered by the probe Magellan that Venus’s surface is covered by volcanoes and broad planes which were created by lava flow.

35. ASTRONOMY • After we bypass Earth, we reach Mars, the red planet. • It is red because of the iron rich rocks constantly oxidizing…otherwise known as rusting.

36. ASTRONOMY • Mars has an atmosphere of over 95% Carbon Dioxide. • It is much thinner than Venus’s atmosphere. • Mars is slightly smaller than Earth, but you could walkon its surface with proper equipment.

37. ASTRONOMY • The surface of Mars holds the most mystery and promise. • Scientists can see on the surface what appear to be canyons and features resembling coastlines. • This implies that perhaps Mars was once home to liquid water!

38. ASTRONOMY • However, that would have been at a time when its atmosphere was thicker and climate warmer. • Liquid water could not exist on Mars now. • There is frozen water on Mars which resides in ice caps closely resembling ours! • Some may also be frozen underground.

39. ASTRONOMY • Since Mars is tilted on its axis like us, it undergoes season changes like we do. • In Martian winter the ice caps grow and in Martian spring they shrink.

40. ASTRONOMY • Over the decades, many probes have explored Mars. • They found strong evidence that liquid water was once present and also that volcanoes were and are present. • The Martian Olympus Monsis the largest volcano in our solar system!

41. ASTRONOMY • The Outer Planets are much stranger than the terrestrial worlds. • These consist of four gas giants and the tiny Pluto.

42. ASTRONOMY • Jupiter as well as the other gas giantsare composed mainly of Hydrogen and Helium and have no solid surface. • However, they are MUCH larger than Earth and the other terrestrial planets.

43. ASTRONOMY • Despite their name gas giants have a core of mostly liquid Hydrogen and Helium. • This is due to the enormous pressure at the core of these planets. • Because of said pressure, the temperature is also much greater at their cores.

44. ASTRONOMY • Which of the gas giants has rings? • Actually, they all do! • A ring is simply a think disk of small particles of ice and rock. • Some are so thin, we can barely see them.

45. ASTRONOMY • Jupiter is the largest planet and the one with the most mass. • In fact, Jupiter’smass is about 2.5 times that of all the other planets put together!

46. ASTRONOMY • One of Jupiter’s most prominent features it its Great Red Spot. • The Hydrogen/Helium atmosphere contains a constant storm that, when viewed from space, appears as the spot.

47. ASTRONOMY • With no land mass to weaken the storm, it rages on. • It was first sighted in the 1600s and likely existed long before that. • By the way…The Great Red Spot is larger than Earth!

48. ASTRONOMY • Jupiterlikely has a (relatively) small dense core of rock and iron surrounded by a liquid mantle of hydrogen and helium. • Scientists believe this is true of all the gas giants.

49. ASTRONOMY • The pressure at Jupiter’s core is believed to be about 30 million times greater than Earth’s surface.

50. ASTRONOMY • Being so large, Jupiter has many moons. • Galileo discovered four of them which he named Io, Europa, Ganymede and Callisto. • We now have found 49 official (named) moons of Jupiter and another 14 which are still under consideration.