PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. •...

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PROFESSOR SMARTT’S Photo: NASA/Wikimedia commons Presented by

Transcript of PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. •...

Page 1: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

PROFESSOR SMARTT’S

Photo: NASA/Wikimedia commons

Presented by

Page 2: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

THE SUN AND OTHER STARSOur Sun is just one out of around 100 billion stars in our Galaxy, The Milky Way. On the clearest, darkest of nights, away from any light pollution, you can get a glimpse at just how many stars are out there.

Many of these have their own planetary systems, just like our Solar System.

You can’t see all 100 billion stars in our Galaxy with your own eyes. You can see about 4000 on any one night.

ESO/Y. Beletsky

Page 3: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

WHAT ARE STARS?

• Stars are giant balls of very hot gas.

• The gas is mostly hydrogen (70%) and helium (28%).

• The other 2% includes all the other elements in the periodic table.

• Stars are massive, they are trying to collapse under their own weight.

• But what keeps them up and what makes them so bright ?

Nasa

Page 4: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

• Stars are essentially giant nuclear reactors.

• Nuclear reactions in the centre of a star produce energy. This is when 4 hydrogen atoms combine together to give 1 helium atom.

• This reaction exactly balances the stars’ gravity, so they are (almost) perfect spheres.

• This needs very high temperatures, more than 14 million℃.

• Each nuclear reaction releases a tiny amount of energy, but it happens 1038

times per second in the Sun.Nasa

gravity

ener

gy

Page 5: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

OUR NEIGHBOUR: THE ALPHA CENTAURI SYSTEM

• Alpha Centauri is a Binary Star System, meaning it consists of two stars that orbit each other.

• Alpha Centauri A, also known as RigilKentaurus is similar in size, age and luminosity to our Sun.

• Alpha Centauri B, or Toliman, is slightly smaller and dimmer.

• There is also a third star, Proxima Centauri, which orbits around the two central stars. It is a red dwarf, 7 times smaller than the Sun, and is the closest star to our Solar System.

Alpha Centauri

Proxima Centauri(very faint!)

Credit : Wikipedia (large image), NASA, Hubble for inset

Page 6: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

ACTIVITYLet’s work out how long it would take us to get to our nearest neighbour star, Alpha Centauri.

Right: NASA’s Voyager 1 being loaded into itscapsule. The capsule was attached to a rocketfor launch, then the spacecraft emerged from itin space back in 1977. It is still travelling andhas reached the edge of the Solar System.

Page 7: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

How long would it take to travel to our nearest star?

First work out how long it takes Voyager 1 to travel 1 AU. Now work out how long it takes to travel 278,000 AU.

Do you think humans could ever reach our nearest star? Why?

You saw in the lesson that our nearest star is Proxima Centauri. It is at a distance of 4.2 light years from Earth. Let’s work out how long it would take a human made spacecraft to get there. Remember that this is the closest star to us in the Galaxy. The Galaxy is 10,000 times bigger than the distance between Earth and Proxima Centauri. These are very big numbers, let’s see if we can understand the scale of the distances between stars. We call the distance between the Earth and the Sun “1 Astronomical Unit”. It is actually 150,000,000 kilometres! But let’s call it 1 AU (where AU stands for Astronomical Unit).

The distance from the Sun to the edge of the Solar System is 130 AU. That is when we enter interstellar space. The space probe Voyager 1 was launched by NASA in 1977 and it took 36 years to reach the edge of the Solar System. Proxima Centauri is 278,000 AU from earth. How long would Voyager take to reach Proxima Centauri?

Sun Earth

1 AU

Page 8: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

THE SUN • Our star the Sun, is a 4.5 billion year old yellow dwarf. It is a

medium sized star, and just as we orbit it, it orbits the centre of our Milky Way galaxy.

• You could fit 1 million Earths into the Sun, if it were hollow.

• Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of a Red Giant, consuming Venus, Mercury and Earth. It will then shrink down to a White Dwarf, a star about the size of Earth. However, this won’t happen for another 5 billion years or so.

Page 9: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

BINARY STAR SYSTEMSYou may think of planets with two suns as a made-up idea from Star Wars, but in reality most star systems are like this. The Alpha Centauri system, and the fictional Tatooine system are just two of many.

Page 10: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

HOW STARS ARE BORN• A star begins its life in a cloud of dust

and gas. Large bits clump together, and start to collapse under the weight of their own gravity. This creates pressure on the core of the clumps, causing them to heat up and become Protostars, eventually they may get hot enough and large enough to become full stars.

• The leftover dust and gas will form the planets and asteroids of the system.

• We can see this happening all over the Galaxy.

NASA, ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team

Page 11: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

OBSERVATIONS OF A SOLAR SYSTEM FORMING

• This is an amazing image of a disk of gas and dust around a young star.

• This shows a solar system in the process of forming.

• The rings will condense into planets.

• This is about the size of our own Solar System (about 200 astronomical units across).

Page 12: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

T H E L A R G E S T S TA R S

There are stars called red supergiants that are much much larger than our Sun. The biggest known is VY Canis Majoris,2100 times bigger than the Sun. If we put it in the Sun’s place, it would extend past the orbit of Saturn!

Page 13: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

HOW STARS DIE • Eventually, stars will run out of fuel to convert into energy. When this happens, they collapse under the immense weight of their own gravity. If it is a large star (around 15 times the mass of the Sun), this collapse will trigger an explosion called a supernova.

• After the explosion, the supernova will shrink down into an object around the size of a city called a neutron star. These are the densest objects in the Universe – imagine fitting the mass of the entire human race onto a teaspoon!

NASA/CXC/SAO

Neutronstar

Page 14: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

ACTIVITY

Fill in the question sheet.

Page 15: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

The Sun and Other Stars

1. Approximately how old is the

Sun? a. 450 years old b. 2.5 million years old c. 4.5 billion years old

2. Name the star that orbits Alpha

Centauri A & B. a. Barnard’s Star b. Proxima Centauri c. Toliman

3. Fill in the blanks. What is it called

when a star, collapses under its own weight and explodes?

S _ P _ _ N _ _ A

4. VY Canis Majoris is _____ times the radius of the Sun.

a. 21 b. 210 c. 2100

5. VY Canis Majoris is _____ times

the mass of the Sun. a. 25 b. 250 c. 2500

6. True or false: Most solar systems have TWO or more stars.

True / False

7. What kind of star is our Sun? a. Yellow Dwarf b. Red Giant c. Neutron Star

8. What is the term for the release

of plasma that often follows a solar flare?

C _ R _ _ _ L M _ _ S E J _ _ T _ _ N

9. From 1 to 6, label the lifecycle of a massive star (one that is massive enough to explode) Some answers have been filled in for you.

Nebula 1 Star Supernova Protostar Red Super Giant Neutron Star 6

Score: / 8

Page 16: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

BONUS ACTIVITY

As a class, come up with some questions about the Solar System and tweet them to

Professor Smartt.

@smarttscience

Page 17: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

How long would it take to travel to our nearest star? Answers

First work out how long it takes Voyager 1 to travel 1 AU.

To travel 1 AU = 36 ÷ 130 = 0.28 years Now work out how long it takes to travel 278,000 AU.

To travel 278,000 = 0.28 x 278,000 = 77,840 years Do you think humans could ever reach our nearest star? Why? To get there in a human lifetime (70 years) we would have to send a spacecraft that is 1000 times faster than Voyager 1. That is currently beyond our capability, but perhaps in the future we will be able to.

You saw in the lesson that our nearest star is Proxima Centauri. It is at a distance of 4.2 light years from Earth. Let’s work out how long it would take a human made spacecraft to get there. Remember that this is the closest star to us in the Galaxy. The Galaxy is 10,000 times bigger than the distance between Earth and Proxima Centauri. These are very big numbers, let’s see if we can understand the scale of the distances between stars. We call the distance between the Earth and the Sun “1 Astronomical Unit”. It is actually 150,000,000 kilometres! But let’s call it 1 AU (where AU stands for Astronomical Unit).

The distance from the Sun to the edge of the Solar System is 130 AU. That is when we enter interstellar space. The space probe Voyager 1 was launched by NASA in 1977 and it took 36 years to reach the edge of the Solar System. Proxima Centauri is 278,000 AU from earth. How long would Voyager take to reach Proxima Centauri?

Sun Earth

1 AU

Page 18: PROFESSOR SMARTT’S · • You could fit 1 million Earths into the Sun, if it were hollow. • Eventually, when all of its hydrogen is burned, the Sun will swell up to the size of

The Sun and Other Stars

1. Approximately how old is the

Sun? a. 450 years old b. 2.5 million years old c. 4.5 billion years old

2. Name the star that orbits Alpha

Centauri A & B. a. Barnard’s Star b. Proxima Centauri c. Toliman

3. Fill in the blanks. What is it called

when a star, collapses under its own weight and explodes?

SUPERNOVA 4. VY Canis Majoris is _____ times

the radius of the Sun. a. 21 b. 210 c. 2100

5. VY Canis Majoris is _____ times

the mass of the Sun. a. 25 b. 250 c. 2500

6. True or false: Most solar systems have TWO or more stars.

True / False

7. What kind of star is our Sun? a. Yellow Dwarf b. Red Giant c. Neutron Star

8. What is the term for the release

of plasma that often follows a solar flare?

CORONAL MASS EJECTION

9. From 1 to 6, label the lifecycle of a massive star (one that is massive enough to explode) Some answers have been filled in for you.

Nebula 1 Star 3 Supernova 5 Protostar 2 Red Super Giant 4 Neutron Star 6

Score: / 8


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