How do they know what stars

are made of?Waves

Spectrography

Planet X

The Earth

Waves

• Wavelength(λ): distance between consecutive crests

• Frequency (f): number of oscillations per second

• v = λ·f

• c = λ·f (electromagnetic wave)

fhE

cf

Electromagnetic spectrum

Electromagnetic spectrum

Electromagnetic spectrum

Spectrography

• White light is

made up of all the

colors of the

visible spectrum.

• Passing it through

a prism separates

it.

Non white light

• By heating a gas or

with electricity we

can get it to give off

colors.

• Passing this light

through a prism

does something

different.

Emission & absorption spectra

continuous spectrum

absorption spectrum

emission spectrum

hot source

gas

Bohr model

• Electrons exist only in orbits with specific amounts of energy called energy levels

• Therefore…– Electrons can only gain or

lose certain amounts of energy

– Only certain photons are produced

– Energy of photon depends on the difference in energy levels

1

23

45

6

nucleus

Hydrogen spectrum

A B C D E F

Lyman series (UV)

A B D E

Balmer (Visible)

A B C D

Paschen (IR)

E1

E2

E3

E4

E5

E6

Ene

rgy

IRregion

UVregion

656 nm

486 nm

434 nm

410 nm

ionization

Planet X

• What are planet X atmosphere made of?

Hydrogen

HelioHelio

Helium

Planet X

• What are planet X atmosphere made of?

Sodium

HelioHelio

Carbon

Planet X

• What are planet X atmosphere made of?

Chlorine

HelioHelio

Oxígeno

Planet X

• What are planet X atmosphere made of?

Nitrogen

HelioHelio

Oxygen

The Earth

• Which is the Earth atmosphere spectrum?

Nitrogen

HelioHelio

Oxygen

Earth 1

The Earth

• Which is the Earth atmosphere spectrum?

Nitrogen

HelioHelio

Oxígeno

Earth 2

The Earth

• Which is the Earth atmosphere spectrum?

Nitrogen

HelioHelio

Oxygen

Earth 4

The Earth

• Which is the Earth atmosphere spectrum?

Nitrogen

HelioHelio

Oxygen

Earth 3