Science day 1

What is a scientific theory?

A scientific theory is a well-tested explanation of how or why something happens in nature, supported by lots of evidence.

What are the three things a scientific theory must be able to do?

1. Explanation for things we observe in nature

2. Provides strong evidence for that explanations

3. Be testable and be falsifiable

How do scientific theories help scientists understand the universe?

They help scientists explain how the universe works, connect different observations, and predict what they might discover next.

Units for Measuring Distances in Space

1. Astronomical unit (AU)

• Definition: The average distance between Earth and the Sun.

• Used for: Distances within our solar system.

Example: Earth is about 1 AU from the Sun

2. Light-year (ly)

• Definition: The distance light travels in one year on earth

• Used for: Distances between stars and galaxies.

Example: Proxima Centauri, the nearest star beyond the Sun, is about 4.24 light-years away.

What is shown in the Electromagnetic Spectrum?

It shows all types of electromagnetic radiation arranged by wavelength or frequency.

What is radiation?

Radiation is energy that travels through space or matter as waves or particles.

What are similarities and differences of each region of the electromagnetic spectrum?

All electromagnetic waves:

• Transfer energy.

• Travel at the speed of light in a vacuum.

They differ in wavelength, frequency, energy

What are the levels of hazardousness for different types of radiation?

• Radio waves, microwaves, infrared: Generally not harmful; intense exposure can heat tissue.

• Visible light: Usually safe at normal levels, but very bright sources can damage eyes.

• Ultraviolet: Can damage skin

• X-rays and gamma rays: damage cells and DNA.

• Gamma rays: extremely hazardous

Describe each type of orbit

1. Geostationary orbit

• Above the equator.

• Takes about 24 hours to orbit Earth.

• Appears to stay over the same location.

• Used for communications and weather monitoring

2. Low Earth orbit (LEO)

• Relatively close to Earth.

• Usually takes about 90–120 minutes to orbit.

• Used for Earth imaging

3. Polar orbit

• Passes over or near both poles.

• Earth rotates beneath the satellite, allowing it to observe different areas.

• Used for mapping and environmental monitoring.

Differentiate between a natural satellite and an artificial satellite

Natural satellite: A naturally occurring object that orbits another object, such as the Moon orbiting Earth.

Artificial satellite: A human-made object placed in orbit, such as a weather satellite.

Describe at least 4 examples of how satellites help us on Earth

Weather forecasting: Track storms and hurricanes.

Communication: Support television, phone, and internet services.

Navigation: GPS helps people find locations and directions.

Earth observation: Monitor wildfires, deforestation, ice melt, and pollution.

Explain why space junk is a problem and how it can be solved

Space junk is old satellites, broken pieces of spacecraft, and other human-made debris orbiting Earth.

Why is it a problem? Debris travels very quickly and can damage working satellites or spacecraft when they collide.

Solutions: Track debris, working on space junk removal using claws and grappling systems

Compare the wavelengths and energies of red light and blue light.

Red light: Longer wavelength and lower energy.

Blue light: Shorter wavelength and higher energy.

Explain red-shift and blue-shift regarding the electromagnetic spectrum.

Redshift: Light shifts toward longer wavelengths, indicating that an object is moving away from us.

Blueshift: Light shifts toward shorter wavelengths, indicating that an object is moving toward us.

This is the Doppler effect applied to light.

Describe the sound you would hear when a train blows its horn as it passes by you.

The horn sounds higher-pitched as the train approaches and lower-pitched as it moves away. This is the Doppler effect for sound.

What can the spectral lines from stars and galaxies tell us? Explain how this works.

Spectral lines help scientists learn about stars and galaxies. Each element has its own unique pattern of light, like a barcode.

Scientists compare these patterns to known elements to find out what stars and galaxies are made of.

By studying how the lines change, scientists can also learn an object's temperature, speed, rotation, magnetic fields, and distance.

How are spectral lines used to measure the velocity of moving stars?

Scientists compare the observed spectral lines with their normal wavelengths.

• Shift toward red → moving away.

• Shift toward blue → moving toward us.

• A larger shift generally indicates a higher speed along our line of sight.