Exam 2 Content: Telescopes and Solar Physics

Refracting telescope

Uses lenses to pass and focus light.

Reflecting telescope

Uses mirrors to bounce and focus light.

Aperture

Diameter of primary lens or mirror.

Focal length

Distance from lens/mirror to image.

Light-gathering power

Ability to collect more light for faint objects.

Photon collection

Total photons collected proportional to area.

Area formula

A = pi*r², where r is radius.

Largest visible light telescope

Diameter ~10m (>32 feet).

Angular resolution

Smallest angle details can be separated.

Resolution and diameter

Resolution inversely proportional to telescope diameter.

Atmospheric blurring

Caused by air movement affecting telescope images.

Seeing

Term for atmospheric blurring in astronomy.

Adaptive optics

Technique to correct atmospheric turbulence in real time.

Artificial star

Laser-created reference for measuring atmospheric turbulence.

Wavelength impact

Smaller wavelengths improve resolution of telescopes.

Eye as telescope

Eye collects light, focuses image on retina.

Poor angular resolution

Limited by small pupil size in the eye.

Telescope size limit

Atmosphere blurs images more than telescope resolution.

Image size relation

Longer focal length results in larger image size.

Fine details

Bigger telescopes can resolve more intricate details.

Real-time adjustments

Mirrors adjusted based on atmospheric changes.

Deformable Mirrors

Mirrors can be adjusted to reduce blurring.

Keck Telescopes

10m diameter mirrors located on Maunakea, Hawaii.

Mountaintop Telescopes

Built to minimize atmospheric interference.

Atmospheric Water Vapor

Interferes with infrared observations from ground.

Large Telescopes

Designed with diameters of 20-40 meters.

Segmented Mirrors

Used to save weight and cost in telescopes.

Space Telescopes

Not affected by Earth's atmospheric blurring.

Hubble Space Telescope

2.4m mirror; observes visible and infrared light.

James Webb Space Telescope

6.5m mirror; designed for infrared observations.

Radiation Blocked by Atmosphere

X-rays and gamma rays require space telescopes.

Radio Telescopes

Less sensitive to imperfections; made from metal.

Parabolic Dish

Reflector design used in radio telescopes.

Resolution Limitation

For telescopes >10" diameter, limited by atmosphere.

Sun's Radius

700,000 km, compared to Earth's 6,500 km.

Sun's Mass

2 × 10^30 kg, significantly larger than Earth.

Sun's Average Density

1400 kg/m³, less than Earth's 5500 kg/m³.

Sun's Surface Temperature

5800 K, much hotter than Earth's 300 K.

Sun's Composition

91% hydrogen and 8.7% helium by nuclei.

Sun's Energy Output

Luminosity measures energy radiated per second.

Thermal Emitter Spectrum

Sun's spectrum resembles ideal thermal emitter.

Sun's Rotation Period

25-31 days, longer at the poles.

Infrared Observations

Studying star and galaxy formation in space.

Luminosity

Total energy output of the Sun per second.

1 Joule

Energy to lift an apple 1 meter.

Solar energy received

Energy from the Sun reaching Earth per square meter.

1 AU

Average distance from Earth to the Sun.

Surface Area (SA)

SA = 4𝝅R² for a sphere.

Photosphere

Visible surface layer of the Sun.

Core

Site of nuclear fusion in the Sun.

Radiative zone

Energy moves via light, takes 170,000 years.

Convective zone

Energy moves via convection, takes about a week.

Opacity

Measure of how easily photons pass through matter.

Granulation

Pattern of bright and dark regions on the Sun.

Stefan-Boltzmann Law

Flux increases rapidly with temperature for blackbodies.

Thermal emitter

Photosphere emits light as a thermal emitter.

Chromosphere

Layer above photosphere, emits reddish hydrogen spectrum.

Convection

Hot material rises, cools, then sinks.

Energy transport

Movement of energy from core to surface.

Nuclear fusion

Process generating energy in the Sun's core.

Solar atmosphere

Layers above the photosphere, observable.

Energy transport efficiency

Convection is more efficient than radiation.

Hydrogen spectrum

Emission lines from hydrogen in the chromosphere.

Sunspots

Dark regions on the Sun's surface due to cooler temperatures.

Pressure balance

Pressure from temperature prevents collapse under gravity.

Chromosphere

Layer where solar color originates, appears red.

Solar Atmosphere

Temperature varies in outer layers of the Sun.

Density Gradient

Density decreases with distance from Sun's center.

Corona

Outer layer above the chromosphere, very hot.

Temperature Inversion

Higher temperature in corona than lower layers.

Corona Temperature

Ranges from 1 to 2 million K.

X-rays Emission

Corona emits X-rays, visible during solar eclipses.

Magnetic Field Tracing

Gas in corona follows Sun's magnetic field lines.

Core

Sun's center where nuclear fusion occurs.

Radiation Zone

Energy transported via photons in the Sun.

Convection Zone

Energy transported by boiling motions in the Sun.

Sunspots

Dark spots on Sun, cooler than surrounding areas.

Galileo's Observation

First observed sunspots, challenging classical views.

Magnetic Field Dynamics

Sun's magnetic field connects to ionized gas.

Sunspot Temperature

Sunspots around 4500 K, cooler than photosphere.

Stefan-Boltzmann Law

Relates temperature to emitted radiation intensity.

Sunspot Cycle

11-year cycle of rising and falling sunspot numbers.

Prominences

Large loops of solar material, up to 100,000 km.

Solar Flares

Explosive bursts on Sun's surface, last seconds to minutes.

Coronal Mass Ejections

Large outflows of solar material associated with flares.

Solar Wind

Particles escape Sun at 400-800 km/sec.

Space Weather

Solar activity affects Earth's atmosphere and technology.

Solar Wind

Stream of charged particles from the Sun.

Auroras

Glowing skies caused by solar particles.

Magnetosphere

Earth's magnetic field protecting from solar particles.

Hydrostatic Equilibrium

Gravitational force balanced by outward pressure.

Energy Density

Energy per unit mass; nuclear is higher than chemical.

Proton-Proton Fusion

Fusion process combining protons into helium.

Einstein's Equation

E=mc²; mass-energy equivalence principle.

Coronal Mass Ejections

Large expulsions of plasma from the Sun.

Photosphere

Sun's visible surface layer.

Chemical Energy

Energy from chemical reactions, nuclei intact.

Nuclear Fission

Energy release from splitting heavy nuclei.

Neutrinos

Neutral particles with very little mass.

Positron

Antimatter counterpart of the electron.