LESSON 2. Salient Features of the Sun

Sun- is the largest body in our solar system. - it is the nearest star to our planet. - it is only one of the many billions of stars in the galaxy and a typical main-sequence star.

Table 14.1: Data of the Sun

Distance 93 million miles

Diameter 864,400 miles

Volume 1,250,000 times greater than te earth

Mass 2 x 10 kg

Density 1.41 g/cm

Inclination 7 degrees - 10 degrees

Surface Temperature 6,000 degrees celsius

Equatorial 15,000,000 degrees celsius

Rotation Polar Once every 33 days

Equatorial Once every 25 days

Life span 11 billion years

Solar constant 1.94 calories/cm/min

Age 4.6 billion years

Type Yellow dwarf

The Sun's Atmosphere

- the most familiar sight as we observed the sun at early dawn or during sunset.

- it consists of four layers: photosphere, chromosphere, corona, and reversing layers.

Photosphere

- is the light sphere and the main body of the sun.

- this layer is 150 miles thick and with a temperature of 6,000 degrees celsius.

- this layer of the sun is characterized with various disturbances: granules, faculae, and sunspots.

1. Granules- are bubbles of hot gases that appear in cycles of bright and dark spots reaching up to 621 miles.

2. Faculae- (small torches) are small, but sharp eruptions which last for about 15 minutes to one hour.

3. Sunspots- are darker, cooler areas in the atmosphere. They range size from 800 to 80,000 km in diameter.

Chromosphere

- is the color sphere.

- it extends from 5,000 to 8,000 miles thick.

- when observed during total solar eclipse or with the use of an instrument.

- it appears in a rose pink in color.

- it also characterized with disturbances also referred to as "storms".

• Solar Flares- are gigantic eruptions that bombard the earth electromagnetic waves (X-rays, gamma rays, ultraviolet rays, infrared rays) and particles.

• they occur near sunspots and may spread up to 100,000 miles or more in space.

• The Electromagnetic waves reach Earth eight minutes after the initial burst.

• These waves cause interference in radio and telecommunication operations.

• The particles are the protons and electrons that are released from hydrogen atoms that are shattered to pieces.

- they are driven by the earth's magnetic field to the southern and northern hemisphere.

Aurora- the colliding with the particles of our atmosphere, causing the formation of brilliant displays of light.

- it is also purely electrical charges that look like neon lights in the sky that may last for days or weeks.

Prominences- are billowing arches of rose-colored flame, which also occur near sunspots.

- they may go up to about 500,000 to one million miles in space.

Corona- is the outer most layer of the sun's atmosphere.

- this layer is also visible only during solar eclipse.

- its shape varies with the eleven-year period of sunspots.

- its formed by the vapors emitted by the bubbling gases in the photosphere.

- the temperature of corona ranges from 1 to 2 million degrees celsius.

PLANETISIMAL THEORY

COMPANION STAR THEORY

NEBULAR HYPOTHESIS

Lesson 3: Characteristics of the Eight Planets of the Solar System• Eight planets revolve around the sun

with remarkable precision.• Speed, Eccentricity and Distance from

the sun characterize the orbits of the planets.

• Possibility of their crossing, allowing collision of planets and satellites to occur

- these are the numbers and variety of orbits in the solar system suggest this possibility.

• Mercury- has a small magnetic field.• Venus and Mars- have very weak

magnetic fields.• Earth- has a very significant magnetic

field.• Jupiter- has a very large and strong

magnetic field.• Warning process in the atmosphere of

Jupiter, Saturn, Uranus, and Neptune- is much similar to that of the earth, but their absorbing materials are different.

• Earth- is warmed by the heat developed in the absorption of ultraviolet rays by the ozone layer in the atmosphere while the outer planets are warmed by the heat developed by the absorption of solar radiation of methane and the smog of some particles.

• Jupiter, Saturn, and Neptune- are found to be emitting more heat than they receive from the sun

• Planets- are grouped according to size.

• Terrestrial planets- are small and they have high densities due to their bodies made up of rocks and heavy elements.

• Mercury, Venus, Earth, And Mars- are considered terrestrial planets.

• Jovian planets- are larger and massive and they have low densities and have dense atmospheres.

Characteristics of the Eight Planets of the Solar System

Planet Distance from the sun Inclination Rotation Revolution

Number of Satellite

Description

MERCURY 58 million km7 degrees14 minutes

About 58.7days

88 days 0Heavily cratered planet

VENUS 67 million miles3 degrees 39 minutes

243 days 225 days o Veiled planet

EARTH 93 million miles23 degrees30 minutes

24 hours 365 days 1 Blue planet

MARS 141,700,000 0 miles 25 degrees 1.37 1.88 years 2 Red planet

JUPITER 3 degrees 10 hours 19 Largest planet

SATURN 23Pale yellow,ringed planet

URANUS 1.79 billion miles 98 degrees 17.24 hours 84 years 5 Bluish-green with righs

NEPTUNE 30 degrees 14 hours 165 years 2Planet with a clear atmosphere

Lesson 4. Asteroids, Comets, and Meteors

• Asteroids- are small chunks of irregularly shaped objects that occupy the 350 million miles space between Mars and Jupiter.

• They orbit the sun in a belt following the same direction as those of the planets.

- the asteroid belt range in size.If all the asteroids were put

together they would form a body no more than 1,500 km in diameter.

•Their number is estimated to be about 30,000 but only about 7,000 have been identified..

•They vary in size, shape, color, and composition.

•A German astronomer Johan Bode accidentically discovered the existence of these miniature planets in 1800.

• Ceres- is the largest asteroids, 940 km in diameter.

Giuseppe Piazzi discovered it on January 1, 1801. Ceres was named after the Roman goddess of agriculture and also known as the protecting goddess of Sicily.

Pallas- is the second largest, 540 km in diameter.

Vesta- which is 510 km in diameter. About 500 other asteroids are

between 50 to 100 km in diameter and the rest are smaller than 50 km.

3 types of asteroids as their color and composition

•C-type asteroids- are very dark and carbonaceous. There are 75% of known asteroids.

•S-type asteroids- are rusty red in color and they are composed of iron and magnesium silicate.

•M-type asteroids- are rich with metallic substances.

3 types of asteroids according to position:

1.Athens- is the first type of asteroids.They lie near the orbit of Mars. Some examples are Ceres, Pallas, Juno, and Vesta.

2.Apollos- is the second type of asteroids. They lie near Jupiter and they have highly elliptical orbits. Eros, Geographos, and Icarus are examples. These asteroids constantly cross the earth's orbit.

Icarus reached the earth about 6 million km.

Geographos- reached the earth at a distance of about 9 km.

Eros- at about 485,000 miles. 3.Trojans- are the third type. They lie within the main asteroid belt and they circle the sun for 12 years.

Examples are Hector, Diomedes, Agamemnon, and Petrocius.

COMETS

it is known since ancient times.they were once associated to bad

omens and disaster.Oort Cloud- comet originated from

a dense shell of material surrounding the outer edge of the solar system.

Jan Oort- Dutch Astronomer.Comets- orbits are big and

elliptical.

•As they revolved around the sun some can reach the outer edge of the solar system and then back, moving closer towards the sun.

•As they get closer to the sun, they become very bright and start forming a tail.

3 Basic Parts of Comets

1. NUCLEUS- which is believed to be solid and composed of frozen gases, water vapor, and dust particles.

2. COMA- a cloudlike structure that surrounds the nucleus which is composed of gas and small bits of rocks and dust.

3. TAIL- that is composed of gas or dust particles or both. Comets may have one or several tails.

• When the comet is away from the sun, it has no tail.

• Comets appear in the sky from time to time.

• Some comets return on a cycle every few years.

2 Groups of Comets according to their order of appearance:

1. Short-period comets- have orbits that take less than 200 years.

2. Long-period comets- have orbits that take more than 200 years.

• Haley's comet appears every 76 years .

• Edmund Haley- predicted its appearance in 1910.

• The last time it reappeared was in 1986 and it is predicted to reappear again in the year 2062.

• Kuiper Belt Objects(KBO) - this is the name given to many

small bodies found orbiting the sun from beyond Neptune and Pluto.

• Oort Cloud- is a theoretical, spherical gathering of rocks at the outer edge of the solar system.

• Meteors- are the bright streak of light that dart the night sky which are referred to as "shooting star".

• In reality meteors are "space debris" or stray pieces of stony or metallic rocks that pass through the earth's atmosphere.

• Meteors travel in great speed that sometimes exceeds 100,000 miles per hour.

• Friction with the earth's atmosphere caused them to glow and vaporize completely in space.

• Meteorites- the large ones reach the earth's surface.

• Meteor shower- is a celestial event in which a number of meteors are observed to radiate from one point in the night sky.

- it is a regular sight sometime in the midmonth of August because in this month Earth crosses the path of comets and meteors are seen in the Esrth's atmosphere.

Summary in lesson 2;• The sun is the largest celestial body in the solar

system.It has a various characteristics.• The sun's atmosphere is the most prominent layer

that we see in the sky. The solar atmosphere consists of four layers: Photosphere, Chromosphere, Reversing layer, and Corona.

• The photosphere is characterized by disturbances. The most familiar to us are the sunspots.

• The chromosphere is likewise characterized by disturbances. The solar flares are disturbances that have profound effect on Earth's atmosphere.

Summary in lesson 3:

• The planets are classified according to size. The terrestrial planets are Mercury, Venus, Earth, and Mars, while Jovian Planets are Jupiter, Saturn, Neptune, and Uranus.

• The eight planets differ in terms of distance from the sun, rotation, revolution,inclination,and number of satellites.

Summary in lesson 4:

• Impact of asteroids larger than 500 meters on the earth's surface can cause global devastation. But this is an extremely rare phenomenon.

• Astronomers consider all three celestial objects as space debris.

• Comets have large and elliptical orbits and return on a predictable cycle of few years.

• Asteroids are chunks of irregularly shaped objects that occupy the space between Mars and Jupiter.

• Meteors are stray pieces of objects that appear in the night sky as shooting stars.

THANK YOU GEMINI FOR LISTENING!!!

"have a nice dayeveryone"...