CELESTIAL MOTION AND CELESTIAL SPHERE – notes

Phases of the Moon - depend on where the moon is in its orbit around the Earth

New Moon rises and sets with the Sun
Full Moon rises at sunset and sets at sunrise

First Quarter phase rises at noon and sets at midnight

Last Quarter phase rises at midnight and sets at noon

Waxing crescent phase sets just after sunset; it is out most of the day and you don’t see it. It is in the direction of the Sun but a little to the left of it

Waning crescent phase rises just before sunrise; it is out most of the day and you don’t see it. It is in the direction of the Sun but a little to the right of it

Gibbous – can be waxing (growing bigger) or waning (getting smaller) – this phase is mainly seen at night and either a few hours before sunset in the east - or a few hours after sunrise in the west. It is the phase that occurs before and after the full moon

ZENITH – the point in the sky on the celestial sphere that id directly overhead.

ALTITUDE – the angular distance above the horizon

AZIMUTH – directional bearing around the horizon measured in degrees from north
(0 degrees)

MERIDIAN – a great circle passing through the celestial north and south poles and through the zenith of any location on Earth

ecliptic – apparent line path through the 12 constellations of the zodiac that the Sun seems to take in one Earth year - also representing the “edge” of the plane of the Earth’s orbit.

constellations of the zodiac – the 12 patterns recognized by several ancient civilizations as the background for the Sun, the Moon and the planets.

SUN AND EARTH’S MAGNETOSPHERE NOTES

Sun is PLASMA – an electrically- magnetically charged gas.
70% Hydrogen, 20% helium and 2% heavier elements
Sun is a madhouse of electromagnetic activity
On the Sun, almost everything is electrically conductive because there aren’t very many intact neutral atoms. Overwhelming thermal and radiation energies excite electrons to the point at which they pop off their atoms, creating a seething stew of positively charged nuclei and free negative electrons – this gaseous mix that conducts electricity as good as copper wire is called PLASMA.

Like any electricaly charged object, plasma produces magnetic fields when it moves. As those fields shift, they induce more currents, which in turn produce more fields. This tangle of plasma and electric and magnetic effects determines the forms of nearly everything in or above the Sun, such as the bright coronal loops and the dark areas we call sunspots. Everything we see as solar activity is a magnetic field being acted upon by plasma and vise-versa. Both are forever in motion.

The magnetic field drives virtually everything on the Sun. Sun has opposite north and south magnetic poles like the Earth. The Earth’s field is produced by motion of the molten iron in the outer core The Sun’s field is produced by the internal motion of plasma. Until recently, imposible to see beneath the photosphere. Helioseismology developed – an ultrasound scan on the Sun’s interior. Global Oscillation
Network Group (GONG) – worldwide array of observation stations positioned 60-degrees apart to observe the Sun 24-hours a day. The idea came about in the 60s – observed that solar surface throbbed with rhythmic oscillations like the skin of a drum. Discovery: Much faster rotation at equator than at poles. The “shear zone” (a.k.a. – tacholine) between the regions of varying rotations is what is believed to cause the magnetic field.

The internal motion stretches and twists the north-south magnetic field lines, wrapping them around the Sun thus adding energy (imagine how energy is stored in a stretched rubber band). Sometimes the powerful twisted field lines become buoyant and rise above the photosphere – these manifest as loops, prominences and sunspots, which are observed on the surface of the Sun.

SOLAR FLARE – A sudden eruption of energy on the solar disk, lasting minutes or hours, in which energy and particles are released. A small area above the solar surface suddenly roars to tens of millions of degrees, throwing off a surge of radiation that can cause communication blackouts, disable satellites, or kill a spacewalking astronaut.
CORONAL MASS EJECTION - billions of tons of charged particles escape from the sun’s halo, the corona, at millions of miles per hour. When these behemoth clouds slam into the Earth’s protective magnetosphere, they squash magnetic field lines and dump trillions of watts of power into the Earth’s upper atmosphere. This can overload powerlines, causing massive blackouts, and destroy delicate instruments on anything in Earth’s orbit.

SOLAR WIND - A tenuous flow of gas and energetic charged particles, mostly protons and electrons (plasma) -- which stream from the Sun; typical solar wind velocities are almost 350 kilometers (217 miles) per second.

MAGNETOSPHERE – Outer portion of the Earth’s - or any planet’s atmosphere - in which the magnetic
field interacts with the solar wind.

WHAT EXPLAINS FLARES AND THE CORONAL MASS EJECTIONS THAT ARE RESPONSIBLE FOR ELECTRICAL TEMPESTS ON EARTH? HOW CAN THESE STORMS BE PREDICTED?

The corona produces the most powerful particle accelerators in the solar system – flares and CMEs. Flares expel much of their energy as x-rays and are genrated when electrical currents are suddenly released as one or more magnetic field loops in the corona become strained to the breaking point and snap into a new shape. This radiation reaches the earth in 8 minutes and can disrupt radio communications and navigation systems. A small percentage of flares hurl out fast-moving, high-energy protons that can cripple satellites. CMEs often follow flares. These massive eruptions of plasma can also occur on their own. CMEs take 1-3 days to reach Earth. They smash into the Earth’s magnetosphere and deform it – and if conditions right – produce a multi-million ampere ring current in the belts of charged particles that continually circle the Earth.

CMEs are even more threatening to communication satellites than flares and can take out power grids causing power failures. The trigger mechanism for CMEs is not known, therefore not possible to predict. With SOHO, et.al., we can see these storms leaving the Sun. The magnetic polarity of a CME can change during its journey. If the polarity is opposite that of the Earth’s, it does the most damage on impact. We can predict with 80-percent accuracy if they will hit the Earth. The worst storms often come in the waning years after the solar maximum. The most recent solar max. ended in 2001; the strongest x-ray flare ever observed was in Nov. 2003