Really Big Show : Interrupt your scheduled programming. A drama is about to unfold in the nighttime skies.

If the new fall TV season lineup has you down, October is definitely the time to look up.

October’s planets will surprise San Fernando Valley residents with more dramatic scenes than many weekly television series and, at the same time, help you learn how to identify these celestial bodies during one of the few times of the year when they can be seen together.

The best sky show is actually a miniseries airing just after sunset Thursday and next Friday, when the moon makes a guest appearance in an area of sky featuring three planets: Mercury, Venus and Jupiter.

On Thursday night, the moon can be seen above Mercury, about level with Venus and below Jupiter. Next Friday, the moon is positioned above all three planets.

These two nights present a rare opportunity to spot the elusive planet Mercury. To find Mercury, use a pair of binoculars (7 x 50 power) or a six-inch-diameter or larger telescope, and find a viewing site with a clear, flat western horizon. Look for Mercury before it sets shortly after sunset.

Without a telescope, Mercury will look like nothing more than a faint star. If you fail to spot it, try again Oct. 31, about 40 minutes before dawn, when it is easily visible near the bright star Spica.

Because Mercury and Venus are between the sun and Earth, we are able to see them only near sunrise and sunset.

As the closest planet to the sun, Mercury is also the swiftest, circling the sun every 88 days. Because of the gravitational tug of the sun, Mercury rotates on its axis only every 58 days. As a result, there are 1 1/2 Mercury days in every Mercury year.

But although it is the closest planet to the sun, Mercury is not the hottest. That honor belongs to Venus, easily spotted below the moon on Thursday as the brightest object in the sky.

With a thick blanket of carbon dioxide making up its atmosphere, Venus lets in light but does not let it out, creating a greenhouse effect that has, over billions of years, raised its temperature to a blistering 878 degrees Fahrenheit.

Like Mercury, Venus and the other planets shine not because they are generating heat, but because of the sunlight reflected off their surfaces.

With a small telescope, you can see Venus’ crescent phase as it begins its passage between the sun and Earth in mid-November. Follow Venus from the beginning of the month with a telescope to see how the crescent phase disappears as it descends into the glare of the sun.

The next brightest object in the sky Thursday is the planet Jupiter, still showing the effects of the collision of Comet Shoemaker-Levy 9 in July. The dark, Earth-sized impact zones on the planet’s hydrogen cloud tops may still be visible with a small telescope, and may remain so for a year.

Even though it is the largest planet in the solar system, 11 times the diameter of the Earth, Jupiter will appear smaller in a telescope than Venus. Yet four of its 13 known moons, known as the Galilean satellites, should be visible with only a pair of binoculars.

If you prefer getting up early to see morning shows, check out Mars about 2 a.m. Oct. 17 and 18, when the planet passes through the Beehive Cluster in the constellation Cancer.

A collection of a few hundred stars 500 light years away, the Beehive will appear like a sparkling backdrop of jewels through a pair of binoculars or a small telescope. Mars will blaze a brilliant red.

Mars’ color stems from the iron-rich dust on its surface that has, in essence, rusted. Mars is also home to Olympus Mons, the solar system’s largest volcano.

Using a telescope in the coming months, observers may be lucky enough to observe Mars’ north polar cap begin to “melt” during that planet’s spring season. But don’t look for any rivers or streams emanating from the cap--the frozen surface there is carbon dioxide, or dry ice, which is actually evaporating into the atmosphere.

But the greatest guest star of all this month is the planet Saturn, whose own appearance will change more during the next year than a character actor’s.

Saturn is high in the southeast after dusk, appearing in the faint stars of Aquarius. Visible all this month and the rest of autumn, Saturn’s rings are tilting in respect to our plane of sight, a process that occurs every 15 years.

By 1995, Saturn’s rings will appear edge-on, making them virtually disappear from our view on Earth.

As a result, this fall is one of the last times this year that you will be able to catch Saturn’s rings through a small telescope.

Since the planets constantly change position and appearance as they revolve around the sun during the year, the show never ends.

So when your favorite television show becomes a repeat in the spring, grab a star chart from Sky and Telescope or Astronomy magazines and look for the new season of planets on the celestial channel--commercial free, of course.