Astronomy Fundamentals (Explained Like I'm 5)

What Are the 9 Planets?

In Vedic astrology, we use 9 "planets" (we call them navagraha in Sanskrit, which means "nine graspers"). Here's the lineup:

1. The Sun ☀️

Wait, the Sun is a planet? Not in real life — it's a star! But in astrology, we call it a "planet" because it moves across the sky from Earth's point of view. It takes about 365 days (one year) to go around the zodiac. That's why it moves about 1 degree per day.

2. The Moon 🌙

The Moon is Earth's satellite (like a little buddy orbiting around us). It's the fastest-moving "planet" in astrology, zooming through the zodiac in about 27 days. That means it changes signs every 2–3 days!

3. Mars

Mars is the red planet. It takes about 2 years to go around the zodiac. Mars moves at a medium speed.

4. Mercury

Mercury is the closest planet to the Sun. It's a speedy little planet, taking only 88 days to orbit the Sun. But here's the weird part: from Earth, Mercury often looks like it's going backward (we call this "retrograde"). Don't worry — it's an illusion, like when you're in a car and another car looks like it's moving backward.

5. Jupiter

Jupiter is the biggest planet in the solar system. It's a slow mover, taking almost 12 years to go around the zodiac. That means it stays in each sign for about a year.

6. Venus

Venus is the bright, shiny "morning star" or "evening star" you sometimes see in the sky. It takes about 225 days to orbit the Sun, but like Mercury, it often looks like it's moving backward from Earth.

7. Saturn

Saturn is the slowest planet in traditional astrology. It takes almost 30 years to go around the zodiac! That means it stays in each sign for about 2.5 years. Saturn is like the wise old grandparent of the planets.

8. Rahu (North Lunar Node)

Rahu is not a real planet. It's a mathematical point where the Moon's orbit crosses the Sun's path. Think of it like an invisible crossing point. Eclipses happen when the Sun or Moon gets close to Rahu or Ketu. Rahu takes about 18.6 years to go around the zodiac.

9. Ketu (South Lunar Node)

Ketu is the opposite point from Rahu — always exactly 180 degrees away. If Rahu is at 15° Aries, Ketu will be at 15° Libra. Like Rahu, it's a mathematical point, not a physical object.

Fast vs. Slow Planets

Here's a simple way to remember how fast they move:

• Super Fast: Moon (changes signs every 2–3 days)
• Fast: Mercury, Venus, Sun (days to months)
• Medium: Mars (~2 months per sign)
• Slow: Jupiter (~1 year per sign)
• Very Slow: Saturn (~2.5 years per sign), Rahu/Ketu (~1.5 years per sign, moving backward)

Why does speed matter? Fast planets represent quick, day-to-day stuff (like your mood or what you're thinking about today). Slow planets represent long-term themes (like your career path or life lessons).

Three Ways to Describe the Sky

Heliocentric means we describe the solar system from the Sun's point of view. Geocentric means we describe it from Earth. Topocentric means we describe it from your exact spot on Earth.

Astrology usually cares about the Earth-based view because that's the sky people actually experience. When exact local timing matters, topocentric positions can be even more specific.

Why We Look at the Sky from Earth

Astrology uses a geocentric perspective, which is a fancy way of saying "we look at the sky from Earth's point of view." We know that Earth orbits the Sun (that's what science tells us), but astrology cares about how things appear to us on Earth. That's why the Sun and Moon are called "planets" — they're part of the moving sky from our perspective.

What's Next?

Now that you know what the planets are physically, you can learn what they mean symbolically. Check out Planetary Symbolism (ELI5) to see what each planet represents (like love, wisdom, discipline, and ambition). You can also open the Basics hub to see every published beginner guide in one place.