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Why Can I See Some Planets in the Sky and Not Others? 

Why can I see some planets in the sky and not others? 

Do you love looking up at the wondrous display of stars in the sky on a clear night? If so, you may be amazed to find out that, if you look closely at the right time, you can spot some planets too—and without even needing to use a telescope! Let’s find out how with the help of our friends at Moon Phases.

Even though planets are far away in space, many of them are visible at night during certain times. Mercury, Venus, Mars, Jupiter, and Saturn are called the “bright planets” because they are the five brightest planets and can be seen with the human eye. 

Over the course of days and weeks, these planets appear to change position against the starry sky, and they go through phases where they are visible from Earth. Their visibility is determined by the interaction of light from the sun and the planets’ own shadows. Sometimes these planets become visible just after it begins getting dark. Other times, they can only be seen very late at night. When they get too close to the sun, they aren’t visible at all. Since one or more of these planets may be hidden near the sun at any point in time, it may be several months before you can claim to have seen all of them.

How do you distinguish these planets from the stars? 

  • These planets are typically as bright as—or even brighter than—the brightest of stars! 
  • They tend to appear steady, whereas stars have a twinkling appearance. 
  • Since they are closer to the earth, you can see a disk rather than a tiny dot.

What about Uranus, Neptune, and Pluto? According to Sky Tour, these three other planets are trickier to see and identify.

  • Uranus is difficult to distinguish because its brightness is similar to that of many stars. It is easier to see with a small telescope or binoculars.
  • Neptune is much fainter than Uranus and can usually be seen in a dark sky with a telescope.
  • Pluto can’t be seen in small telescopes and is even difficult to spot with larger telescopes.

You can find out about the current positions of the planets in magazines like Astronomy and Sky and Telescope

Once you become more familiar with the sky, you’ll be able to identify planets in the blink of an eye! 

Did you know about the Venus and Jupiter sky-watching event happening on August 28? Mark your calendars now and read more about this fascinating event here!

Looking for more Never Stop Asking "Why?" questions? Catch up on all of the past "Why's" on the blog!