Content

• To step
• Part 1 of 3: Observing the external features
• Part 2 of 3: Observing celestial bodies
• Part 3 of 3: Recognizing factors that limit the visibility of celestial objects

The night sky is full of light, most of which comes from celestial objects such as stars and planets. If you cannot tell whether a celestial body is a star or a planet, then you can learn how to distinguish the outer features of these two celestial bodies and when to view them best.

To step

Part 1 of 3: Observing the external features

1. Check if the object is flashing. One of the easiest ways to distinguish between stars and planets in the night sky is to see if the object is blinking (or shimmering). This can usually be seen with the naked eye if you have a clear view of the sky and if you look at the sky long enough.
   • Stars twinkle and glitter - hence the song "Twinkle Twinkle Little Star".
   • Planets do not glitter. They have a constant brightness and general appearance in the night sky.
   • When you look through a telescope, planets can appear to "wobble" around the edges.
   • Any object that blinks, twinkles, or shimmers is likely a star. However, if it moves quickly across the night sky, it could also be an airplane.
2. Notice whether the object rises and sets. Celestial bodies are not fixed to the night sky. All celestial bodies move, but the way they move can be a good indication of whether they are stars or planets.
   • Planets rise in the east and set in the west. They follow a similar path to the sun and moon.
   • Stars move around in the night sky, but they don't rise or set. Instead, they revolve around Polaris (the North Star) in a circular pattern.
   • If the celestial body you see appears to be moving in a more or less straight line across the night sky, it is most likely a planet.
   • Satellites also move across the night sky, but do so much faster than planets. A planet can take hours or even weeks to cross the night sky, while a satellite can cross the entire sky in minutes.
3. Recognize the ecliptic. Planets are always found along an imaginary belt in the night sky, the ecliptic. This belt is not actually a visible object, but careful observation will help you find the place where celestial objects converge.While stars can also be seen along this invisible belt, you should be able to distinguish them by their sparkle.
   • Of the celestial bodies along the ecliptic, Mercury, Venus, Mars, Jupiter, and Saturn are significantly brighter than the surrounding stars. This is due to the proximity of the sun, because their "brightness" is reflected sunlight.
   • The easiest way to find the ecliptic is to view the location and orbit of the sun and moon in the sky relative to your location on Earth. The path of the sun in our sky is very close to the path of planets along the ecliptic.
4. Observe the color. Not all planets are colorful. However, many of the most prominent planets in our night sky appear to have a certain color. This can help distinguish the planets from stars. While some people with exceptionally good vision are able to see a subtle color variation, that coloration usually falls within the blue-white to yellow-white range. For most people, stars are white to the naked eye.
   • Mercury is usually gray or slightly brownish in color.
   • Venus appears pale yellow.
   • Mars usually appears somewhere between pale pink and bright red. This is influenced by the relative brightness of Mars, which varies over a two-year cycle.
   • Jupiter is orange with white bands.
   • Saturn is usually light gold in color.
   • Uranus and Neptune are light blue. However, they are usually not visible to the naked eye.
5. Compare the relative brightness. While both planets and stars light up the night sky, planets are usually much brighter than many stars. Astronomers measure the relative brightness of celestial objects using the astronomical magnitude scale, with most planets falling within range of objects visible to the naked eye.
   • Planets reflect the bright light of our solar system's sun, which is relatively close to Earth. Stars, on the other hand, radiate their own light.
   • While some stars are much brighter and larger than our sun, these stars are much farther from Earth than the planets in our solar system. Because of this, the planets (which reflect the light from our sun) usually appear brighter from Earth.

Part 2 of 3: Observing celestial bodies

1. Use star charts and planet guides. Whether you have poor night vision or simply have no idea where to find certain celestial objects, a map or guide can help you determine where to look. You can buy star charts and planet guides from a bookstore, print free guides from the Internet, or download a star / planet guide on your smartphone.
   • Remember, star charts are usually only valid for a limited period of time (usually about a month). That's because the position of stars in the sky changes over time as the Earth progresses in its orbit.
   • If you are consulting a star chart or planetary guide in the field, make sure to use a muted red flashlight. These flashlights are designed to give light without your eyes having to constantly adjust to the dark.
2. Buy a good telescope or binoculars. If you cannot see enough celestial objects with the naked eye, consider using a telescope or binoculars. These tools can help you improve your vision by enlarging the area you are looking at. This can make visible objects more obvious and can even make objects invisible to the naked eye visible.
   • Some experts recommend familiarizing yourself with the night sky with the naked eye, then trying binoculars, and finally using a telescope. This can help you get used to the visible celestial bodies and their place in the night sky.
   • Compare telescopes and binoculars online before investing. Read reviews written by people who own a particular model by searching online for the model you are interested in.
3. Go to a location with no light pollution. Light pollution from urban areas can drastically limit your ability to see celestial objects in the night sky. To really improve visibility, you can go to a location where you are not bothered by light pollution. These designated sites have been designated by the International Dark-Sky Association (IDA) as places worthy of protection from encroaching light pollution and urban development.
   • Common locations without air pollution are regional parks and national parks, but other dark sky locations are surrounded by well-lit, more densely populated regions.
   • Check the IDA website to find a light-pollution-free location near you.

Part 3 of 3: Recognizing factors that limit the visibility of celestial objects

1. Check if an occultation will occur. An occultation is when the moon passes between the Earth and a particular star or planet, obstructing the visibility of that celestial body. These obstructions are somewhat frequent and can be easily calculated because they occur predictably.
   • Occultations may be visible from some locations on Earth and not visible from others. Check in advance whether an occultation is known and whether it significantly affects the visibility of celestial objects.
   • You can learn about planned occultations by searching online or by consulting an astronomical guide. The International Occultation Timing Association publishes their forecasts online for free.
2. Learn to recognize the moon phases. Light reflected from the moon can limit your ability to see stars and planets. When the moon is almost full, observing celestial objects can be difficult. For this reason, it is better to check the current moon phase before stargazing.
   • If you are unsure of the current moon phase, you can consult an online moon phase guide for free. On the website of the United States Navy, you can view the moon phases by date, calculated in advance to the year 2100.
3. Find the right conditions. If you know how to distinguish stars and planets from each other, you will not get far if the starry sky is not clearly visible. Your ability to see celestial bodies can be limited by a number of factors, both man-made and natural phenomena.
   • Light pollution is one of the biggest limiting factors for the visibility of the night sky. If you live in or near a metropolitan area, you will likely need to travel to a more rural area to see more stars and planets.
   • A skyscraper and a lot of snow can both affect the view of the night sky. When it is very cloudy or there is a lot of snow, it can be difficult to see celestial objects.
4. Avoid other limiting factors. There are many other factors that can also affect the visibility of the night sky, including some that you can control yourself. For example, your alcohol consumption, smoking, and pupil dilation at the time of viewing can all affect your ability to see celestial bodies. These factors all affect your eyes' ability to adapt to the dark and see stars and planets in the night sky.