Night Sky Basics
Everything to get started observing with the naked eye.
Being comfortable and prepared can help you better enjoy gazing at the night sky. If you ever feel uncomfortable or unsafe it is always better to play it safe and stargaze another night.
Make sure that you choose a place you feel comfortable and safe and if you can bring a friend along. An ideal place to view the night sky is far away from cities and a light pollution map can help you find a dark sky near you. Most of us live in or near cities and visiting a dark sky is not an everyday option. If you are observing from home or a nearby park avoid being in the line of sight of streetlights and turn off any indoor or outdoor lights that may be reaching your eyes.
Standing up and bending your head at the night sky is not comfortable to do for prolonged periods of time and a lawn chair or picnic blanket makes a huge difference. Avoid chairs with metal seating surfaces or add padding to keep yourself warm.
Bundle up! It gets cold at night even during summer. When stargazing you are unlikely to be moving around often and the cold temperatures will feel significantly colder than going on a walk.
If you live somewhere where bugs are a problem at night, wearing long sleeves and pants along with bug spray can be a huge help.
Be Comfortable and Prepared
Light Pollution Map of the San Francisco Bay Area
Wait for a clear calm moonless night. Depending on where you live clear nights may be very common or very rare. An area without excessive rain or heat can expect around 30 great clear nights a year. Thin wispy clouds or smoke in the upper atmosphere can be invisible to the naked eye but can make a clear night sky look washed out.
Observing the phases of the moon throughout the month can be a fun and rewarding experience but a near full moon washes out the stars in the sky. Waiting for a clear night around the new moon will help you see the most stars. My favorite way to check the moon phase is with this wall poster.
A regular weather app will work fine for forecasting observing conditions but an astronomy-specific weather forecast will provide more information. Astrospheric is a great free astronomy weather forecasting tool. With a free account, you can set up multiple observing locations as well as rise and set times for astronomical targets.
2. Wait for the Moon and Weather
3. Wait Until True Night
The stages of twilight from darkest (left) to brightest (right)
After sunset, the stars are not immediately visible with the glow of the Sun’s light illuminating the sky from beyond the horizon. Astronomically night is only when the Sun is 18 degrees or lower below the horizon. For far Northern and Southern latitudes there are days in the summer where the Sun will set below the horizon but never reach low enough for it to be truly night.
The time between sunset and sunrise and night is called twilight and is split into three distinct parts.
Starting right after sunset it is civil twilight while the Sun is between 0 and 6 degrees below the horizon. There is enough light to continue outdoor activities without any additional lighting.
Next is nautical twilight when the Sun is between 6 and 12 degrees below the horizon. At night it is hard to accurately locate the horizon. During nautical twilight, enough light remains to pick out the horizon against the ocean while simultaneously dark enough to see the brighter stars. This combination allows for accurate celestial navigation.
The last stage of twilight is astronomical twilight, with the Sun between 12 and 18 degrees below the horizon. In most cities and to most causal observers this is the darkest the sky will appear to get. However, the sky is not dark enough for viewing the dimmest stars and the dimmest deep sky objects. From light-polluted skies, the sky of astronomical twilight is no darker than night. However, from areas with dark skies, the difference between astronomical twilight and true night can be large, and twilight will appear to drag on much longer than from a city.
Finally, after astronomical twilight when the Sun is below 18 degrees, true night arrives. The opposite occurs during dawn with the Sun rising through astronomical twilight, then nautical twilight, then civil twilight, and continues until the break of day at sunrise.
4. Use a Star Chart or App
A good star chart will help you learn what’s up in the sky on any given night. There are many physical star charts such as planispheres or books on the night sky.
However, your smartphone can do a fantastic job of revealing what’s overhead. My personal favorite is Sky Guide but it is only available on iOS. Equivalents such as Sky Safari and Stellarium Mobile are available on Android and iOS. Stellarium (desktop version) is my favorite choice for computers. Both Sky Guide and Sky Safari provide lists of the best objects to on any given night. They also have augmented reality options that overlay their star chart over the sky using your phone’s camera.
While using one of these apps keep your screen brightness to a minimum or turn on their night view setting that turns the screen red. Using one of these apps can help you find your way around the night sky but a bright screen will remove your dark adaptation and prevent you from seeing all but the brightest objects in the sky.
Sky Guide - Phone View
Sky Guide - Tonight’s Best
5. Observe the Phases of the Moon
The moon is the brightest object one can see with the naked eye in the sky. The moon is actually visible during the day as well! My favorite way to keep track of the Moon’s phases is with this wall poster.
Viewing a crescent moon is best around the new moon and shortly after sunset or before sunrise. As the month goes on from the new moon you can watch the moon rise about an hour later every day as it grows to a half moon within a week. The moon will continue to grow in size for another week until full moon where it rises right after sunset. The moon will then begin to shrink over the next two weeks rising later in the night until rising and setting with the sun during the next new moon.
During the crescent moon phase look closely at the unilluminated part of the moon and you should barely be able to see it. Although the dark side of the moon is not illuminated by the sun, we can see it due to the light hitting the night side of the moon that has reflected off of the Earth.
The Crescent Moon with Earth Shine
6. Find and Track the Planets
The Motion of Mars from July 2005 - January 2006
Out of the 7 planets we can observe in the night sky (Earth not included), four of them are quite easy to find. If you see a bright star that does not twinkle it is likely a planet. The planets as progress in their orbits will appear to move in the sky against the background sky.
Venus sometimes called the evening or morning star, is the brightest planet in the sky and can be seen shortly after sunset and sunrise. It is a bright white point in the sky that can often be mistaken for a plane.
Jupiter is the next brightest planet and can be seen during most of the year when it is not close to the sun in the sky. It is a bright white point as well but not as bright as Venus.
Mars is a red point in the sky and drastically changes brightness as it moves closer and farther from us. It is a brilliant bright red when closest and a bit dim when far.
Saturn is a yellow point that is not bright but not dim. It has a very unique yellow shade unlike stars and is quite recognizable once you notice it.
Mercury is like Venus but is dimmer due to its smaller size and is often a challenge to observe as it is always very close to the Sun. Mercury is only easily observed a couple of days every 3 months when it reaches its greatest elongation (farthest angular distance from the Sun).
Uranus is barely visible to the naked eye in dark skies and Neptune requires binoculars or a telescope.
7. The Motion of the Sky
The sun and moon rise and set due to the rotation of the Earth. Just like the Sun and Moon, the stars move in the sky and do so for the same reason. Stars rise in the East and set in the West. To watch their motion go out and look at stars just above the horizon in the East. Come back an hour later and you will see those stars move higher into the sky.
The night sky throughout the year is not the same as the portion of the heavens visible at night changes throughout the year. As we move around the Sun the stars appear to rise and set earlier by about 4 minutes every day. To see this for yourself look East again and pick out a star just above the horizon or near a tree. Come back a few days later at the same time and the star will appear to be higher in the sky.
Taking images of the sky over a couple of hours lets us see the stars trail across the sky as the Earth rotates.
Star trails facing North
8. Naked Eye Deep Sky Objects
There are a couple of deep sky objects that you see with the naked eye even from a light-polluted sky. There are close to a hundred you can see with the unaided eye from a dark sky.
The two most notable are the Pleiades and the Orion Nebula. The Pleiades is an open star cluster visible during the fall and winter months and appears similar to a tiny big dipper in the sky. Referred to as the seven sisters there are 6-8 stars visible to the naked eye depending on your vision and how dark the sky is.
The Orion Nebula appears as a fuzzy star in the sword of the constellation of Orion. The nebula should be visible even in light polluted skies but more of the nebula is visible in darker skies.
Some other notable deep sky objects to see with the naked eye are the Hyades cluster that makes up the horns of Taurus, and the Beehive Cluster. Refer to a star chart for more.
The Pleiades, Hyades, and Orion
9. Find the Milky Way
The summer Milky Way stretching from Sagittarius on the right to Cygnus on the left
To have a chance at seeing the Milky Way you need to be in a sky that is Bortle 5 (dark suburban skies) or darker. Refer to this page by Astrobackyard for more on the Bortle Scale. Experienced observers can pick out the dust lanes faintly in brighter Bortle 6-7 (bright suburban skies).
The brightest part of the milky way is the core of the galaxy and is best seen from mid-Northern latitudes between May and August. The easiest way to spot the milky way is to look between the constellations of Sagittarius and Scorpius and a star chart app like Sky Guide can help you find them. The glow from the Milky Way can be seen extending from the horizon, a bit dimmer as it heads through Cygnus, and fading away as it passes to the North. Scanning the Milky Way with binoculars will let you see thousands of stars and a few star clusters and nebulae.
The Milky Way can be seen during the winter as well but it is the dimmer part of the galactic disk, facing out of the galaxy rather than towards the core.
10. Enjoy Meteor Showers
Meteor showers can be a fun and exciting experience. Under dark skies at the peaks of certain meteor showers, you can see up to 100 meteors per hour.
Meteor showers like any other type of night sky observing benefit greatly from being under darker skies. For the best meteor shower-watching experience plan to get away from city lights. Booking a campsite is a great way to get a safe place to observe a dark night sky. The best meteor showers of the year are often the Perseids in mid-August and the Geminids toward the end of November. Every year is different with some years having more or less meteors than others.
Avoid watching meteor showers close to the full moon. Sometimes the peak of a meteor shower can coincide with the full moon and watching a few days before and after will let you see more.
If you spend enough time under the stars you might be able to see a few meteors every clear night!
Geminids Meteor Shower
11. Find the ISS and More!
A train of Starlink Satellites (lower left) and a meteor (top right)
Our night skies are host not only to natural objects but man-made ones as well. There are tens of thousands of satellites in orbit right now with more being launched every month. An hour after sunset on a clear night you are to find at least a few small moving points of light in the sky.
The easiest to find is one of the largest and most famous, the International Space Station or ISS. You can this NASA Spot the Station page to find ISS sitings for your location. Most star chart apps will also have the ISS and Sky Guide provides notifications when an ISS pass is about to happen. You may have seen pictures of the ISS transiting the sun or the moon and can find transits here.
Shortly after a SpaceX Starlink launch you might also be able to see a train of Starlink satellites trail across the sky. They are most visible right after sunset and right before sunrise. See where Starlink satellites are right now here.