How do I see the ISS from Earth? 

The International Space Station (ISS) is so large that it’s visible from Earth without a telescope!  The International Space Station is approximately 250 miles above the surface of the Earth in Low Earth Orbit. Traveling at approximately 17,500 miles per hour, the ISS circles the globe once every ninety minutes. 

Photo Credit: NASA

Why is the ISS moving across the sky? 

The ISS resides in Low Earth Orbit (LEO). Objects in LEO circle the globe. Objects in Geostationary Orbit (GEO) do not circle the globe and remain stationary above one location.

  • Satellites in Low Earth Orbit travel at approximately  4.85 miles per second (7.8 km per second) with an altitude of approximately 160 km to 1000 km above the earth. LEO satellites circle the globe sixteen times each day. The ISS is in LEO.
  • Satellites in Geostationary orbit travel approximately 2.26 miles per second (3.8 km per second) with an altitude of approximately 36,000 km above the earth. GEO satellites match the Earth’s rotation speed, appearing “stationary” above the Earth. 
Photo Credit: NASA

Where do I look? 

The ISS is in a constant state of motion. Atmospheric drag and Earth’s gravity create orbital altitude degradation on the ISS. Changes in the ISS’s altitude modify its trajectory. In theory, the exact orbit path will repeat every three days. 

A good way to determine when the ISS will be traveling near you is to use NASA Spot the Station website. Entry your city, and the website generates a list of upcoming passes near your location. Don’t worry if your exact city isn’t listed. Pick a city that’s close to you. 

DateVisibleMax Height*AppearsDisappears
Today, 5:30 AM5 min23°10° above S10° above ENE
Today, 4:44 PM2 min11°10° above SE10° above ESE
Tomorrow, 6:18 AM6 min29°10° above WSW10° above NNE

Here’s an example of a flyby chart from the NASA Spot the Station website based on your current location. 

International Space Station
Photo Credit: European Space Agency

Which direction should I look?

Take a few moments to orient yourself outdoors. Which direction is N, S, E, W?  

Old School: 

  1. Use a compass and orient yourself in the proper direction
  2. Use your hands to determine approximate viewing height
    1. Make a fist, knuckles rolled forward, and raise it to eye height
    2. The approximate distance from your thumb to your pinky finger is 10°
    3. Make the “hang loose” or “aloha” symbol with your hand. It’s 25° from your pinky to your thumb.
    4. Pay close attention to the ISS Max Height above the horizon. Landscapes or buildings can easily (easily) cover up to 15-20° of the horizon. 

New School: 

  1. Use your favorite cell phone app to orient yourself (N,S,E,W) 
  2. Use the app to find the ISS
  3. (-) cell phone brightness
Diagram Credit: NASA

There it is!

Now that you’re oriented and know where to look, it’s time to locate the ISS!  Be patient and relax.  Soon enough, you’ll see satellites, even if they’re not the ISS.

What’s a Starlink Satellite Train?

When viewing conditions are “correct,” it’s possible to see a string of satellites traversing the nighttime sky lined up in a row.   This unusual sight is known as a Satellite Train.

starlink satellite train
Photo Credit: Forest Katsch

The number of Low Earth Orbit (LEO) satellites launched is growing each year. The increased number of satellites in orbit has a direct impact on how we view our nighttime skies. Starlink has approximately 3,800 satellites circling the Earth.

Where are the satellites now?

Heavens-Above and Constellation Starlink have fantastic interactive 3D models. The sheer volume of Starlink Satellites is stunning. Select Live Map and locate the satellite train that’s closest to you on Findstarlink

Geostationary and Low Earth Orbiting Satellites

  • Geostationary (GEO) Satellites are 36,000 km above the Earth.
    • Slow upload/download times.  (High latency.)
  • LEO satellites are approximately 160 km to 1000 km above the Earth.
    • Fast upload/download times. (Low latency.)
view from a satellite
Photo Credit: NASA

What’s a Starlink Satellite?

A Starlink Satellite transmits internet signals from a satellite to a ground transceiver. The ground transceiver sends a signal to a router. The end user connects to the internet through the router. 

LEO satellites are constantly “on the move” as they circle the Earth.  This includes crossing over the oceans that cover 71% of the globe.

The best way to ensure global coverage is to place additional satellites into orbit. Each Starlink launch adds approximately 50-60 Starlink Satellites. Starlink is planning on weekly launches.

Who needs it?

Starlink plans to provide high-speed internet access to communities with poor internet service.  Poor service may be due to geographic location or lack of infrastructure.

space capsule
Photo Credit: Jeremy Straub

How Many?

Starlink is the first company to place satellites, in bulk (3,271), into LEO. Starlink currently has FCC approval for 12,000 satellites. Starlink’s projected build-out is closer to 42,000 satellites. A baseline expectation is 100,000 satellites in LEO, (all companies/nations combined) by 2030.

What’s a Starlink Satellite train?

Starlink satellites begin orbit at the approximate height of 350 km and move to an altitude of 550 km. They travel “in a row” as they orbit the Earth. The satellites are visible to the naked eye when they’re at a lower elevation.

A Starlink Satellite train is a row of Satellites traveling across the sky “in a row” or a “string of pearls.”

Astronomers express concern

Astronomers worry that the satellite trains will impact scientific research.  Papers are being published highlighting the satellite train’s negative impact on astronomy.

Astronomers are reflecting on the Kessler syndrome as a real possibility: A satellite breaks or shatters into smaller pieces. A second satellite files through the debris field. The second satellite breaks or shatters into smaller pieces.  Snowball effect.

starlink satellite
Photo Credit: Marek Piwnicki

Moving forward

Faster internet connections may be the beginning of an economic equalizer for less developed regions. Increasing the number of satellites in low earth orbit may cause considerable scientific angst. What’s the right answer?  

Galaxies- A Look Into the Stars

The science of astronomy has defined a galaxy as a system of stars, planets, dust, and other materials that revolve around a common center of mass. A galaxy can be very large and include billions of stars.

Photo Credit: Bryan Goff

Many galaxies have names. The names are often based on the constellation or the location of the star. Some galaxies have more interesting names than others. Most of these are named by astronomers who discovered them.

Spiral Galaxies

Spiral galaxies are the brightest galaxies that are far away. They are made up of stars and planets that are rotating in the opposite direction to shape the galaxy. There are lots of colors in the material in these galaxies. Another type of galaxy is an elliptical galaxy. These galaxies are shaped like grains of rice.

Galaxies are grouped together based on their gravitational attraction. Many galaxies are also grouped into clusters. One of these groups is the Local Group of 54 galaxies. This group includes our own Milky Way galaxy. It consists of hundreds of billions of stars.

spiral galaxy
Photo Credit: NASA

Types of Galaxies

Most modern catalogs of galaxies contain thousands of objects. The New General Catalog of Principal Galaxies, for example, has over 73,000 objects in it. When a new catalog is published, most of the objects have catalog designations. For instance, the Whirlpool Galaxy is a Messier object. Another example is the Pinwheel Galaxy, which is located in the Coma Benerices constellation.

Galaxies can be classified into three basic types. These are barred spiral, barred elliptical, and elliptical. While most are categorized by their size, some are still grouped by their shape. In general, a galaxy is a collection of planets and stars, but can also be a system of nebulae and dust.

The names of galaxies can vary, depending on how the catalog is compiled. Some galaxies are not included because they do not show up as separate objects in the sky. Others are only part of larger galaxy clusters. An example is the Sagittarius Dwarf Spheroidal Galaxy, which is not listed because it is not seen as a separate galaxy.

There are also a number of unusually shaped galaxies. These include galaxies in the process of colliding, and galaxies with active nuclei. These objects are thought to be in a transitory phase of galactic development.

Photo Credit: Greg Rakozy

Where Do Galaxies Get Their Names?

Several ancient cultures named ten thousand stars. However, there are only a few thousand that are bright enough for human observation with the naked eye. Using the names of stars and constellations is a great way to learn about outer space and the universe. You can also visit a planetarium to see displays of deep-space features.

Although it can be challenging to identify certain galaxies, the International Astronomical Union has produced several official catalogs. The New General Catalog of Nebulae and Star Clusters is the most widely used catalog. Other popular catalogs are the Atlas of Peculiar Galaxies, the Extragalactic Catalog, and the Markarian Catalog.

What is the Coldest Place in the Universe?

We know that Uranus is the coldest planet in the Solar System, existing at a frigid minus 371 degrees Fahrenheit. Have you ever wondered what the coldest place in the universe is?

coldest place in the universe
Photo Credit: Tasos Mansour

It’s well-known that there is a lower temperature limit: absolute zero. At absolute zero (minus 459 degrees Fahrenheit), all of the atomic and subatomic particles stop moving. Temperature measures the kinetic energy of matter. Namely, temperature describes how fast the atomic and subatomic particles in matter are moving. The faster they move, the higher the temperature. When they completely stop moving, they have zero kinetic energy and have reached absolute zero.

If there is no matter, there is no temperature. Thus, a complete vacuum has no temperature. It is neither cold nor hot. Deep space is not a complete vacuum; it has a tiny amount of matter in it that was created and heated by the Big Bang. Space has a temperature of minus 455 degrees Fahrenheit, which is clearly above absolute zero.

Photo Credit: NASA

Boomerang Nebula: The Coldest Place in the Universe

The coldest place in the universe that anyone has observed so far is the Boomerang Nebula, which is about 5000 light years away from the Earth. Part of the Boomerang Nebula is estimated to be a frigid minus 457 degrees Fahrenheit, actually cooler than deep space and barely above absolute zero. The Boomerang Nebula is believed to be a dying star system. The star is spraying solar winds carrying mass and starlight out into space, where it rapidly expands and the particles push against the particles present in deep space, transferring some of their kinetic energy and causing the area around the dying star to cool below the background temperature of deep space.

Photo Credit: NASA

Thus, while Uranus may be the coldest planet in the Solar System, it is not the coldest place in the universe and it’s a lot warmer than deep space and significantly warmer than the Boomerang Nebula.

How do Scientists Measure the Temperature of Planets?

temperature of planets
Photo Credit: Matteo Fusco

When determining what the coldest planet is, we must first ask how the temperature of planets are measured. Knowledgable people immediately answer “Uranus of course; the temperature on Uranus is minus 371 degrees Fahrenheit”. How does anyone know that? Did we shoot thermometers at the planet or something?

Actually, scientists HAVE placed thermometers on some planets, most notably Mars. But for the more distant planets like Uranus, scientists estimate the temperature by looking at the light emitted by the planet. When estimating temperature, scientists don’t look at visible light; they look at infrared light, the light that has a longer wavelength than the red light that we can see.

red hot coals
Photo Credit: Michal Matlon

Planck’s law is a formula that calculates how much light is emitted at each wavelength from an object based on its temperature. This law is firmly founded on the basics of quantum mechanics, thermodynamics, and relativity. You can obtain an intuitive understanding of what the scientists are doing by looking at the coals of a fire. The hotter coals emit a lot of white light, less-hot coals glow red, and cool coals do not emit any visible light.

What Tools Are used to Calculate the Temperature of Planets?

Scientists use a device called a bolometer to convert the infrared light the planet emits at different wavelengths into distinct electrical signals, which can be converted into an estimate of the temperature of the planet. Similar technology is currently in use in thermal imagers and cameras, which are inexpensive and widely available. These devices are used for all sorts of purposes, such as checking for insulation leaks, determining if an infant has a fever, and observing wildlife in the dark.

Photo Credit: ActionVance

It’s rather astonishing that you can buy a thermal imager at Walmart for under $100 that works on the same principles that scientists use to estimate the temperatures of objects that are billions of miles away.

How Old is The Sun?

sun and clouds
Photo Credit: Pixabay

The Sun has been providing the Earth with sunlight for several billion years. Have you ever stopped and actually asked yourself How Old is the Sun? At some point, both celestial bodies will die, but while the Earth is expected to become uninhabitable within the next billion years, the Sun has a much longer lifespan.

The Sun is estimated to be 4.6 billion years old, making it one of the oldest entities in the Solar System. Despite the star’s age seeming like a massive number, the Sun is at the middle point of its life. Here’s a quick look at the Sun’s life cycle, from its formation to its ultimate demise.

What Is the Life Cycle of the Sun?

The Sun’s lifespan can be narrowed down to three phases: its formation, current state, and death.

The Formation

Simply put, the Sun was initially part of a hydrogen and helium molecular cloud before a nearby supernova’s shockwave forced it to become a star. In reality, that shockwave caused the cloud’s molecules to compress. Along with a rotating motion, a part of the cloud built up much heat and pressure in its core, leading to the formation of a star with disks surrounding it. 

That’s how the Sun (star) and the planets (disks) of the Solar System were formed.

NASA sun photo
Photo Credit: NASA

The Main Sequence

The Sun is almost at the midpoint of its main sequence phase, during which nuclear fusion occurs, turning hydrogen into helium. As the millennia pass, the star will continue depleting its core’s hydrogen while it also grows in size and emits an increasing amount of solar radiation.

The Sun’s main sequence phase is estimated to last 9-10 billion years. Considering it’s already 4.6 billion years old, it should have enough hydrogen in its core for almost 5 more billion years.

After Hydrogen Exhaustion

Once all the core’s hydrogen is exhausted, the Sun will spend a billion years expanding until it becomes a Red Giant. At that point, about 6 billion years away, the Sun’s surface will be close to Mars, and its luminosity will be 1000 times stronger. 

The Sun will spend around a billion years as a Red Giant before depleting its core’s helium, leading to an unstable phase and the beginning of its death.

How Old is The Sun and When Will The Sun Die?

The Sun’s death begins with an explosion (planetary nebula), followed by the star becoming a White Dwarf. From then on, estimates have shown that the Sun’s White Dwarf phase will last for billions, if not trillions of years, before turning into a Black Dwarf, at which point it won’t emit any light or heat.

How old is the sun
Rendering Credit: Pixabay


Even though the Sun is 4.6 billion years old, its core contains enough hydrogen to keep the star stable for another 5-6 billion years. Once the hydrogen is depleted, the Sun will gradually get larger before becoming a Red Giant. 

A billion years after the beginning of the Red Giant phase, the Sun will unstably increase in size before exploding into a planetary nebula and becoming a White Dwarf. At that stage, the Sun will be dead. However, it will still emit light and heat for billions or trillions of years before it turns into a Black Dwarf.

If you want to get a better idea of how we know how old the Sun is and what will happen to the Solar System, feel free to go through our in-depth analysis of the Sun’s and Solar System’s lifetime.