Download This Sample
This sample is exclusively for KidsKonnect members!
To download this worksheet, click the button below to signup for free (it only takes a minute) and you'll be brought right back to this page to start the download!
Sign Me Up
Table of Contents
Comets are ice comets composed of frozen gases, minerals, and dirt that remain after the solar system’s formation. They travel in eccentric orbits around the sun, which may span hundreds of thousands of years. As a comet reaches the sun, it rapidly warms up, forcing solid ice to sublimate straight into a gas. The gas, which comprises water vapor, carbon monoxide, carbon dioxide, and other significant elements, is finally swept into the comet’s characteristic tail. According to NASA, comets are frequently referred to as “dirty snowballs” or “snowy dirtballs,” depending on whether they carry more ice or rocky debris.
See the fact file below for more information on comets, or download our comprehensive worksheet pack to utilize within the classroom or home environment.
Facts & Information
Dirty Snowballs: Comets
- Comets are dirty snowballs comprised primarily of ice and frozen carbon dioxide, with tiny dust and organic molecules held over from the solar system’s birth.
- They serve as “time capsules,” indicating what conditions were once in our solar system when the sun and planets originally formed 4.5 billion years ago.
- Comets form in the cold reaches of our solar system, and one will occasionally make its way towards the sun. As the sun nears, the comet heats up, and the ice, carbon dioxide, and debris trapped inside evaporate, bursting out in dazzling jets.
Physical Characteristics
- A comet’s main components include its nucleus, coma, hydrogen envelope, dust, and plasma tails. Scientists analyze these components to discover the size and position of the frozen bodies.
Nucleus
- The nucleus is the solid interior structure of a comet. Rock, dust, water, ice, frozen carbon dioxide, carbon monoxide, methane, and ammonia make up the cometary nucleus.
- After Fred Whipple’s model, they are called “dirty snowballs.”
- Comets with a more excellent dust content have been dubbed “icy dirtballs” following the observation of Comet 9P/Tempel 1 colliding with an “impactor” probe delivered by NASA’s Deep Impact mission in July 2005.
- The exterior of the nucleus is often dry, dusty, or rocky, implying that the ices are concealed behind a several-meter-thick surface crust.
- In addition to the previously stated gases, the nuclei include a variety of organic chemicals such as methanol, hydrogen cyanide, formaldehyde, ethanol, ethane, and maybe more complicated molecules such as long-chain hydrocarbons and amino acids.
- Cometary nuclei’s exterior surfaces have an extremely low albedo, placing them among the least reflecting objects in the Solar System.
Coma
- Streams of debris and gas are discharged from the “coma,” a vast and fragile atmosphere surrounding the comet.
- The coma is strained by the sun’s radiation force and solar wind, creating a gigantic “tail” that moves away from the sun.
- The coma is typically composed of water and dust, with water accounting for up to 90% of the volatiles that escapes from the nuclei when the comet is 3 to 4 astronomical units from the sun.
- Although the solid core of a comet is typically less than 60 kilometers (37 mi) in diameter, the coma may be hundreds or millions of kilometers in diameter, perhaps exceeding the size of the sun.
- The sun illuminates the coma and the tail, which may be observed when a comet travels within the inner solar system.
Bow Shock
- The collision of the solar wind and the cometary ionosphere, created by the ionization of gases in the coma, causes bow shocks.
- The coma extends as the comet reaches the sun due to higher outgassing rates, and sunlight ionizes gases in the coma. The bow shock occurs when the solar wind passes through this ion coma.
Tails
- Comets in the outer solar system stay frozen and inactive, making detection from Earth difficult or impossible.
- Hubble Space Telescope studies have recorded statistical detections of dormant comet nuclei in the Kuiper belt. However, these detections have been called into doubt.
- As a comet reaches the inner solar system, solar radiation drives the comet’s volatile elements to evaporate and stream out of the nucleus, dragging dust with them.
- Each dust and gas stream has a distinct tail that points in somewhat different directions. The dust tail is left behind in the comet’s orbit, so it frequently forms a curved tail known as the type II or dust tail.
- At the same time, the type I tail, which is formed of gases, typically heads away directly from the sun because this gas is more severely impacted by the solar wind than dust and follows magnetic field lines rather than orbital paths.
Jets
- Uneven heating can allow freshly created gases, like a geyser, to erupt out of a weak area on the surface of a comet’s nucleus.
- These gas and dust streams can lead the nucleus to rotate and perhaps split apart.
- Showed dry ice (frozen carbon dioxide) capable of powering comet nucleus jets in 2010. Infrared imaging of Hartley 2 reveals the presence of such jets, which transport dust grains into the coma.
Comets Size
- Comets are pretty tiny in comparison to planets. Their average diameters typically range between 750 meters (2,460 feet) to 20 kilometers.
- Infrared light is critical for determining the size of a comet. We notice the light that a comet radiates from the sun when we see it in visible light.
- As a result, a massive, black comet may seem identical in size to a small, significantly reflecting comet. In infrared light, however, the brightness of a comet is determined by the amount of heat it collects from the sun and re-radiates back towards space.
- Because a vast comet has a greater surface area, it generates more heat and looks warmer when near-infrared. A comet’s nucleus can range in size from a couple of hundred meters to tens of kilometers, yet its tails can be millions of kilometers long.
Orbital Characteristics
- Most comets are small solar system entities with long elliptical trajectories that carry them near the sun for part of their orbit and then away into the solar system for the rest.
- Comets are frequently classed based on the duration of their orbital periods, and the ellipse becomes longer as the period increases.
Short Period Comets
- Periodic comets, sometimes short-period comets, have orbital periods of fewer than 200 years.
- They usually circle in a similar direction as the planets, roughly on the ecliptic plane. Their orbits often carry comets to the zone of the outer planets (Jupiter and beyond) and aphelion; for example, Halley’s Comet’s aphelion is a little beyond Neptune’s orbit.
- Comets with aphelia near a giant planet’s orbit are called a “family.” Such families are theorized to emerge due to the planet trapping formerly long-period comets into shorter rotations.
- Comets discovered recently in the central belt comprise a unique class, circling in relatively circular orbits within the asteroid belt. Comets are exposed to additional gravitational disturbances since their elliptical orbits often bring them near to the more giant planets.
- Short-period comets are supposed to originate from centaurs, and the Kuiper belt/scattered disc – a disk of objects in the trans-Neptunian region – but long-period comets are believed to originate from the considerably more distant spherical Oort cloud.
Long Period Comets
- Long-period comets have very eccentric orbits with durations that range from 200 to hundreds, if not millions, of years.
- A comet with an eccentricity more prominent than one around perihelion does not always escape the solar system.
- When the osculating orbit is calculated at an epoch after departing the planetary zone and concerning the solar system’s center of mass, the prospective orbit of a long-period comet is correctly derived.
- Long-period comets, by definition, stay gravitationally tied to the sun; comets expelled from the solar system due to comparative approaches by giant planets are no longer regarded as “periods.”
- Long-period comets’ orbits send them well outside the outer planets at aphelia, and the plane of their orbits must be close to the ecliptic.
Oort Cloud and Hills Cloud
- The Oort cloud is estimated to cover a large area ranging from 2,000 to 5,000 AU (0.03 to 0.08 light years) to 50,000 AU (0.79 light years) towards the sun.
- This cloud encases the celestial bodies that begin in the center of our solar system – the sun – and extend to the Kuiper Belt.
- The Oort cloud is made up of viable ingredients required for the formation of celestial bodies.
- The Oort Cloud exists because of the eccentric created by these imprisoned planetesimals. According to some estimations, the outside margin is approximately 100,000 and 200,000 AU.
- The area is separated into two parts: a spherical outer Oort cloud of 20,000-50,000 AU (0.32 – 0.79 light years) and a doughnut-shaped inner cloud, the Hills cloud, 2,000-20,000 AU (0.32 – 0.79 light years).
Exocomets
- Exocomets discovered outside the solar system may be prevalent in a milky fashion.
- In 1987, they discovered the first exocomet system near Beta Pictoris, a relatively young A-type main-sequence star.
- As of 2013, 11 such exocomet systems have been detected utilizing the absorption spectra induced by enormous clouds of gas released by comets when they pass near their star.
Fate of Comets
- Departure from the solar system: A comet may escape the solar system if it travels fast enough. Such comets are known as hyperbolic comets because they follow the open path of a hyperbola.
- Solar comets are mainly known to be expelled by colliding with other solar system objects, such as Jupiter.
- Exhaustion of volatiles: Jupiter-family comets and long-period comets tend to have distinct fading rules. JFCs last 10,000 years or 1,000 orbits, whereas long-period comets diminish considerably faster.
- Just 10% of long-period comets withstand more than 50 perihelion crossings, and only 1% survive more than 2,000 trips.
- Most of the volatile material in a comet’s nucleus eventually evaporates, and the comet becomes a tiny, black, inactive lump of rock or debris that resembles asteroids.
- Breakup and collisions: The nucleus of certain comets may be fragile, as evidenced by observations of comets breaking apart.
- Some comets have a more dramatic finale, collapsing into the sun or colliding with a planet or other matter. In the early solar system, comets and planets or moons clashed often.
Comets Worksheets
This bundle contains 11 ready-to-use comets worksheets that are perfect for students who want to learn more about comet which are a ball of mostly ice that moves around in outer space.
Download includes the following worksheets:
- Comet Facts
- What Makes a Comet?
- Parts of a Comet
- Matching Type
- Fact or Bluff
- Know Meteors
- Meteor Shower
- Word Search
- Compare and Contrast
- Collision Course
- Word Jumble
Frequently Asked Questions
What are comets called?
Comets are dirty snowballs comprised primarily of ice and frozen carbon dioxide, with tiny dust and organic molecules held over from the solar system’s birth.
How are comets formed?
Comets form in the cold reaches of our solar system, and one will occasionally make its way towards the sun. As the sun nears, the comet heats up, and the ice, carbon dioxide, and debris trapped inside evaporate, bursting out in dazzling jets.
How giant is a comet?
Comets are pretty tiny in comparison to planets. Their average diameters typically range between 750 meters (2,460 feet) to 20 kilometers.
What are two types of orbital characteristics of a comet?
Comets have two types of orbital characteristics short-period comets have orbital periods of fewer than 200 years, and long-period comets have very eccentric orbits with durations that range from 200 to hundreds, if not millions, of years.
How does a comet end?
Some comets have a more dramatic finale, collapsing into the sun or colliding with a planet or other matter. In the early solar system, comets and planets or moons clashed often.
Link/cite this page
If you reference any of the content on this page on your own website, please use the code below to cite this page as the original source.
Link will appear as Comet Facts & Worksheets: https://kidskonnect.com - KidsKonnect, September 23, 2017
Use With Any Curriculum
These worksheets have been specifically designed for use with any international curriculum. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards.