Hundreds of meteors streak through the sky every summer as part of the annual Perseid meteor shower. The Perseids, as they are known, are debris from the tail of Comet Swift-Tuttle. Earth passes through the comet's path, and tiny pieces of rocks and minerals from the tail enter Earth's upper atmosphere, burning up as "shooting stars."

Photograph by Steve Gifford, MyShot
  • The streak of light in this remarkable photograph is a "shooting star," a tiny speck of space debris burning up as it enters Earth's atmosphere.

    To the naked eye, a shooting star appears as a fleeting flash of white light. This image, however, documents the appearance of a wide spectrum of colors produced by the object as it hurdles toward Earth. These colors are predictable: first red, then white, and finally blue. If the meteor (shooting star) is large enough to survive the fall through the atmosphere, it cools and doesn't emit any visible light at all.

    The colors of this shooting star may also indicate the minerals that make up the space rock. Different elements emit different-colored light when they burn. Iron, one of the most common elements found in meteors, glows yellow. Silicates, which contain a form of the element silicon, glow red. A green glow, clearly visible in the trail of this shooting star, indicates the presence of burning copper.

    Understanding how, why, and when these colors appear is the science of spectroscopy.

    • Iron, which can give a meteor a yellow glow, is frequently used in fireworks to produce a gold color. Copper, which produces a tell-tale green or blue glow in meteors, isn't usually used for fireworks, however. Copper is unstable and difficult to manage at high temperatures.
    • Visible light is only a tiny part of the electromagnetic spectrum. A meteorite (or person!) at room temperature on Earth doesn't emit visible light, but they still "glow" in the infrared part of the spectrum. This infrared light is what heat-sensing cameras can display.
    • The Draper point is the temperature at which all solids begin to emit a dim, red glow. Below the Draper point, solid materials only "glow" in infrared. The Draper point is about 525 (977, or 798 Kelvin).
  • Term Part of Speech Definition Encyclopedic Entry
    atmosphere Noun

    layers of gases surrounding a planet or other celestial body.

    Encyclopedic Entry: atmosphere
    copper Noun

    chemical element with the symbol Cu.

    debris Noun

    remains of something broken or destroyed; waste, or garbage.

    Draper point Noun

    temperature at which almost all solid bodies at room temperature glow a dim red. The Draper point is about 525 Celsius (977 Fahrenheit, or 798 Kelvin).

    Earth Noun

    our planet, the third from the Sun. The Earth is the only place in the known universe that supports life.

    Encyclopedic Entry: Earth
    electromagnetic spectrum Noun

    continous band of all kinds of radiation (heat and light).

    element Noun

    chemical that cannot be separated into simpler substances.

    emit Verb

    to give off or send out.

    indicate Verb

    to display or show.

    infrared radiation Noun

    part of the electromagnetic spectrum with wavelengths longer than visible light but shorter than microwaves.

    iron Noun

    chemical element with the symbol Fe.

    meteor Noun

    rocky debris from space that enters Earth's atmosphere. Also called a shooting star or falling star.

    Encyclopedic Entry: meteor
    meteorite Noun

    type of rock that has crashed into Earth from outside the atmosphere.

    Encyclopedic Entry: meteorite
    mineral Noun

    inorganic material that has a characteristic chemical composition and specific crystal structure.

    rock Noun

    natural substance composed of solid mineral matter.

    shooting star Noun

    rocky debris from space that enters Earth's atmosphere. Also called a meteor.

    silicate Noun

    most common group of minerals, all of which include the elements silicon (Si) and oxygen (O).

    silicon Noun

    chemical element with the symbol Si.

    spectroscopy Noun

    science of the measurement of light that is reflected, absorbed, or emitted by different materials.

    spectrum Verb

    continuous band of material with each piece differing in small amounts from the piece before and after it.

    temperature Noun

    degree of hotness or coldness measured by a thermometer with a numerical scale.

    Encyclopedic Entry: temperature
    visible light spectrum Noun

    light and colors that can be seen by human beings.