Yes, lava does emit light.
How Lava Emits Light
Objects that are very hot naturally emit electromagnetic radiation, and some of this radiation falls within the visible light spectrum, making the object appear to glow. This phenomenon is known as thermal radiation. The reference provided states, "Only very hot objects emit visible light (like an electric burner or the filament of an incandescent lightbulb)." Lava, being extremely hot molten rock, fits this description and therefore emits light.
Visible Light Emission
The type and wavelength of light emitted by a hot object depend on its temperature. For lava to be visible to the naked eye, it needs to be at a specific temperature threshold. According to the reference:
- Lava hotter than 900° C (1,700° F) glows red.
This means that when lava reaches or exceeds this high temperature, it becomes hot enough to emit light in the visible range, specifically appearing with a characteristic red glow.
Infrared Light Emission
As lava cools, its temperature drops. When it cools below the threshold for visible light emission, it stops glowing visibly. However, it doesn't stop emitting light entirely. The reference clarifies this:
- "As it cools, lava stops glowing visibly, but will continue to glow in lower energy wavelengths of near infrared and shortwave infrared light."
These types of infrared light are not visible to the human eye but can be detected with specialized equipment.
Temperature and Light Emission
Here's a summary of how lava's temperature relates to the light it emits, based on the provided information:
| Temperature | Type of Light Emitted | Visible to Human Eye? | Key Detail from Reference |
|---|---|---|---|
| Hotter than 900° C (1,700° F) | Visible Light (Red Glow) | Yes | "Lava hotter than 900° C (1,700° F) glows red" |
| As it cools (Below Visible) | Near Infrared & Shortwave Infrared Light | No | "As it cools, lava stops glowing visibly, but will continue to glow in lower energy wavelengths..." |
Key Takeaways
- Lava emits light because it is extremely hot, a process called thermal radiation.
- It emits visible light (specifically glowing red) when its temperature is above approximately 900° C (1,700° F).
- Even after it cools and is no longer visibly glowing, lava continues to emit infrared light.
