No, planets generally do not blink, or twinkle, in the sky as stars do.
Why Planets Don't Twinkle Like Stars
The primary reason behind this difference lies in their distance from us:
- Stars are incredibly far away: Because stars are so distant, their light reaches us as very narrow beams.
- Planets are much closer: Planets, being significantly nearer, appear as disks rather than pinpoint sources of light.
How Atmospheric Turbulence Affects Light
Our atmosphere is not perfectly still; it's filled with pockets of air at slightly different temperatures. This causes the light from celestial objects to be refracted (bent) as it passes through.
- Stars Twinkle: The narrow beam of light from a star is easily affected by this atmospheric turbulence, causing the apparent position and brightness of the star to fluctuate rapidly – hence, the twinkling effect.
- Planets Don't Twinkle Much: The light from a planet, which is spread across a small disk, is less affected by the turbulence. Some light rays may be bent one way, while others are bent in different ways, averaging out the effect so the planet appears more stable and less blinky. The reference states that "Planets don't appear to twinkle much at all" because the beams of light from closer planets are less affected by the atmosphere than those from distant stars.
- Closer Proximity: As our reference notes: "Stars are MUCH farther away from us than planets, so the beam of light from a star is affected more by passing through our atmosphere than the beam of light from a much closer planet."
- Atmospheric Cause: It is the movement and variation in our air that causes the twinkling.
Exceptions
While planets generally don't twinkle, you might notice a slight shimmering, particularly when they are low on the horizon. This is because the light is passing through more of the atmosphere, increasing the chance of turbulence.
Summary
| Feature | Stars | Planets |
|---|---|---|
| Distance | Extremely far away | Relatively close |
| Light Source | Point source of light | Disk-like source of light |
| Twinkling | Significant twinkling | Very little to no twinkling |
| Cause of Twinkle | Affected by atmospheric turbulence | Less affected by atmospheric turbulence |
