Could it be a typo for "and one by one they will be turned off"? CNN:

Many of the existing space telescopes, Hubble included, are nearing the end of their lifetimes, and one by one they will turn off. Without the James Webb Space Telescope, our eyes on the universe would be closed for the foreseeable future.

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    – Tom Au
    Commented Aug 30, 2011 at 19:56

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There is no mistake here.

Turn off is active. When transitively used ("subject turns object off"), the subject is turning off the object. When intransitively used ("subject turns off"), the subject turns itself off.

Be turned off is passive, indicating that the subject is not doing anything to turn itself off, and implying that some other force is acting on it to turn it off.

In this case, the active form was presumably used because the telescopes will (actively) use up their power (causing themselves to turn off) rather than someone flipping a switch somewhere to turn them off. So since it will be the telescopes' power drainage or mechanical failure that turns them off, the telescopes are described as turning themselves off.


This isn't a typo--the two phrasal verbs are slightly different. If the telescopes turn off, then they are doing it themselves. If they are turned off then it means that some external force (perhaps a NASA kill switch) is turning them off.


The telescope is like a light bulb that can BE turned on and off by a person throwing a light switch.

But if a light bulb is turned on and then left to itself, it will eventually turn ITSELF off--when it burns out. Telescopes have a similar property.


The majority of the time, turn off with this meaning is a transitive verb. I'd say, I turned off the stove, but I'd be less likely to say the stove turned off; I'd only say the latter if it was clear from context that something happened to the stove to make it turn itself off.

Power down and switch off are similar. Shut down is similar as well, but we're probably more familiar with seeing this used intransitively because we often think of computers or software as doing things for themselves. In your example, the telescopes turn themselves off, because they are at the end of their lives. We can infer that they will run out of power, or they will receive a signal to turn off, much as we say a computer shuts down.

Some examples of intransitive use from COCA:

" My father says that the lights will turn off like that every night. " " That can't be right, " said Mircea. " Last night it was just some technical problem. "

Most evenings after dinner I hear his radio switch off, then his door open and shut...

The armor would power down, of course, once I removed it.


Could this be a typo? As drm65 noted, "turn off" is active, and "be turned off" is passive, but I believe your problem isn't with that, but rather that you are wondering, "How can these telescopes turn off by themselves? Is this a typo?"

If so, good point, because the telescopes generally don't get turned off by themselves, as they are turned off by human means. We usually state:

James turned off the fan.
Sarah turned off the car.

We don't state:

The car turned off.
The fan turned off.

So, I believe you have a good point there. Unless the telescopes are going to turn off automatically by themselves (and I don't think so), this would probably be a slip of the pen.


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