And mathematically, you can express that in terms of how much that object subtends.

从数学 上讲，您可以用该对象对向的程度来表达这一点。

The supermassive black hole is 27,000 light years away and subtends an angle of just 52 microarcseconds in the sky.

这颗超大质量黑洞距离我们27000光年，它在天空中仅52微角秒的角度。

An object is said to subtend a certain angle of your vision based on how close you are to it, and how big it is.

根您 与它的接近程度以及它的大小，说一个物体对着您的视野的某个角度。

So if you look at our tiny leaf, it may subtend only two degrees of your vision when it’s at your near point – say, 25 centimeters away.

所以如果你看我们的小小叶子，当它在你的近点位置时——比如，25厘米远处——它可你视野中的两度视角。

But when you look at the leaf through the lens, the virtual image is larger than the actual object, so it subtends six degrees of your vision.

但是当你通过镜头看树叶时 ，虚像比实际物体大， 所以它对着你的视线六度。

So if you look at our tiny leaf, it may subtend only two degrees of your vision when it's at your near point – say, 25 centimeters away. .

因此，如果您看我们的小叶子， 当它在您的近点（例如 25 厘米远）时，它可对着您的视线的两度。

In order to find the magnifying power of the lens, you just divide the angle subtended by the virtual image by the angle subtended by your unaided eye.

为了求出镜片的放大倍率 ，需用虚 像对角除以肉眼对角。

He noted that it subtended, or spanned, an angle of 76 arcseconds, 76 three thousand six hundredths of a degree, at Earth, which was smaller than the value guessed by Kepler.

他注意到金星在地球上所张的角度，即跨度， 为76角秒， 即76/3600度，这个数值比开普勒所猜测的要小。

And the newly subtended angle is the amount that the object subtends when viewed through the eyepiece – the angle between your eye and the rays from the eyepiece.

而新的张角是物体通过目镜观察时所张开的角度——即你的眼睛与目镜发出的光线之间的角度。

For example, if you’re looking up at the moon, and you cover it with your thumb, then your thumb and the moon are both subtending the same angle to your eye, which we measure in degrees.

例如，当你抬头看月亮时，如果用拇指遮住它，那么你的拇指和月亮在你眼中所张开的角度是相同的，我们用度数来测量这个角度。

For example, if you're looking up at the moon, and you cover it with your thumb, then your thumb and the moon are both subtending the same angle to your eye, which we measure in degrees.

例如，如果你抬头看着月亮，然后用拇指遮住它，那么你的拇指和月亮都对着你的眼睛，我们用度数来衡量这个角度。