Name: 衛星星座對天文學有多壞？| 衛星星座對天文學有多壞？ (How Bad Are Satellite Constellations for Astronomy? | SciShow News)
Uploaded: 2021-01-14T10:28:23.000Z
Duration: 4 min 58 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

on one of the world's most advanced telescopes,

careful to put in all the right parameters,

But later, when you review the data, you're devastated.

Bright spots and streaks of light ruined tons of your photos.

and a scenario a lot of people are worried will become

here could be more than 26,000 new satellites orbiting Earth,

compared to the 5500 or so up there right now.

So the European Southern Observatory, or ESO,

decided to figure out what this means for astronomers.

in the journal Astronomy and Astrophysics,

they looked at the possible impact of these new satellites

they won't interfere as much as you might expect.

But for some research, they could be a big problem.

The surge of satellites comes from an idea multiple companies are pursuing:

Satellite-based internet has been around since the '90s.

But the satellites used for it are so high above Earth

that it takes more than half a second for a signal

to get from you to somewhere else and back.

but think about how annoying a half-second lag is during a video call.

These new satellites are designed for a much lower orbit,

though, bringing the delay down to around a 30th or 40th of a second.

That's similar to what you might get on a decent regular broadband connection.

And for people in remote or underserved areas,

that type of internet access could be a game-changer —

So there are advantages to these satellites.

But astronomers have been worried about the downsides.

if they absorbed most of the sunlight that hit them, they'd overheat fast.

They also move across the sky much faster than, say, a star.

So if you're taking a long-exposure photo,

where the shutter stays open for a while,

you could end up with a bright streak against the background of stars.

Even worse, if the streak is bright enough,

the light could overwhelm the sensors and ruin the photo entirely.

But the new ESO study shows that in many cases,

Generally, you can only see satellites overhead during astronomical twilight,

when the Sun is 12 to 18 degrees below the horizon,

and for an hour or so at the start and end of the night.

For the rest of the night, most satellites are in Earth's shadow.

So the issue is only within a certain timeframe.

And even then, for many types of observations,

the satellites would only cause problems for a small fraction of data.

Based on how the satellites would be distributed and how visible they'd be,

the researchers concluded that for short and medium exposures —

At most, about 0.5% of observations could be ruined,

if you're only looking at a narrow field of the sky,

The team estimates that around 1 to 5% of exposures

would be ruined at the start and end of the night,

And if you have a really big telescope looking at a very wide section of the sky?

For example, at the Vera C. Rubin Observatory,

a powerful wide-field telescope that's under construction in Chile,

around a third of the exposures would be ruined

during the beginning and end of the night,

The only time that would be unaffected is the middle of winter.

Thankfully, the team did have suggestions

not collect data during part of the night.

Or, if you know where the satellites are,

for a time when your part of the sky will be satellite-free.

So another option would be to keep track of where the satellites are at any given time,

if you know a satellite will cross the telescope's field of view,

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衛星星座對天文學有多壞？| 衛星星座對天文學有多壞？ (How Bad Are Satellite Constellations for Astronomy? | SciShow News)

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