A needle in countless haystacks: Finding habitable worlds - Ariel Anbar

Translator: tom carter Reviewer: Bedirhan Cinar

Translator: Tom Carter Reviewer: Hafizh Alfarisi

The universe contains about 100 billion galaxies.

Alam semesta berisi 100 miliaran galaksi.

Tiap galaksi berisi 100 miliaran bintang.

Each of those galaxies contains about 100 billion stars.

Kebanyakan bintang diputari planet-planet.

Many of those stars have planets orbiting them.

So how do we look for life in all that immensity?

Bagaimana menemukan kehidupan di tengah keluasan itu?

It's like searching for a needle in trillions of haystacks.

Seperti halnya mencari jarum dalam tumpukan jerami.

We might want to focus our search on planets that we know can support life as we know it --

Kita ingin memfokuskan pencarian pada planet yang mampu menunjang kehidupan,

what we call habitable worlds.

yang kita sebut dunia layak huni.

What do such planets look like?

Seperti apa planet layak huni itu?

To answer that question, we don't look out there.

Untuk menjawabnya, kita tidak melihat ke luar sana.

Sebaliknya, kita melihat kemari, ke Bumi.

Instead, we look at ourselves. At Earth.

Because this is the one planet in the universe that we know for certain is habitable.

Sebab, Bumi adalah planet di alam semesta yang pastinya layak huni.

When we look at Earth from space, we see a blue, watery world.

Saat memandang Bumi dari luar angkasa, kita melihat dunia biru dipenuhi air.

It's no coincidence that three quarters of the surface is covered by oceans.

Bukanlah kebetulan bahwa tiga perempat permukaan Bumi adalah lautan.

Because of its unique chemical and physical properties,

Karena ciri kimia dan wujud yang unik, air sangatlah penting bagi kehidupan.

water is absolutely essential for all life as we know it.

And so we get especially excited about other worlds on which water is abundant.

Maka, kita akan kegirangan jika menemukan dunia lain yang memiliki banyak air.

Fortunately, water is very common in the universe.

Untungnya, air mudah ditemukan di alam semesta.

But life needs water in the form of liquid, not ice, and not vapor,

Namun, kehidupan membutuhkan air dalam bentuk cair, bukan es maupun uap.

and that's a little bit less common.

Bentuk cair itu jarang sekali ditemui.

For a planet to have liquid water at its surface, three things are important.

Ada tiga hal penting supaya permukaan planet dapat menampung air.

First, the planet needs to be large enough that the force of gravity

Pertama, planet harus cukup besar

supaya gaya gravitasi menahan molekul air agar tidak melayang ke luar angkasa.

keeps the water molecules from flying off into space.

For example, Mars is smaller than Earth, and so has less gravity,

Contohnya, Mars lebih kecil dari Bumi sehingga gaya gravitasinya lebih rendah.

and that's one important reason that Mars has a very thin atmosphere,

Itulah mengapa atmosfer Mars sangat tipis dan tidak ada lautan di permukaannya.

and no oceans at its surface.

Second, the planet needs to have an atmosphere. Why?

Kedua, planet harus memiliki atmosfer.

Mengapa?

Karena tanpa atmosfer, planet dalam keadaan vakum

Because without an atmosphere, the planet is in a vacuum,

and liquid water isn't stable in a vacuum.

dan air cair tidak stabil dalam keadaan vakum.

For example, our moon has no atmosphere, and so if you spill some water on the moon,

Misalnya, Bulan tidak punya atmosfer.

Jika kau menumpahkan air di Bulan, airnya akan menguap atau membeku.

it will either boil away as vapor, or freeze solid to make ice.

Without the pressure of an atmosphere, liquid water can't survive.

Tanpa tekanan dari atmosfer, air cair tidak akan bertahan.

Third, the planet needs to be at the right distance from its star.

Ketiga, planet harus berada pada jarak yang tepat dari bintangnya.

Too close, and the surface temperature will exceed the boiling point of water,

Jika terlalu dekat, suhu permukaan akan melebihi titik didih air

and oceans will turn to vapor.

dan lautan akan menguap.

Jika terlalu jauh, suhu permukaan akan turun di bawah titik beku air,

Too far, and the surface temperature will fall below the freezing point of water,

causing the oceans to turn to ice.

menyebabkan lautan menjadi es.

Fire or ice. For life as we know it, neither will suffice.

Api atau es.

Bagi kehidupan yang kita kenal, tak satu pun memadai.

You can imagine that the perfect zone where water stays liquid looks kind of like a belt around a star.

Dapat kau bayangkan zona sempurna agar air tetap cair

menyerupai sabuk yang mengelilingi bintang.

Kita menyebutnya zona layak huni.

We call that belt the habitable zone.

So when we search for habitable worlds, we definitely want to look for planets in the habitable zones around their stars.

Saat kita mencari dunia layak huni,

kita harus menemukan planet di zona layak huni di sekitar bintangnya.

Wilayah itu menjadi pertaruhan terbaik untuk menemukan planet seperti Bumi.

Those regions are the best bets to find planets like Earth.

But while habitable zones are a pretty good place to begin the search for planets with life,

Meskipun zona layak huni adalah permulaan yang baik

dalam mencari planet untuk kehidupan, masih ada beberapa rintangan.

there are a couple of complications.

Pertama, planet belum tentu layak huni hanya karena berada di zona layak huni,

First, a planet isn't necessarily habitable just because it's in the habitable zone.

Consider the planet Venus in our solar system.

seperti Planet Venus di tata surya kita.

If you were an alien astronomer, you'd think Venus is a pretty good bet for life.

Jika kau astronom alien, mungkin kau kira Venus cocok untuk makhluk hidup.

It's the right size, it has an atmosphere, and it's in the habitable zone of our sun.

Ukurannya pas, memiliki atmosfer, dan berada di zona layak huni Matahari.

An alien astronomer might see it as Earth's twin.

Astronom alien akan menganggapnya sebagai kembaran Bumi.

Namun, Venus tidak dapat dihuni, setidaknya di permukaannya.

But Venus is not habitable, at least not at its surface.

Tidak untuk makhluk hidup karena terlalu panas.

Not by life as we know it. It's too hot.

Atmosfer Venus dipenuhi karbon dioksida, gas rumah kaca utama.

That's because Venus' atmosphere is full of carbon dioxide, an important greenhouse gas.

In fact, its atmosphere is almost entirely carbon dioxide,

Bahkan, hampir seluruh atmosfernya dipenuhi karbon dioksida,

yang hampir 100 kali lebih tebal daripada di Bumi.

and is almost 100 times thicker than our own.

Alhasil, suhu di Venus begitu panas hingga dapat melelehkan timah

As a result, the temperature on Venus is hot enough to melt lead,

and the planet is dry as a bone.

dan planet itu sangatlah kering.

So finding planets of the right size and distance from their stars is only a beginning.

Planet dengan ukuran dan jarak yang tepat dari bintangnya barulah permulaan.

We also want to know about the makeup of their atmospheres.

Kita juga perlu mengetahui susunan atmosfer planetnya.

Rintangan kedua muncul ketika kita melihat Planet Bumi lebih dalam lagi.

The second complication emerges when we look a little more deeply at planet Earth.

Dalam 30 tahun terakhir, kita menemukan mikroba

In the last 30 years, we've discovered microbes living in all sorts of extreme environments.

hidup di segala jenis lingkungan ekstrem.

Kita menemukannya di celah batu bermil-mil di tanah,

We find them in fissures of rock miles beneath our feet,

in boiling waters of the ocean floor,

di dasar laut yang mendidih, di air asam dari mata air panas,

in acidic waters of thermal springs,

and in cloud droplets miles above our heads.

dan titik-titik air bermil-mil di atas kepala kita.

These so-called extremophiles aren't rare.

Makhluk bernama ekstremofil ini tidaklah langka.

Some scientists estimate that the mass of microbes living deep underground

Beberapa ilmuwan memperkirakan

kebanyakan massa mikroba yang hidup jauh di bawah tanah

menyamai jumlah kebanyakan makhluk hidup di permukaan Bumi.

equals the mass of all the life at Earth's surface.

Mikroba bawah tanah ini tidak membutuhkan lautan atau cahaya matahari.

These subterranean microbes don't need oceans or sunshine.

These discoveries suggest that Earth-like planets may be only the tip of the astrobiological iceberg.

Penemuan ini menunjukkan planet yang menyerupai Bumi

mungkin ibarat setetes air di lautan astrobiologi.

Mungkin saja makhluk hidup bertahan di akuifer di bawah permukaan Mars.

It's possible that life might persist in aquifers beneath the surface of Mars.

Microbes may thrive on Jupiter's moon Europa,

Mikroba mungkin hidup di bulannya Jupiter, Europa,

where liquid water ocean probably lies beneath the icy crust.

di mana air lautan yang cair terletak di bawah kerak esnya.

Lautan lain di bawah permukaan bulan Saturnus, Enceladus,

Another ocean beneath the surface of Saturn's moon Enceladus is the source of geysers erupting into space.

adalah sumber geiser yang menyembur ke luar angkasa.

Mungkinkah geiser ini mengeluarkan mikroba?

Could these geysers be raining microbes?

Bisakah kita terbang ke sana untuk mencari tahu?

Could we fly through them to find out?

And what about life as we don't know it, using a liquid other than water?

Bagaimana kehidupan yang kita tak tahu, menggunakan cairan selain air?

Maybe we are the crazy creatures living in an unusual and extreme environment.

Mungkin kitalah makhluk ganjilnya yang hidup di lingkungan asing dan ekstrem.

Maybe the real habitable zone is so large

Mungkin zona layak huni sebenarnya sangatlah luas

that there are billions of needles in those trillions of haystacks.

sehingga justru ada miliaran jarum di tumpukan jerami itu.

Maybe in the big scheme of things, Earth is only one of many different kinds of habitable worlds.

Dalam gambaran besarnya,

mungkin Bumi hanyalah satu dari ragam jenis dunia layak huni.

Satu-satunya cara mengetahuinya adalah dengan menjelajah ke luar sana.

The only way to find out is to go out and explore.