Life, the Universe and Everything

 

I'll bet I'm not the only person who reads/writes this blog who waited with bated breath until the first official pictures from the James Webb telescope were finally released.

This has to be the most profound, most deeply significant photograph I have ever seen.

The James Webb telescope primarily uses infrared light to create its images. Unlike the wonderful Hubble telescope, which orbits the Earth, Webb is positioned about 1.5 million kilometres from Earth, orbiting the sun. It was placed there so that it moves in synchronicity with Earth. This NASA article gives more information about Webb’s orbit and why the mirror needs special shielding from heat sources. In a nutshell, it’s because infrared light is heat and we want the telescope to collect the faint light of distant stars, not the blast from our sun.

In the image the telescope is collecting radiation from objects in very deep space. The bright objects with the striations are stars within our own Milky Way galaxy. The rest of the light sources are galaxies. Some of them have been distorted into arcs, revealing the curvature of spacetime caused by the gravity of a cluster of galaxies in the image’s centre. Some of those galaxies are billions of light years away – and indeed, it’s important to remember that what we see is a glimpse of the past because it has taken so long for the light from these distant sources to reach the telescope. Some of the objects in that image may have ceased to exist thousands of years ago. If they still exist, they will no longer be in the same place.

I found myself wondering how many stars are in those galaxies.

Our own Milky Way contains somewhere between one hundred and four hundred BILLION stars. You might wonder why the estimate is so vague. One reason is because we’re IN the galaxy, so it’s hard to tell its size. It’s a bit like trying to tell how big a mansion is if you’ve never seen anything but the inside of one room.

As a NASA scientist explains…

“There isn’t a way to simply count the number of stars in the Milky Way individually – that’s where the estimates come in. To make an estimate, we have to calculate the mass of our galaxy, and then the percentage of that mass that is made up of stars.

Then we have to decide what the mass of an average star is so we can calculate the number of stars in the galaxy. This is not trivial either – you could say our Sun is an average sized star, which would give you one estimate for the number of stars in the galaxy. But our Sun may not really be typical – there are a lot of much lower-mass stars out there. Using a low-mass red dwarf as an average-mass star will give you a totally different answer for the total number of stars in our galaxy.” [source]

But let’s settle for one hundred billion. I don’t know about you, but that’s enough for me to feel that little old Earth is pretty insignificant on the galactic scale.

Let’s take it a bit further.

If there are one hundred galaxies in that image, that’s 100,000,000,000,000 stars (one hundred trillion). And there are literally thousands of galaxies in that image. And that’s just one tiny fragment of space, what the telescope could fit into the view finder. In fact, it covers a patch of sky approximately the size of a grain of sand held at arm’s length by someone on the ground. Consider that scale and all those grains of sand. The Universe is unimaginably huge.

Is their intelligent life out there? Who knows. But the building blocks of life on Earth, DNA and RNA, have been found in meteorites [1] which suggests those components are not uncommon. Surely, among the trillions and trillions of stars and the even more trillions of planets out there, another intelligent species developed some time?

Then again, if they had their own Xi or Putin, or perhaps an Emperor Palpatine, maybe they became extinct long, long ago in a galaxy far, far away.

If you ever wondered why I describe myself as a ‘space nut’ – this is why. I love this stuff.

Cheers,

Greta van der Rol

 

NASA OFFERS GOOD NEWS FROM OTHER PLANETS

Hubble telescope image courtesy NASA

Earth-bound biologists, ecologists and climatologists have had little good news to offer us lately. But astrophysicists with their eyes on the skies continue to make new, more wondrous discoveries in exoplanetary science, assuring us that our own little solar system is not alone in the galaxy.

The older-generation Kepler and Hubble telescopes, which gave us our first glimpses of planets circling distance stars, have begun to reach their limit of usefulness. Kepler went dark last October, after almost a decade of observation from Earth orbit; Hubble remains fully functional after five in-orbit repairs but will eventually be replaced by the James Webb Space Telescope due to be launched in 2021. 

NASA’s newest tool in the hunt for exoplanets is the Transiting Exoplanet Survey Satellite, or TESS, which launched last April and began observations in July, 2018. In its first four months of operation, TESS found eight confirmed new planets and 320 more as-yet unconfirmed possibilities, according to Xu Chelsea Huang of MIT.

Observations from TESS are stretching our understanding of planetary formation and what a “planet” can look like. Some of TESS’s discoveries include HD21749b, only 52 light years away, with the lowest temperature known for a planet orbiting so close to a bright, nearby star. 

“If we want to study atmospheres of cool planets, this is the one to start with,” Huang said. The planet has a thick atmosphere, but Huang’s use of the term “cool” is relative: the planet is likely too hot and gassy to support life. Its orbit takes 36 Earth days, the longest known orbital period for planets transiting within 100 light-years of bright stars.

Or take the denizens of the star system Pi Mensae. Pi Mensae c orbits its star every 6.27 days and has a density similar to water; Pi Mensae b has a mass ten times that of Jupiter that orbits the star every 5.7 years in a wildly swinging ellipse—sometimes as close as that of Earth, sometimes as far as that of Jupiter.

Huang describes another planet TESS found, LHS 3844b, as “likely a lava world.” It has a radius just 1.3 times Earth’s, but it swings around its planet every 11 hours, giving it a surface temperature of about 540° C.

All of which goes to show that the universe is stranger by far than anyone could have predicted. These are only the newest planets among the thousands that have been discovered over the last decade by scientists using NASA instruments. And that can only be good news.

Cheers, Donna

*Information for this post taken from “Less than a year after launch, TESS is already finding bizarre worlds,” by Lisa Grossman, Science News, January 8, 2019.