Lunar south pole

In the last few months, 2 separate space missions launched in attempt to land on the Moon's south pole. Roscosmos's Lunar 25 unfortunately crash landed on the Moon, leaving behind a ~10m wide crater! On the other hand, the Indian Space Research Organisation launched Chandrayaan-3, which successfully self-landed on the south pole late August.

The south pole is notoriously difficult to land on because it has so many craters, with ridges reaching depths of a few kilometres. Congrats to all involved in this super complicated mission! :)

Water cycles on early Mars

Rapin et al. have been studying images taken by the Curiosity rover on Mars, which has driven approximately 30km over 3940 sols (a sol represents a Martian day, which is about 24 hours and 40 minutes long – so similar to Earth's day!) One of Curiosity's main objectives is to determine whether Mars ever supported life. For life here on Earth as we know it, it requires liquid water to survive. Now this obviously might not be the case for other life forms out there, but it's reasonable to assume so for reasons I won't get into today.

We already know that there are huge ice deposits on Mars. However, due to the thin atmosphere and low pressures, as soon as this ice is exposed it almost instantly vaporises into gas. So, we don't think there's any liquid water on the surface of Mars today; but if we take a look at the geology of the rocks on Mars, it tells us that there might've been in the past!

Rapin et al. noticed some features in images taken by Curiosity in June 2021 which suggest repeat flooding of an imaged crater. The images in the paper show hexagonal crack patterns – these happen when the same region floods ~10+ times. This dehydration/rehydration cycle is essential for the conversion of chemical elements to life forming molecules (i.e., proteins into amino acids).

SN 1987A

James Webb Space Telescope (JWST) captured this incredible image of SN (Supernova) 1987A:

At the centre, material ejected from the supernova forms a keyhole shape. This centre is packed with clumpy gas and dust ejected by the supernova explosion. The dust is so dense that even near-infrared light that Webb detects can’t penetrate it, shaping the dark “hole” in the middle.

So beautiful, yet so chilling.

JWST deepens "crisis in cosmology"

A paper released in August by Riess et al. is making a lot of headlines. Note: this publication has not been peer reviewed, yet.

Firstly, what even is the "crisis in cosmology?" To put it simply, we have 2 leading methods for calculating the expansion rate of our universe, both giving us very different answers. This means that either there's an issue with our observations of nearby galaxies, or there's an issue with our model of the universe in relation to the cosmic microwave background (CMB). My post last month, "is the universe twice as old as initially thought?," is kind of related to this, so check it out if you'd like to learn more :)

The hope is that JWST can help us iron out this discrepancy. To calculate the expansion rate using galaxies/supernovae, you need both the distance to the galaxy/star and the recession speed (how quickly the galaxy/star is moving away from us). The way we measure distance in this context is by measuring the brightness of an object. However, if an object is really far away, it becomes harder to resolve, making it "biased-bright." This is basically just a way of saying that we're over-estimating the brightness of the galaxy/star due to the objects around it and our limited resolution. If we are over-estimating, the galaxy/star is actually closer to us than the brightness measurement suggests. JWST has a very high resolution, so we're now able to get rid of this issue in many cases.

Riess et al. found that while scatter is reduced in the distance-speed plot for JWST data, the slope stays pretty much the same as what old data indicated. This would mean that it's unlikely that the problem is with our observations, but rather with our current model of the CMB. 

Orion

And finally, I've left my fave for last! As you can see from the picture at the top of this post, JWST captured a breathtaking new image of the Orion Nebula, a large region of star formation that's one of the closest stellar nurseries to our Solar System floating just 1,344 light-years away from us. This, along with Orion's high stellar activity rates, means that it's one of the few nebulae visible to the naked eye from Earth. It can be seen as a faint, hazy patch in the constellation of Orion. This makes it a super popular target for stargazers, and its existence has been logged for centuries, even by ancient civilisations.

published: 11/10/23 by kaan evcimen