Mars And Venus Size

[Lorrine Hatala]

ihave a beginner telescope of 50mm and want to see planets it is arefractor with f/12 ratio and two eyepieces of 5mm and 10mm and i want to see mars, Jupiter, Saturn and venus. my max zoom ix 120x and focal length is 600mm

Venus, Mars, Jupiter, and Saturn are visible with your eyes, so a telescope and magnification are not required to see them. Depending on the quality of the telescope, the magnification will show you some details.Venus - you will be able to see the phase.Mars - for several months every 26 months, you will be able to see some dark markings and a polar cap.Jupiter - you will see the cloud bands and 4 of its moons.Saturn - you will see its rings and moon Titan.

The 5 mm ocular is probably a bit too much for this scope. You can definitely try it, but the expectation here is that the image will be a bit too washed out. With 50 mm of aperture you can't really expect to push magnification much above 100x (twice the aperture in mm), and even at around 100x it would work only if it's a high performance instrument. But, like I said, try and see what happens.

Jupiter - you will definitely see the disk. Seeing the equatorial belts will be more challenging, but it should be doable; it may take a few attempts if it doesn't work on first try. Jupiter is low contrast and it's hard to see its features. Let the image float through the field of view, relax and just take it in; after a few minutes your brain adapts to the view and starts perceiving more details.

Mars will probably not show a lot of details in 50 mm of aperture. Anyway, this planet is only worth observing for a few weeks around each opposition, which happens once every two years (plus a few weeks). At best you will resolve Mars as a tiny brick-red disk, but I doubt you'll see terrain features. But go ahead and give it a try; when the Hellas Basin is full of fog, or frosted over, it's very bright, so in a small aperture it might be perceived as a white speck of light on one side of the disk.

It's important to focus the instrument well before using it. E.g. point it at the Moon and adjust the focus until the image is as sharp as possible. You can also focus on stars - adjust focus until the image of the star is as small as it gets. You can also adjust focus on whatever object you're currently observing.

CARTER EMMART (Director of Astrovisualization): --50. 50 years since the first Earth Day, a celebration of the Earth because of the pictures brought back from the explorers, the Apollo mission astronauts on their way to the moon took pictures of the Earth.

And I'm Dr. Carter Emmart. I'm Director of Astrovisualization for the American Museum of Natural History, and we're pleased to bring you a program tonight we had originally planned to do in the Hayden Planetarium. But we're going to be bringing it to you tonight on software called OpenSpace. It is NASA supported that we're developing at the museum and several academic partners. If you are interested in obtaining this free software, our team is in the chat and ready to take your questions about it.

It's a great honor tonight to have the presentation by Dr. Martha Gilmore from Wesleyan University, and Dr. Gilmore is one of the world's leading authorities in the planet Venus. And understanding Earth, we've come to find out in outer space explorations is to understand the Earth in context to other planets.

Dr. Gilmore was one of our scientific advisors for our new space show at the planetarium called "Worlds Beyond Earth." And so Dr. Gilmore got her PhD at Brown University working with Dr. Jim Head, who was one of the leading geologists in developing the exploration of the moon and teaching the astronauts geology. So with great pleasure, we're going to turn this over now to Dr. Gilmore.

MARTHA GILMORE (George I. Seney Professor of Geology, Wesleyan University): Thank you, Carter. It's so nice to be here, and Happy Earth Day, everyone. I'm sorry that I can't see your faces in person, but I'm so glad that you tuned in today just to take a spin around the solar system with me on this amazing software that the American Museum has supported.

But I thought we'd start our journey by talking about starting at home. So this is an image of the Earth as we see it now all the time, right? Or images from space of the Earth. And for me, I suspect perhaps you as well, this image is a little emotional. It produces several feelings for me.

One feeling is just the awe of how beautiful the Earth is, the colors, this oceans, the clouds, and with that, the feeling of familiarity that this is the planet that we call home, right? That warmth of feeling like this is where we live. This is our place in the universe. And the third feeling, I think-- I feel, at least-- is a little bit of fear in that when you see Earth from this perspective, you realize how fragile our planet is, how small it is amongst the background of space.

Despite all this, the Earth is special. I mean because of all this, the Earth is incredibly special because even though we live in a universe that has trillions of galaxies and in all of those galaxies are trillions of stars, and we know now that in all-- around all those stars are trillions of planets. At this moment, the only evidence of life in the universe is us, right here on Earth. So as we think about our place, the question we ask is, we know that we're not the-- we know now that we're not the only Earth-sized planet, but are we-- is there only one Earth?

To address that question, we are lucky enough to have sent spacecraft amongst the planets of our solar system and have explored several of our neighbors. So as we back out here, we're looking at the Earth with the moon in orbit around it. And we're going to back out to see the orbits of our two neighbors-- Venus, which is closest to us, and Mars, away from us. What we've learned from the study of these worlds-- there's the orbit of Venus, and here's Mars.

What we've learned from the studies of these worlds is that although we are unique in the solar system today, our nearest neighbors, Venus and Mars, were once like us in that they were worlds of volcanism, they were worlds with atmospheres, and they were worlds with water. So what we understand now is that the early solar system contained three habitable worlds, each with an ocean, at the same time that life evolved on Earth. Did life evolve on those worlds as well? What happened to make those-- what happened to those once-habitable worlds?

One of the ways that we address whether a world is habitable has to do with its size. Mars is half the size of Venus and Earth-- Earth and Venus. And size dictates the length of time over which a planet is geologically active. Volcanism is the mechanism by which water gets into the atmosphere of a planet, and we know that life requires an atmosphere. And so Earth-size planets that support life should be-- Earth-- sorry. Planets that support life we expect to be geologically active. And if we look in our own solar system, the planet that is closest in size to us is the planet that's also closest to us, which is Venus.

We would like to discover Earth-like planets and explore them around other solar systems-- in other solar systems, but we have the opportunity to touch an Earth-size planet in our own solar system. And so what I'd like to do is travel to the planet next door, which is Venus. And we're going to show you a visualization from the planetarium show "Worlds Beyond Earth."

So what you're seeing on your screen right now is a-- shows the inner solar system, with the asteroid belt on the exterior. And now we're going to fly into Venus, which is the brightest planet in the sky. Venus, like Earth, has a substantial atmosphere. And as we zoom in, you can see that the brightness of this atmosphere is what causes it to look so bright to our eye.

What's being overlaid here in red is a visualization-- the interaction of the solar wind with the atmosphere of Venus. And because Venus lacks a magnetic field, one of the things that happens is that the solar wind is able to pull material off the atmosphere of Venus, material like hydrogen and oxygen, and strip them into space. So Venus gives us an idea about how water is lost on other Earth-size worlds, particularly exoplanets that lie closer to their host star.

The atmosphere of Venus is very thick and mostly CO2, so to see through it, we had to visualize it using radar. And what you're seeing here is the path of the Magellan spacecraft that was in orbit in Venus in the early '90s and mapped the surface of the planet so that we could understand the history of this world.

So what we're going to do now is we're going to descend through the atmosphere of Venus, and we're going to look at some of the images of the surface materials that we can see from the radar images of Magellan. So we're going to switch now back to Venus. There we go.

And as we approach, I want to appreciate the fact that Venus has a very thick CO2, carbon-dioxide-rich atmosphere-- so about 100 times thicker than the atmosphere of the Earth that you feel right now. That carbon dioxide produces a huge greenhouse effect, raising the temperature of the surface to about 450 degrees Celsius, which is 840-something degrees Fahrenheit. It's really hot.

So much can be learned about the greenhouse effect and how atmospheres evolve from the study of Venus. The effect of increasing CO2, the importance of a magnetic field, the maintenance of oxygen and atmospheres and ozone all can be learned by studying the thick atmosphere of Venus.

So as we descend, we're going to visit some volcanoes. The surface of-- what you're seeing here underneath the atmosphere are radar images, where the color that you see correlates to roughness. So things that are bright are rough on the centimeter scale, and things that are smooth are-- things that are dark are smooth. Magellan mapped the whole of the Venus surface, and what we see is that almost everything that is on the surface is volcanic.

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