Under $25

Features 3x Magnification Carry Case Included Lanyard Description Be ready whenever adventure calls with the lightweight National Geographi...

On this episode of How Do You KNOW? Dr Daniel Barth will be discussing what all is involved in the Fine Tuning of Nature.  Because we tend to suspe...

Jupiter is well named after the King of the Gods in Greek mythology, it is the largest planet in both mass and size, and possesses the ...

Misconceptions about large numbers are some of the most persistent and troublesome bits of misinformation. Not just children, but a lar...

The idea that tides are linked to the Moon is an old one. Galileo was one of the first scientists to develop the idea of tides being...

The French mathematician and astronomer, Edouard Roche, is most famous for his work on celestial mechanics and his discovery of t...

We all know that the gravitational field of any moon causes tides on its home planet. The height of the tide for a moon also depends upon the natur...

In August of 2006 the International Astronomical Union famously downgraded Pluto, which was considered the 9th planet in our solar system, to be re...

If you study science long enough, you eventually discover that Galileo was right about the constantly changing nature of scientific knowledge. Y...

There is a misconception that ‘doing real astronomy’ is difficult and expensive, only highly trained and generously funded people can do it; ...

Humans have attempted to map the stars in the sky since antiquity.  The earliest Western catalog of stars was created by the Greek astronomer...

  Fact, Hypothesis, Theory There is a distinct hierarchy in science that distinguishes facts, hypotheses, and theories. We misunderstand and ...

Mars - The Dying Planet Astronomers have been exploring Mars with telescopes for four centuries, and the fascination of the red planet with its ...

Russian biologist A. P. Oparin and Scottish biologist J. B. S. Haldane both proposed an early reducing atmosphere on Earth consisting of hydr...

The Viking Experiments In the early 1960’s, long before humans had left low Earth orbit, NASA was planning a mission to Mars that would soft-...

Sketching Saturn: The Box and Rectangle Method The first discoveries the system of the rings and moons around Saturn predate photographic tec...

Saturn has 7 major moons and more than 70 known moonlets. For the amateur astronomer, detecting and identifying these major moons is a challe...

We normally think of galaxies as some of the largest, brightest structures in the universe – but that isn’t always true. It is star formation t...

Ultra-diffuse galaxies are generally quenched dwarf galaxies with no gas reservoirs, they are therefore unable to form new stars; as a result, ...

The universe has always been mysterious and strange to us, but in fact it may be stranger than we can ever fathom. In this episode of How Do You...

In the second part of Dr. Barth's discussion on dark matter, he touches on why did galaxies form, the missing matter problem, and the Great Attr...

In this episode, Dr. Barth discusses the the difference between persuading someone to accept your opinion in an argument and arguing from eviden...

The creation of Earth's Moon is an age old question. There are pre-Apollo mission theories, of which three of the most popular ones will be d...

It's estimated that we will colonize Mars by 2050. The challenges to make it happen are daunting.  Dr. Barth touches on some of the problems tha...

Ideal for any situation, a unisex heavy blend crewneck sweatshirt is pure comfort. These garments are made from polyester and cotton. This combinat...

Dr. Daniel Barth returns with the 33rd episode of 'How Do You KNOW?' to discuss the Three Ring Theory that explains the formation of our solar s...

Dr. Daniel Barth gives us an overview of and will answer your questions about the James Webb Space Telescope in this 34th Episode of How Do You ...

Features Projection Clock Radio Controlled Digital Time Display Clock with NIST WWVB Receiver 180 Degree Rotatable Projection Head Time  Project...

The Official Coffee Mug of the Explore Alliance! The Explore Alliance is a community of amateur astronomers who come together to share their passio...

Dr. Daniel Barth gives us an overview of and will answer your questions about Lagrange Points in this 35th Episode of How Do You KNOW? https://e...

Dr. Daniel Barth gives us an overview of and will answer your questions about what happens When Asteroids Strike in this 36th Episode of How Do ...

What happens when the sun releases energy to create prominences, flares, mass ejections, and tsunamis, and how can those events affect us on ...

Description Converts 60mm thread to 53mm thread Available for FL and ED OTAs. Specs Optical Path Length 4mm Weight 22g Warranty Vix...

Description Converts 53mm thread to 43mm thread Available for FL and ED OTAs. Specs Optical Path Length 3mm Weight 19g Warranty Vix...

Essential for Time-Lapse Photography Specs Connecting to the POLARIE U 2.5mm stereo mini plug Connecting to the camera Accessory remote t...

Essential for Time-Lapse Photography Specs Connecting to the POLARIE U 2.5mm stereo mini plug Connecting to the camera Multi-connector pl...

In order to unlock the mysteries of the corona, but also to protect a society that is increasingly dependent on technology from the threats of s...

Today, astronomers and researchers, both professional and amateur, have unprecedented access to online science data, allowing a greater unders...

The first positive detection of water ice on Mars was from the Phoenix Lander that scraped away some surface dust to reveal pristine ice belo...

Humans have been obsessed with the measurement of time perhaps as far back as 100,000 years ago. Dr. Barth guides us through evidence of meas...

Stromatolite fossils are a dominant record of life for most of Earth’s history prior to the appearance of complex, multicellular organisms. S...

In 2019, NASA announced that an international team had found sugars essential to life in meteorites. The discovery added to the growing list o...

Aside from Earth, Mars is the most studied ecosystem by scientists today. With the process of collecting data from rovers and orbiting satelli...

Signed by the Author for Delivery at the Arizona Dark Sky Star Party The autobiography of Mike Weasner describes his journey through the Universe t...

This is part one of a two-part program on the Hubble Constant and the controversy about different values for this keystone unit of measurement. In...

This is part two of a two-part program on the Hubble Constant and the controversy about different values for this keystone unit of measurement. In...

Planetary nebulae are some of the most beautiful and intriguing deep sky objects in the Milky Way. They reveal the expanding, glowing shells of th...

From its discovery in 1846 until Clyde Tombaugh's discovery of Pluto in 1930, Neptune was the farthest-known planet. Now with the controversial re...